diff --git a/cartographer/pose_graph/constraint/acceleration_constraint_3d.cc b/cartographer/pose_graph/constraint/acceleration_constraint_3d.cc
deleted file mode 100644
index 87fbf6a..0000000
--- a/cartographer/pose_graph/constraint/acceleration_constraint_3d.cc
+++ /dev/null
@@ -1,80 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/acceleration_constraint_3d.h"
-
-#include "absl/memory/memory.h"
-#include "cartographer/common/utils.h"
-#include "cartographer/pose_graph/constraint/constraint_utils.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-AccelerationConstraint3D::AccelerationConstraint3D(
-    const ConstraintId& id, const proto::LossFunction& loss_function_proto,
-    const proto::Acceleration3D& proto)
-    : Constraint(id, loss_function_proto),
-      first_(proto.first()),
-      second_(proto.second()),
-      third_(proto.third()),
-      imu_(proto.imu_calibration()),
-      cost_(new AccelerationCost3D(proto.parameters())),
-      ceres_cost_(absl::make_unique<AutoDiffFunction>(cost_)) {}
-
-void AccelerationConstraint3D::AddToSolver(Nodes* nodes,
-                                           ceres::Problem* problem) const {
-  FIND_NODE_OR_RETURN(first_node, first_, nodes->pose_3d_nodes,
-                      "First node was not found in pose_3d_nodes.");
-  FIND_NODE_OR_RETURN(second_node, second_, nodes->pose_3d_nodes,
-                      "Second node was not found in pose_3d_nodes.");
-  FIND_NODE_OR_RETURN(third_node, third_, nodes->pose_3d_nodes,
-                      "Third node was not found in pose_3d_nodes.");
-  FIND_NODE_OR_RETURN(
-      imu_node, imu_, nodes->imu_calibration_nodes,
-      "IMU calibration node was not found in imu_calibration_nodes.");
-
-  if (first_node->constant() && second_node->constant() &&
-      third_node->constant() && imu_node->constant()) {
-    LOG(INFO) << "All nodes are constant, skipping the constraint.";
-    return;
-  }
-
-  AddPose3D(first_node, problem);
-  AddPose3D(second_node, problem);
-  AddPose3D(third_node, problem);
-  AddImuCalibration(imu_node, problem);
-  problem->AddResidualBlock(ceres_cost_.get(), ceres_loss(),
-                            second_node->mutable_rotation()->data(),
-                            second_node->mutable_translation()->data(),
-                            first_node->mutable_translation()->data(),
-                            third_node->mutable_translation()->data(),
-                            imu_node->mutable_gravity_constant(),
-                            imu_node->mutable_orientation()->data());
-}
-
-proto::CostFunction AccelerationConstraint3D::ToCostFunctionProto() const {
-  proto::CostFunction cost_function;
-  auto* acceleration_3d = cost_function.mutable_acceleration_3d();
-  *acceleration_3d->mutable_first() = first_.ToProto();
-  *acceleration_3d->mutable_second() = second_.ToProto();
-  *acceleration_3d->mutable_third() = third_.ToProto();
-  *acceleration_3d->mutable_imu_calibration() = imu_.ToProto();
-  *acceleration_3d->mutable_parameters() = cost_->ToProto();
-  return cost_function;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/acceleration_constraint_3d.h b/cartographer/pose_graph/constraint/acceleration_constraint_3d.h
deleted file mode 100644
index 0321a83..0000000
--- a/cartographer/pose_graph/constraint/acceleration_constraint_3d.h
+++ /dev/null
@@ -1,61 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_ACCELERATION_CONSTRAINT_3D_H_
-#define CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_ACCELERATION_CONSTRAINT_3D_H_
-
-#include "cartographer/pose_graph/constraint/constraint.h"
-#include "cartographer/pose_graph/constraint/cost_function/acceleration_cost_3d.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-class AccelerationConstraint3D : public Constraint {
- public:
-  AccelerationConstraint3D(const ConstraintId& id,
-                           const proto::LossFunction& loss_function_proto,
-                           const proto::Acceleration3D& proto);
-
-  void AddToSolver(Nodes* nodes, ceres::Problem* problem) const final;
-
- protected:
-  proto::CostFunction ToCostFunctionProto() const final;
-
- private:
-  // clang-format off
-  using AutoDiffFunction =
-      ceres::AutoDiffCostFunction<AccelerationCost3D,
-                                  3 /* residuals */,
-                                  4 /* rotation variables second pose*/,
-                                  3 /* position variables second pose*/,
-                                  3 /* position variables first pose */,
-                                  3 /* position variables second pose */,
-                                  1 /* gravity variable */,
-                                  4 /* imu orientation */>;
-  // clang-format on
-  NodeId first_;
-  NodeId second_;
-  NodeId third_;
-  NodeId imu_;
-  // The cost function is owned by the ceres cost function.
-  AccelerationCost3D* const cost_;
-  std::unique_ptr<AutoDiffFunction> ceres_cost_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_ACCELERATION_CONSTRAINT_3D_H_
diff --git a/cartographer/pose_graph/constraint/acceleration_constraint_3d_test.cc b/cartographer/pose_graph/constraint/acceleration_constraint_3d_test.cc
deleted file mode 100644
index 7378df4..0000000
--- a/cartographer/pose_graph/constraint/acceleration_constraint_3d_test.cc
+++ /dev/null
@@ -1,57 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/acceleration_constraint_3d.h"
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using testing::EqualsProto;
-using testing::ParseProto;
-
-constexpr char kConstraint[] = R"PROTO(
-  id: "hal_acceleration"
-  cost_function {
-    acceleration_3d {
-      first { object_id: "hal9000" timestamp: 100 }
-      second { object_id: "hal9000" timestamp: 200 }
-      third { object_id: "hal9000" timestamp: 300 }
-      imu_calibration { object_id: "hal_imu" }
-      parameters {
-        delta_velocity_imu_frame { x: 1 y: 1 z: 1 }
-        first_to_second_delta_time_seconds: 10.0
-        second_to_third_delta_time_seconds: 20.0
-        scaling_factor: 2.0
-      }
-    }
-  }
-  loss_function { quadratic_loss {} }
-)PROTO";
-
-TEST(AccelerationConstraint3DTest, SerializesCorrectly) {
-  const auto proto = ParseProto<proto::Constraint>(kConstraint);
-  AccelerationConstraint3D constraint(proto.id(), proto.loss_function(),
-                                      proto.cost_function().acceleration_3d());
-  const auto actual_proto = constraint.ToProto();
-  EXPECT_THAT(actual_proto, EqualsProto(kConstraint));
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/constraint.cc b/cartographer/pose_graph/constraint/constraint.cc
deleted file mode 100644
index b6dce5a..0000000
--- a/cartographer/pose_graph/constraint/constraint.cc
+++ /dev/null
@@ -1,32 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/constraint.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-// TODO(pifon): Add a test.
-proto::Constraint Constraint::ToProto() const {
-  proto::Constraint constraint;
-  constraint.set_id(constraint_id_);
-  *constraint.mutable_cost_function() = ToCostFunctionProto();
-  *constraint.mutable_loss_function() = loss_function_.ToProto();
-  return constraint;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/constraint.h b/cartographer/pose_graph/constraint/constraint.h
deleted file mode 100644
index 0fcda85..0000000
--- a/cartographer/pose_graph/constraint/constraint.h
+++ /dev/null
@@ -1,63 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_CONSTRAINT_H_
-#define CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_CONSTRAINT_H_
-
-#include "cartographer/pose_graph/constraint/loss_function/loss_function.h"
-#include "cartographer/pose_graph/node/nodes.h"
-#include "cartographer/pose_graph/proto/constraint.pb.h"
-#include "ceres/problem.h"
-
-#include <string>
-
-namespace cartographer {
-namespace pose_graph {
-
-using ConstraintId = std::string;
-
-class Constraint {
- public:
-  Constraint(const ConstraintId& id,
-             const proto::LossFunction& loss_function_proto)
-      : constraint_id_(id), loss_function_(loss_function_proto) {}
-  virtual ~Constraint() = default;
-
-  Constraint(const Constraint&) = delete;
-  Constraint& operator=(const Constraint&) = delete;
-
-  proto::Constraint ToProto() const;
-
-  const ConstraintId& constraint_id() const { return constraint_id_; }
-
-  virtual void AddToSolver(Nodes* nodes, ceres::Problem* problem) const = 0;
-
- protected:
-  virtual proto::CostFunction ToCostFunctionProto() const = 0;
-
-  ceres::LossFunction* ceres_loss() const {
-    return loss_function_.ceres_loss();
-  }
-
- private:
-  ConstraintId constraint_id_;
-  LossFunction loss_function_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_CONSTRAINT_H_
diff --git a/cartographer/pose_graph/constraint/constraint_utils.cc b/cartographer/pose_graph/constraint/constraint_utils.cc
deleted file mode 100644
index 89e5dff..0000000
--- a/cartographer/pose_graph/constraint/constraint_utils.cc
+++ /dev/null
@@ -1,59 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/constraint_utils.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-void AddPose2D(Pose2D* pose, ceres::Problem* problem) {
-  auto pose_2d = pose->mutable_pose_2d();
-  problem->AddParameterBlock(pose_2d->data(), pose_2d->size());
-  if (pose->constant()) {
-    problem->SetParameterBlockConstant(pose_2d->data());
-  }
-}
-
-void AddPose3D(Pose3D* pose, ceres::Problem* problem) {
-  auto transation = pose->mutable_translation();
-  auto rotation = pose->mutable_rotation();
-
-  problem->AddParameterBlock(transation->data(), transation->size(),
-                             pose->translation_parameterization());
-  problem->AddParameterBlock(rotation->data(), rotation->size(),
-                             pose->rotation_parameterization());
-  if (pose->constant()) {
-    problem->SetParameterBlockConstant(transation->data());
-    problem->SetParameterBlockConstant(rotation->data());
-  }
-}
-
-void AddImuCalibration(ImuCalibration* imu_calibration,
-                       ceres::Problem* problem) {
-  auto gravity = imu_calibration->mutable_gravity_constant();
-  auto orientation = imu_calibration->mutable_orientation();
-
-  problem->AddParameterBlock(gravity, 1);
-  problem->AddParameterBlock(orientation->data(), orientation->size(),
-                             imu_calibration->orientation_parameterization());
-  if (imu_calibration->constant()) {
-    problem->SetParameterBlockConstant(gravity);
-    problem->SetParameterBlockConstant(orientation->data());
-  }
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/constraint_utils.h b/cartographer/pose_graph/constraint/constraint_utils.h
deleted file mode 100644
index 67cbaed..0000000
--- a/cartographer/pose_graph/constraint/constraint_utils.h
+++ /dev/null
@@ -1,53 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_CONSTRAINT_UTILS_H_
-#define CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_CONSTRAINT_UTILS_H_
-
-#include "cartographer/common/utils.h"
-#include "cartographer/pose_graph/node/imu_calibration.h"
-#include "cartographer/pose_graph/node/pose_2d.h"
-#include "cartographer/pose_graph/node/pose_3d.h"
-#include "ceres/problem.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-void AddPose2D(Pose2D* pose, ceres::Problem* problem);
-
-void AddPose3D(Pose3D* pose, ceres::Problem* problem);
-
-void AddImuCalibration(ImuCalibration* pose, ceres::Problem* problem);
-
-template <typename MapType,
-          typename UniquePtrType = typename MapType::mapped_type,
-          typename ValueTyper = typename UniquePtrType::element_type>
-ValueTyper* FindNodeOrNull(MapType& map, const NodeId& node_id) {
-  auto node = common::FindOrNull(map, node_id);
-  return node == nullptr ? nullptr : node->get();
-}
-
-#define FIND_NODE_OR_RETURN(node_name, node_id, map, log_message) \
-  auto node_name = FindNodeOrNull(map, node_id);                  \
-  if (node_name == nullptr) {                                     \
-    LOG(INFO) << log_message;                                     \
-    return;                                                       \
-  }
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_CONSTRAINT_UTILS_H_
diff --git a/cartographer/pose_graph/constraint/cost_function/acceleration_cost_3d.cc b/cartographer/pose_graph/constraint/cost_function/acceleration_cost_3d.cc
deleted file mode 100644
index 4ac374a..0000000
--- a/cartographer/pose_graph/constraint/cost_function/acceleration_cost_3d.cc
+++ /dev/null
@@ -1,47 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/cost_function/acceleration_cost_3d.h"
-
-#include "cartographer/transform/transform.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-AccelerationCost3D::AccelerationCost3D(
-    const proto::Acceleration3D::Parameters& parameters)
-    : delta_velocity_imu_frame_(
-          transform::ToEigen(parameters.delta_velocity_imu_frame())),
-      first_to_second_delta_time_seconds_(
-          parameters.first_to_second_delta_time_seconds()),
-      second_to_third_delta_time_seconds_(
-          parameters.second_to_third_delta_time_seconds()),
-      scaling_factor_(parameters.scaling_factor()) {}
-
-proto::Acceleration3D::Parameters AccelerationCost3D::ToProto() const {
-  proto::Acceleration3D::Parameters parameters;
-  *parameters.mutable_delta_velocity_imu_frame() =
-      transform::ToProto(delta_velocity_imu_frame_);
-  parameters.set_first_to_second_delta_time_seconds(
-      first_to_second_delta_time_seconds_);
-  parameters.set_second_to_third_delta_time_seconds(
-      second_to_third_delta_time_seconds_);
-  parameters.set_scaling_factor(scaling_factor_);
-  return parameters;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/cost_function/acceleration_cost_3d.h b/cartographer/pose_graph/constraint/cost_function/acceleration_cost_3d.h
deleted file mode 100644
index e93dc98..0000000
--- a/cartographer/pose_graph/constraint/cost_function/acceleration_cost_3d.h
+++ /dev/null
@@ -1,75 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_ACCELERATION_COST_3D_H_
-#define CARTOGRAPHER_ACCELERATION_COST_3D_H_
-
-#include "Eigen/Core"
-#include "Eigen/Geometry"
-#include "cartographer/pose_graph/proto/cost_function.pb.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-// Penalizes differences between IMU data and optimized accelerations.
-class AccelerationCost3D {
- public:
-  explicit AccelerationCost3D(
-      const proto::Acceleration3D::Parameters& parameters);
-
-  proto::Acceleration3D::Parameters ToProto() const;
-
-  template <typename T>
-  bool operator()(const T* const middle_rotation, const T* const start_position,
-                  const T* const middle_position, const T* const end_position,
-                  const T* const gravity_constant,
-                  const T* const imu_calibration, T* residual) const {
-    using Vector3T = Eigen::Matrix<T, 3, 1>;
-    using TranslationMap = Eigen::Map<const Vector3T>;
-    using RotationMap = Eigen::Map<const Eigen::Quaternion<T>>;
-
-    const Vector3T imu_delta_velocity =
-        RotationMap(middle_rotation) * RotationMap(imu_calibration) *
-            delta_velocity_imu_frame_.cast<T>() -
-        (*gravity_constant * 0.5 *
-         (first_to_second_delta_time_seconds_ +
-          second_to_third_delta_time_seconds_)) *
-            Eigen::Vector3d::UnitZ().cast<T>();
-
-    const Vector3T start_velocity =
-        (TranslationMap(middle_position) - TranslationMap(start_position)) /
-        T(first_to_second_delta_time_seconds_);
-    const Vector3T end_velocity =
-        (TranslationMap(end_position) - TranslationMap(middle_position)) /
-        T(second_to_third_delta_time_seconds_);
-    const Vector3T delta_velocity = end_velocity - start_velocity;
-
-    (Eigen::Map<Vector3T>(residual) =
-         T(scaling_factor_) * (imu_delta_velocity - delta_velocity));
-    return true;
-  }
-
- private:
-  const Eigen::Vector3d delta_velocity_imu_frame_;
-  const double first_to_second_delta_time_seconds_;
-  const double second_to_third_delta_time_seconds_;
-  const double scaling_factor_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_ACCELERATION_COST_3D_H_
diff --git a/cartographer/pose_graph/constraint/cost_function/acceleration_cost_3d_test.cc b/cartographer/pose_graph/constraint/cost_function/acceleration_cost_3d_test.cc
deleted file mode 100644
index fcb4645..0000000
--- a/cartographer/pose_graph/constraint/cost_function/acceleration_cost_3d_test.cc
+++ /dev/null
@@ -1,73 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/cost_function/acceleration_cost_3d.h"
-
-#include <array>
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using ::google::protobuf::TextFormat;
-using ::testing::ElementsAre;
-using testing::EqualsProto;
-using testing::Near;
-using testing::ParseProto;
-
-using PositionType = std::array<double, 3>;
-using RotationType = std::array<double, 4>;
-using ResidualType = std::array<double, 3>;
-
-constexpr char kParameters[] = R"PROTO(
-  delta_velocity_imu_frame { x: 1 y: 1 z: 1 }
-  first_to_second_delta_time_seconds: 10.0
-  second_to_third_delta_time_seconds: 20.0
-  scaling_factor: 2.0
-)PROTO";
-
-TEST(AccelerationCost3DTest, SerializesCorrectly) {
-  AccelerationCost3D acceleration_cost_3d(
-      ParseProto<proto::Acceleration3D::Parameters>(kParameters));
-  EXPECT_THAT(acceleration_cost_3d.ToProto(), EqualsProto(kParameters));
-}
-
-TEST(AccelerationCost3DTest, EvaluatesCorrectly) {
-  AccelerationCost3D acceleration_cost_3d(
-      ParseProto<proto::Acceleration3D::Parameters>(kParameters));
-  const PositionType kStartPosition{{1., 1., 1.}};
-
-  const PositionType kMiddlePosition{{2., 2., 2.}};
-  const RotationType kMiddleRotation{{0., 0., 0., 1.}};
-
-  const PositionType kEndPosition{{3., 3., 3.}};
-
-  const double kGravityConstant{10.};
-  const RotationType kImuCalibration{{0., 0., 0., 1.0}};
-
-  ResidualType residuals;
-  EXPECT_TRUE(acceleration_cost_3d(
-      kMiddleRotation.data(), kStartPosition.data(), kMiddlePosition.data(),
-      kEndPosition.data(), &kGravityConstant, kImuCalibration.data(),
-      residuals.data()));
-  EXPECT_THAT(residuals, ElementsAre(Near(2.1), Near(2.1), Near(-297.9)));
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_2d.cc b/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_2d.cc
deleted file mode 100644
index b09c74e..0000000
--- a/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_2d.cc
+++ /dev/null
@@ -1,48 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_2d.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-InterpolatedRelativePoseCost2D::InterpolatedRelativePoseCost2D(
-    const proto::InterpolatedRelativePose2D::Parameters& parameters)
-    : translation_weight_(parameters.translation_weight()),
-      rotation_weight_(parameters.rotation_weight()),
-      interpolation_factor_(parameters.interpolation_factor()),
-      first_T_second_(transform::ToRigid3(parameters.first_t_second())),
-      gravity_alignment_first_start_(
-          transform::ToEigen(parameters.gravity_alignment_first_start())),
-      gravity_alignment_first_end_(
-          transform::ToEigen(parameters.gravity_alignment_first_end())) {}
-
-proto::InterpolatedRelativePose2D::Parameters
-InterpolatedRelativePoseCost2D::ToProto() const {
-  proto::InterpolatedRelativePose2D::Parameters parameters;
-  parameters.set_translation_weight(translation_weight_);
-  parameters.set_rotation_weight(rotation_weight_);
-  parameters.set_interpolation_factor(interpolation_factor_);
-  *parameters.mutable_first_t_second() = transform::ToProto(first_T_second_);
-  *parameters.mutable_gravity_alignment_first_start() =
-      transform::ToProto(gravity_alignment_first_start_);
-  *parameters.mutable_gravity_alignment_first_end() =
-      transform::ToProto(gravity_alignment_first_end_);
-  return parameters;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_2d.h b/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_2d.h
deleted file mode 100644
index e86dfb5..0000000
--- a/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_2d.h
+++ /dev/null
@@ -1,66 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_COST_FUNCTION_INTERPOLATED_RELATIVE_POSE_COST_2D_H
-#define CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_COST_FUNCTION_INTERPOLATED_RELATIVE_POSE_COST_2D_H
-
-#include "cartographer/mapping/internal/optimization/cost_functions/cost_helpers.h"
-#include "cartographer/pose_graph/proto/cost_function.pb.h"
-#include "cartographer/transform/transform.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-// Provides cost function for relative pose and de/serialization methods.
-class InterpolatedRelativePoseCost2D {
- public:
-  explicit InterpolatedRelativePoseCost2D(
-      const proto::InterpolatedRelativePose2D::Parameters& parameters);
-
-  proto::InterpolatedRelativePose2D::Parameters ToProto() const;
-
-  template <typename T>
-  bool operator()(const T* const first_start_pose,
-                  const T* const first_end_pose,
-                  const T* const second_translation,
-                  const T* const second_rotation, T* const e) const {
-    const std::tuple<std::array<T, 4>, std::array<T, 3>>
-        interpolated_first_pose = mapping::optimization::InterpolateNodes2D(
-            first_start_pose, gravity_alignment_first_start_, first_end_pose,
-            gravity_alignment_first_end_, interpolation_factor_);
-    const std::array<T, 6> error = mapping::optimization::ScaleError(
-        mapping::optimization::ComputeUnscaledError(
-            first_T_second_, std::get<0>(interpolated_first_pose).data(),
-            std::get<1>(interpolated_first_pose).data(), second_rotation,
-            second_translation),
-        translation_weight_, rotation_weight_);
-    std::copy(std::begin(error), std::end(error), e);
-    return true;
-  }
-
- private:
-  const double translation_weight_;
-  const double rotation_weight_;
-  const double interpolation_factor_;
-  const transform::Rigid3d first_T_second_;
-  const Eigen::Quaterniond gravity_alignment_first_start_;
-  const Eigen::Quaterniond gravity_alignment_first_end_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_COST_FUNCTION_INTERPOLATED_RELATIVE_POSE_COST_2D_H
diff --git a/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_2d_test.cc b/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_2d_test.cc
deleted file mode 100644
index 7464e10..0000000
--- a/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_2d_test.cc
+++ /dev/null
@@ -1,76 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_2d.h"
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using ::testing::ElementsAre;
-using testing::EqualsProto;
-using testing::Near;
-using testing::ParseProto;
-
-using Position2DType = std::array<double, 3>;
-using TranslationType = std::array<double, 3>;
-using RotationType = std::array<double, 4>;
-using ResidualType = std::array<double, 6>;
-
-constexpr char kParameters[] = R"PROTO(
-  first_t_second {
-    translation: { x: 1 y: 2 z: 3 }
-    rotation: { x: 0 y: 0.3 z: 0.1 w: 0.2 }
-  }
-  translation_weight: 1
-  rotation_weight: 2
-  gravity_alignment_first_start { x: 0.4 y: 0.1 z: 0.3 w: 0.2 }
-  gravity_alignment_first_end { x: 0.3 y: 0.4 z: 0.2 w: 0.1 }
-  interpolation_factor: 0.3
-)PROTO";
-
-TEST(InterpolatedRelativePoseCost2DTest, SerializesCorrectly) {
-  const auto parameters =
-      ParseProto<proto::InterpolatedRelativePose2D::Parameters>(kParameters);
-  InterpolatedRelativePoseCost2D interpolated_relative_pose_cost_2d(parameters);
-  const auto actual_proto = interpolated_relative_pose_cost_2d.ToProto();
-  EXPECT_THAT(actual_proto, EqualsProto(kParameters));
-}
-
-TEST(InterpolatedRelativePoseCost2DTest, EvaluatesCorrectly) {
-  const auto parameters =
-      ParseProto<proto::InterpolatedRelativePose2D::Parameters>(kParameters);
-  InterpolatedRelativePoseCost2D interpolated_relative_pose_cost_2d(parameters);
-
-  const Position2DType kFirstStartPose{{1., 1., 1.}};
-  const Position2DType kFirstEndPose{{2., 3., 4.}};
-  const TranslationType kSecondTranslation{{0., -1., -2.}};
-  const RotationType kSecondRotation{{.4, .2, .3, .1}};
-
-  ResidualType residuals;
-  EXPECT_TRUE(interpolated_relative_pose_cost_2d(
-      kFirstStartPose.data(), kFirstEndPose.data(), kSecondTranslation.data(),
-      kSecondRotation.data(), residuals.data()));
-  EXPECT_THAT(residuals,
-              ElementsAre(Near(4.49044), Near(1.8527), Near(3.49511),
-                          Near(-1.93746), Near(3.54854), Near(4.50243)));
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_3d.cc b/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_3d.cc
deleted file mode 100644
index 5e30035..0000000
--- a/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_3d.cc
+++ /dev/null
@@ -1,40 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_3d.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-InterpolatedRelativePoseCost3D::InterpolatedRelativePoseCost3D(
-    const proto::InterpolatedRelativePose3D::Parameters& parameters)
-    : translation_weight_(parameters.translation_weight()),
-      rotation_weight_(parameters.rotation_weight()),
-      interpolation_factor_(parameters.interpolation_factor()),
-      first_T_second_(transform::ToRigid3(parameters.first_t_second())) {}
-
-proto::InterpolatedRelativePose3D::Parameters
-InterpolatedRelativePoseCost3D::ToProto() const {
-  proto::InterpolatedRelativePose3D::Parameters parameters;
-  parameters.set_translation_weight(translation_weight_);
-  parameters.set_rotation_weight(rotation_weight_);
-  parameters.set_interpolation_factor(interpolation_factor_);
-  *parameters.mutable_first_t_second() = transform::ToProto(first_T_second_);
-  return parameters;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
\ No newline at end of file
diff --git a/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_3d.h b/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_3d.h
deleted file mode 100644
index dab6c9c..0000000
--- a/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_3d.h
+++ /dev/null
@@ -1,71 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_COST_FUNCTION_INTERPOLATED_RELATIVE_POSE_COST_3D_H_
-#define CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_COST_FUNCTION_INTERPOLATED_RELATIVE_POSE_COST_3D_H_
-
-#include "cartographer/mapping/internal/optimization/cost_functions/cost_helpers.h"
-#include "cartographer/pose_graph/proto/cost_function.pb.h"
-#include "cartographer/transform/transform.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-// Provides cost function for interpolated relative pose in 3d and
-// de/serialization methods; only the first pose is linearly interpolated
-// between two nodes.
-class InterpolatedRelativePoseCost3D {
- public:
-  InterpolatedRelativePoseCost3D(
-      const proto::InterpolatedRelativePose3D::Parameters& parameters);
-
-  proto::InterpolatedRelativePose3D::Parameters ToProto() const;
-
-  template <typename T>
-  bool operator()(const T* const first_start_translation,
-                  const T* const first_start_rotation,
-                  const T* const first_end_translation,
-                  const T* const first_end_rotation,
-                  const T* const second_translation,
-                  const T* const second_rotation, T* const error_out) const {
-    const std::tuple<std::array<T, 4>, std::array<T, 3>>
-        interpolated_rotation_and_translation =
-            mapping::optimization::InterpolateNodes3D(
-                first_start_rotation, first_start_translation,
-                first_end_rotation, first_end_translation,
-                interpolation_factor_);
-    const std::array<T, 6> error = mapping::optimization::ScaleError(
-        mapping::optimization::ComputeUnscaledError(
-            first_T_second_,
-            std::get<0>(interpolated_rotation_and_translation).data(),
-            std::get<1>(interpolated_rotation_and_translation).data(),
-            second_rotation, second_translation),
-        translation_weight_, rotation_weight_);
-    std::copy(std::begin(error), std::end(error), error_out);
-    return true;
-  }
-
- private:
-  const double translation_weight_;
-  const double rotation_weight_;
-  const double interpolation_factor_;
-  const transform::Rigid3d first_T_second_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_COST_FUNCTION_INTERPOLATED_RELATIVE_POSE_COST_3D_H_
diff --git a/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_3d_test.cc b/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_3d_test.cc
deleted file mode 100644
index f5e88a0..0000000
--- a/cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_3d_test.cc
+++ /dev/null
@@ -1,76 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_3d.h"
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using ::testing::ElementsAre;
-using testing::EqualsProto;
-using testing::Near;
-using testing::ParseProto;
-
-using PositionType = std::array<double, 3>;
-using RotationType = std::array<double, 4>;
-using ResidualType = std::array<double, 6>;
-
-constexpr char kParameters[] = R"PROTO(
-  first_t_second {
-    translation: { x: 1 y: 2 z: 3 }
-    rotation: { x: 0 y: 0.3 z: 0.1 w: 0.2 }
-  }
-  translation_weight: 1
-  rotation_weight: 10
-  interpolation_factor: 0.3
-)PROTO";
-
-TEST(InterpolatedRelativePoseCost3DTest, SerializesCorrectly) {
-  const auto parameters =
-      ParseProto<proto::InterpolatedRelativePose3D::Parameters>(kParameters);
-  InterpolatedRelativePoseCost3D interpolated_relative_pose_cost_3d(parameters);
-  const auto actual_proto = interpolated_relative_pose_cost_3d.ToProto();
-  EXPECT_THAT(actual_proto, EqualsProto(kParameters));
-}
-
-TEST(InterpolatedRelativePoseCost3DTest, EvaluatesCorrectly) {
-  const auto parameters =
-      ParseProto<proto::InterpolatedRelativePose3D::Parameters>(kParameters);
-  InterpolatedRelativePoseCost3D interpolated_relative_pose_cost_3d(parameters);
-
-  const PositionType kFirstStartPosition{{1., 1., 1.}};
-  const RotationType kFirstStartRotation{{1., 1., 1., 1.}};
-  const PositionType kFirstEndPosition{{2., 3., 4.}};
-  const RotationType kFirstEndRotation{{1.1, 1.2, 1.3, 1.4}};
-  const PositionType kSecondPosition{{0., -1., -2.}};
-  const RotationType kSecondRotation{{.1, .2, .3, .4}};
-
-  ResidualType residuals;
-  EXPECT_TRUE(interpolated_relative_pose_cost_3d(
-      kFirstStartPosition.data(), kFirstStartRotation.data(),
-      kFirstEndPosition.data(), kFirstEndRotation.data(),
-      kSecondPosition.data(), kSecondRotation.data(), residuals.data()));
-  EXPECT_THAT(residuals,
-              ElementsAre(Near(8.4594), Near(10.27735), Near(-4.45472),
-                          Near(0.968852), Near(11.96531), Near(3.34254)));
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_2d.cc b/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_2d.cc
deleted file mode 100644
index fae18cc..0000000
--- a/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_2d.cc
+++ /dev/null
@@ -1,94 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/cost_function/relative_pose_cost_2d.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-RelativePoseCost2D::RelativePoseCost2D(
-    const proto::RelativePose2D::Parameters& parameters)
-    : translation_weight_(parameters.translation_weight()),
-      rotation_weight_(parameters.rotation_weight()),
-      first_T_second_(transform::ToRigid2(parameters.first_t_second())) {}
-
-proto::RelativePose2D::Parameters RelativePoseCost2D::ToProto() const {
-  proto::RelativePose2D::Parameters parameters;
-  parameters.set_translation_weight(translation_weight_);
-  parameters.set_rotation_weight(rotation_weight_);
-  *parameters.mutable_first_t_second() = transform::ToProto(first_T_second_);
-  return parameters;
-}
-
-bool RelativePoseCost2D::Evaluate(double const* const* parameters,
-                                  double* residuals, double** jacobians) const {
-  double const* start = parameters[0];
-  double const* end = parameters[1];
-
-  const double cos_start_rotation = cos(start[2]);
-  const double sin_start_rotation = sin(start[2]);
-  const double delta_x = end[0] - start[0];
-  const double delta_y = end[1] - start[1];
-
-  residuals[0] =
-      translation_weight_ *
-      (first_T_second_.translation().x() -
-       (cos_start_rotation * delta_x + sin_start_rotation * delta_y));
-  residuals[1] =
-      translation_weight_ *
-      (first_T_second_.translation().y() -
-       (-sin_start_rotation * delta_x + cos_start_rotation * delta_y));
-  residuals[2] = rotation_weight_ *
-                 common::NormalizeAngleDifference(
-                     first_T_second_.rotation().angle() - (end[2] - start[2]));
-  if (jacobians == nullptr) return true;
-
-  const double weighted_cos_start_rotation =
-      translation_weight_ * cos_start_rotation;
-  const double weighted_sin_start_rotation =
-      translation_weight_ * sin_start_rotation;
-
-  // Jacobians in Ceres are ordered by the parameter blocks:
-  // jacobian[i] = [(dr_0 / dx_i)^T, ..., (dr_n / dx_i)^T].
-  if (jacobians[0] != nullptr) {
-    jacobians[0][0] = weighted_cos_start_rotation;
-    jacobians[0][1] = weighted_sin_start_rotation;
-    jacobians[0][2] = weighted_sin_start_rotation * delta_x -
-                      weighted_cos_start_rotation * delta_y;
-    jacobians[0][3] = -weighted_sin_start_rotation;
-    jacobians[0][4] = weighted_cos_start_rotation;
-    jacobians[0][5] = weighted_cos_start_rotation * delta_x +
-                      weighted_sin_start_rotation * delta_y;
-    jacobians[0][6] = 0;
-    jacobians[0][7] = 0;
-    jacobians[0][8] = rotation_weight_;
-  }
-  if (jacobians[1] != nullptr) {
-    jacobians[1][0] = -weighted_cos_start_rotation;
-    jacobians[1][1] = -weighted_sin_start_rotation;
-    jacobians[1][2] = 0;
-    jacobians[1][3] = weighted_sin_start_rotation;
-    jacobians[1][4] = -weighted_cos_start_rotation;
-    jacobians[1][5] = 0;
-    jacobians[1][6] = 0;
-    jacobians[1][7] = 0;
-    jacobians[1][8] = -rotation_weight_;
-  }
-  return true;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_2d.h b/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_2d.h
deleted file mode 100644
index 5395e89..0000000
--- a/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_2d.h
+++ /dev/null
@@ -1,51 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_COST_FUNCTION_RELATIVE_POSE_COST_2D_H_
-#define CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_COST_FUNCTION_RELATIVE_POSE_COST_2D_H_
-
-#include "cartographer/pose_graph/proto/cost_function.pb.h"
-#include "cartographer/transform/transform.h"
-#include "ceres/sized_cost_function.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-class RelativePoseCost2D
-    : public ceres::SizedCostFunction<3 /* number of residuals */,
-                                      3 /* size of first pose */,
-                                      3 /* size of second pose */> {
- public:
-  explicit RelativePoseCost2D(
-      const proto::RelativePose2D::Parameters& parameters);
-
-  proto::RelativePose2D::Parameters ToProto() const;
-
-  // Parameters are packed as [first_pose_2d, second_pose_2d], where each 2D
-  // pose is [translation_x, translation_y, rotation].
-  bool Evaluate(double const* const* parameters, double* residuals,
-                double** jacobians) const final;
-
- private:
-  const double translation_weight_;
-  const double rotation_weight_;
-  const transform::Rigid2d first_T_second_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_COST_FUNCTION_RELATIVE_POSE_COST_2D_H_
diff --git a/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_2d_test.cc b/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_2d_test.cc
deleted file mode 100644
index cf1a23f..0000000
--- a/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_2d_test.cc
+++ /dev/null
@@ -1,117 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/cost_function/relative_pose_cost_2d.h"
-
-#include "absl/memory/memory.h"
-#include "cartographer/testing/test_helpers.h"
-#include "ceres/gradient_checker.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-constexpr int kPoseDimension = 3;
-constexpr int kResidualsCount = 3;
-constexpr int kParameterBlocksCount = 2;
-constexpr int kJacobianColDimension = kResidualsCount * kPoseDimension;
-
-using ::testing::ElementsAre;
-using testing::EqualsProto;
-using testing::Near;
-using testing::ParseProto;
-
-using ResidualType = std::array<double, kResidualsCount>;
-using JacobianType = std::array<std::array<double, kJacobianColDimension>,
-                                kParameterBlocksCount>;
-
-constexpr char kParameters[] = R"PROTO(
-  first_t_second {
-    translation: { x: 1 y: 1 }
-    rotation: -2.214297
-  }
-  translation_weight: 1
-  rotation_weight: 10
-)PROTO";
-
-class RelativePoseCost2DTest : public ::testing::Test {
- public:
-  RelativePoseCost2DTest()
-      : relative_pose_cost_2d_(absl::make_unique<RelativePoseCost2D>(
-            ParseProto<proto::RelativePose2D::Parameters>(kParameters))) {
-    for (int i = 0; i < kParameterBlocksCount; ++i) {
-      jacobian_ptrs_[i] = jacobian_[i].data();
-    }
-  }
-
-  std::pair<const ResidualType&, const JacobianType&>
-  EvaluateRelativePoseCost2D(
-      const std::array<const double*, 2>& parameter_blocks) {
-    relative_pose_cost_2d_->Evaluate(parameter_blocks.data(), residuals_.data(),
-                                     jacobian_ptrs_.data());
-    return std::make_pair(std::cref(residuals_), std::cref(jacobian_));
-  }
-
- protected:
-  ResidualType residuals_;
-  JacobianType jacobian_;
-  std::array<double*, kParameterBlocksCount> jacobian_ptrs_;
-  std::unique_ptr<RelativePoseCost2D> relative_pose_cost_2d_;
-};
-
-TEST_F(RelativePoseCost2DTest, SerializesCorrectly) {
-  EXPECT_THAT(relative_pose_cost_2d_->ToProto(), EqualsProto(kParameters));
-}
-
-TEST_F(RelativePoseCost2DTest, CheckGradient) {
-  std::array<double, kPoseDimension> start_pose{{1., 1., 1.}};
-  std::array<double, kPoseDimension> end_pose{{10., 1., 100.}};
-  std::array<const double*, kParameterBlocksCount> parameter_blocks{
-      {start_pose.data(), end_pose.data()}};
-
-  using ::ceres::GradientChecker;
-  GradientChecker gradient_checker(relative_pose_cost_2d_.get(),
-                                   {} /* local parameterizations */,
-                                   ceres::NumericDiffOptions{});
-
-  GradientChecker::ProbeResults probe_results;
-  gradient_checker.Probe(parameter_blocks.data(),
-                         1e-08 /* relative precision */, &probe_results);
-  EXPECT_TRUE(probe_results.return_value);
-}
-
-TEST_F(RelativePoseCost2DTest, EvaluateRelativePoseCost2D) {
-  std::array<double, kPoseDimension> start_pose{{1., 1., 1.}};
-  std::array<double, kPoseDimension> end_pose{{10., 1., 100.}};
-  std::array<const double*, kParameterBlocksCount> parameter_blocks{
-      {start_pose.data(), end_pose.data()}};
-
-  auto residuals_and_jacobian = EvaluateRelativePoseCost2D(parameter_blocks);
-  EXPECT_THAT(residuals_and_jacobian.first,
-              ElementsAre(Near(-3.86272), Near(8.57324), Near(-6.83333)));
-  EXPECT_THAT(
-      residuals_and_jacobian.second,
-      ElementsAre(
-          ElementsAre(Near(0.540302), Near(0.841471), Near(7.57324),
-                      Near(-0.841471), Near(0.540302), Near(4.86272), Near(0),
-                      Near(0), Near(10)),
-          ElementsAre(Near(-0.540302), Near(-0.841471), Near(0), Near(0.841471),
-                      Near(-0.540302), Near(0), Near(0), Near(0), Near(-10))));
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_3d.cc b/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_3d.cc
deleted file mode 100644
index 9293fd9..0000000
--- a/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_3d.cc
+++ /dev/null
@@ -1,37 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/cost_function/relative_pose_cost_3d.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-RelativePoseCost3D::RelativePoseCost3D(
-    const proto::RelativePose3D::Parameters& parameters)
-    : translation_weight_(parameters.translation_weight()),
-      rotation_weight_(parameters.rotation_weight()),
-      first_T_second_(transform::ToRigid3(parameters.first_t_second())) {}
-
-proto::RelativePose3D::Parameters RelativePoseCost3D::ToProto() const {
-  proto::RelativePose3D::Parameters parameters;
-  parameters.set_translation_weight(translation_weight_);
-  parameters.set_rotation_weight(rotation_weight_);
-  *parameters.mutable_first_t_second() = transform::ToProto(first_T_second_);
-  return parameters;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
\ No newline at end of file
diff --git a/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_3d.h b/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_3d.h
deleted file mode 100644
index 9c68a7e..0000000
--- a/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_3d.h
+++ /dev/null
@@ -1,57 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_RELATIVE_POSE_COST_3D_H
-#define CARTOGRAPHER_RELATIVE_POSE_COST_3D_H
-
-#include "cartographer/mapping/internal/optimization/cost_functions/cost_helpers.h"
-#include "cartographer/pose_graph/proto/cost_function.pb.h"
-#include "cartographer/transform/transform.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-// Provides cost function for relative pose and de/serialization methods.
-class RelativePoseCost3D {
- public:
-  explicit RelativePoseCost3D(
-      const proto::RelativePose3D::Parameters& parameters);
-
-  proto::RelativePose3D::Parameters ToProto() const;
-
-  template <typename T>
-  bool operator()(const T* const c_i_translation, const T* const c_i_rotation,
-                  const T* const c_j_translation, const T* const c_j_rotation,
-                  T* const error_out) const {
-    const std::array<T, 6> error = mapping::optimization::ScaleError(
-        mapping::optimization::ComputeUnscaledError(
-            first_T_second_, c_i_rotation, c_i_translation, c_j_rotation,
-            c_j_translation),
-        translation_weight_, rotation_weight_);
-    std::copy(std::begin(error), std::end(error), error_out);
-    return true;
-  }
-
- private:
-  const double translation_weight_;
-  const double rotation_weight_;
-  const transform::Rigid3d first_T_second_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_RELATIVE_POSE_COST_3D_H
diff --git a/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_3d_test.cc b/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_3d_test.cc
deleted file mode 100644
index d44ad61..0000000
--- a/cartographer/pose_graph/constraint/cost_function/relative_pose_cost_3d_test.cc
+++ /dev/null
@@ -1,76 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/cost_function/relative_pose_cost_3d.h"
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using ::testing::ElementsAre;
-using testing::EqualsProto;
-using testing::Near;
-using testing::ParseProto;
-
-using PositionType = std::array<double, 3>;
-using RotationType = std::array<double, 4>;
-using ResidualType = std::array<double, 6>;
-
-constexpr char kParameters[] = R"PROTO(
-  first_t_second {
-    translation: { x: 1 y: 2 z: 3 }
-    rotation: { x: 0 y: 0.3 z: 0.1 w: 0.2 }
-  }
-  translation_weight: 1
-  rotation_weight: 10
-)PROTO";
-
-TEST(RelativePoseCost3DTest, SerializesCorrectly) {
-  auto relative_pose_parameters =
-      ParseProto<proto::RelativePose3D::Parameters>(kParameters);
-  RelativePoseCost3D relative_pose_cost_3d(relative_pose_parameters);
-  const auto actual_proto = relative_pose_cost_3d.ToProto();
-  EXPECT_THAT(actual_proto, EqualsProto(kParameters));
-}
-
-TEST(RelativePoseCost3DTest, EvaluatesCorrectly) {
-  auto relative_pose_parameters =
-      ParseProto<proto::RelativePose3D::Parameters>(kParameters);
-  RelativePoseCost3D relative_pose_cost_3d(relative_pose_parameters);
-
-  const PositionType kPosition1{{1., 1., 1.}};
-  const RotationType kRotation1{{1., 1., 1., 1.}};
-  ResidualType residuals;
-  EXPECT_TRUE(relative_pose_cost_3d(kPosition1.data(), kRotation1.data(),
-                                    kPosition1.data(), kRotation1.data(),
-                                    residuals.data()));
-  EXPECT_THAT(residuals, ElementsAre(Near(1), Near(2), Near(3), Near(0),
-                                     Near(19.1037), Near(6.3679)));
-
-  const PositionType kPosition2{{0., -1., -2.}};
-  const RotationType kRotation2{{.1, .2, .3, .4}};
-  EXPECT_TRUE(relative_pose_cost_3d(kPosition1.data(), kRotation1.data(),
-                                    kPosition2.data(), kRotation2.data(),
-                                    residuals.data()));
-  EXPECT_THAT(residuals, ElementsAre(Near(6), Near(8), Near(-2), Near(1.03544),
-                                     Near(11.38984), Near(3.10632)));
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/cost_function/rotation_cost_3d.cc b/cartographer/pose_graph/constraint/cost_function/rotation_cost_3d.cc
deleted file mode 100644
index 24aa9d8..0000000
--- a/cartographer/pose_graph/constraint/cost_function/rotation_cost_3d.cc
+++ /dev/null
@@ -1,38 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/cost_function/rotation_cost_3d.h"
-
-#include "cartographer/transform/transform.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-RotationCost3D::RotationCost3D(const proto::Rotation3D::Parameters& parameters)
-    : scaling_factor_(parameters.scaling_factor()),
-      delta_rotation_imu_frame_(
-          transform::ToEigen(parameters.delta_rotation_imu_frame())) {}
-
-proto::Rotation3D::Parameters RotationCost3D::ToProto() const {
-  proto::Rotation3D::Parameters parameters;
-  parameters.set_scaling_factor(scaling_factor_);
-  *parameters.mutable_delta_rotation_imu_frame() =
-      transform::ToProto(delta_rotation_imu_frame_);
-  return parameters;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
\ No newline at end of file
diff --git a/cartographer/pose_graph/constraint/cost_function/rotation_cost_3d.h b/cartographer/pose_graph/constraint/cost_function/rotation_cost_3d.h
deleted file mode 100644
index 45842bc..0000000
--- a/cartographer/pose_graph/constraint/cost_function/rotation_cost_3d.h
+++ /dev/null
@@ -1,63 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_ROTATION_COST_3D_H
-#define CARTOGRAPHER_ROTATION_COST_3D_H
-
-#include "Eigen/Core"
-#include "Eigen/Geometry"
-#include "cartographer/pose_graph/proto/cost_function.pb.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-// Provides cost function for 3D rotation and de/serialization methods. The cost
-// function penalizes differences between IMU data and optimized orientations.
-class RotationCost3D {
- public:
-  explicit RotationCost3D(const proto::Rotation3D::Parameters& parameters);
-
-  proto::Rotation3D::Parameters ToProto() const;
-
-  // Cost function expecting three quaternions as input and 3D vector as output.
-  template <typename T>
-  bool operator()(const T* const start_rotation, const T* const end_rotation,
-                  const T* const imu_calibration, T* residual) const {
-    const Eigen::Quaternion<T> start(start_rotation[0], start_rotation[1],
-                                     start_rotation[2], start_rotation[3]);
-    const Eigen::Quaternion<T> end(end_rotation[0], end_rotation[1],
-                                   end_rotation[2], end_rotation[3]);
-    const Eigen::Quaternion<T> eigen_imu_calibration(
-        imu_calibration[0], imu_calibration[1], imu_calibration[2],
-        imu_calibration[3]);
-    const Eigen::Quaternion<T> error =
-        end.conjugate() * start * eigen_imu_calibration *
-        delta_rotation_imu_frame_.cast<T>() * eigen_imu_calibration.conjugate();
-    residual[0] = scaling_factor_ * error.x();
-    residual[1] = scaling_factor_ * error.y();
-    residual[2] = scaling_factor_ * error.z();
-    return true;
-  }
-
- private:
-  const double scaling_factor_;
-  const Eigen::Quaterniond delta_rotation_imu_frame_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_ROTATION_COST_3D_H
diff --git a/cartographer/pose_graph/constraint/cost_function/rotation_cost_3d_test.cc b/cartographer/pose_graph/constraint/cost_function/rotation_cost_3d_test.cc
deleted file mode 100644
index ca6d1ea..0000000
--- a/cartographer/pose_graph/constraint/cost_function/rotation_cost_3d_test.cc
+++ /dev/null
@@ -1,66 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/cost_function/rotation_cost_3d.h"
-
-#include <array>
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using ::testing::ElementsAre;
-using testing::EqualsProto;
-using testing::Near;
-using testing::ParseProto;
-
-using RotationType = std::array<double, 4>;
-using ResidualType = std::array<double, 3>;
-
-constexpr char kParameters[] = R"PROTO(
-  delta_rotation_imu_frame { x: 0 y: 0.1 z: 0.2 w: 0.3 }
-  scaling_factor: 0.4
-)PROTO";
-
-TEST(RotationCost3DTest, SerializesCorrectly) {
-  const auto parameters =
-      ParseProto<proto::Rotation3D::Parameters>(kParameters);
-  RotationCost3D rotation_cost_3d(parameters);
-  const auto actual_proto = rotation_cost_3d.ToProto();
-  EXPECT_THAT(actual_proto, EqualsProto(kParameters));
-}
-
-TEST(RotationCost3DTest, EvaluatesCorrectly) {
-  const auto parameters =
-      ParseProto<proto::Rotation3D::Parameters>(kParameters);
-  RotationCost3D rotation_cost_3d(parameters);
-
-  const RotationType kStartRotation{{1., 1., 1., 1.}};
-  const RotationType kEndRotation{{1.1, 1.2, 1.3, 1.4}};
-  const RotationType kImuCalibration{{0.1, 0.1, 0.1, 0.1}};
-  ResidualType residuals;
-  rotation_cost_3d(kStartRotation.data(), kEndRotation.data(),
-                   kImuCalibration.data(), residuals.data());
-
-  EXPECT_THAT(residuals,
-              ElementsAre(Near(0.01536), Near(-0.00256), Near(0.00832)));
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.cc b/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.cc
deleted file mode 100644
index 7e8154b..0000000
--- a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.cc
+++ /dev/null
@@ -1,75 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.h"
-
-#include "absl/memory/memory.h"
-#include "cartographer/common/utils.h"
-#include "cartographer/pose_graph/constraint/constraint_utils.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-InterpolatedRelativePoseConstraint2D::InterpolatedRelativePoseConstraint2D(
-    const ConstraintId& id, const proto::LossFunction& loss_function_proto,
-    const proto::InterpolatedRelativePose2D& proto)
-    : Constraint(id, loss_function_proto),
-      first_start_(proto.first_start()),
-      first_end_(proto.first_end()),
-      second_(proto.second()),
-      cost_(new InterpolatedRelativePoseCost2D(proto.parameters())),
-      ceres_cost_(absl::make_unique<AutoDiffFunction>(cost_)) {}
-
-void InterpolatedRelativePoseConstraint2D::AddToSolver(
-    Nodes* nodes, ceres::Problem* problem) const {
-  FIND_NODE_OR_RETURN(first_node_start, first_start_, nodes->pose_2d_nodes,
-                      "First node (start) was not found in pose_2d_nodes.");
-  FIND_NODE_OR_RETURN(first_node_end, first_end_, nodes->pose_2d_nodes,
-                      "First node (end) was not found in pose_2d_nodes.");
-  FIND_NODE_OR_RETURN(second_node, second_, nodes->pose_3d_nodes,
-                      "Second node was not found in pose_3d_nodes.");
-
-  if (first_node_start->constant() && first_node_end->constant() &&
-      second_node->constant()) {
-    LOG(INFO) << "All nodes are constant, skipping the constraint.";
-    return;
-  }
-
-  AddPose2D(first_node_start, problem);
-  AddPose2D(first_node_end, problem);
-  AddPose3D(second_node, problem);
-  problem->AddResidualBlock(ceres_cost_.get(), ceres_loss(),
-                            first_node_start->mutable_pose_2d()->data(),
-                            first_node_end->mutable_pose_2d()->data(),
-                            second_node->mutable_translation()->data(),
-                            second_node->mutable_rotation()->data());
-}
-
-proto::CostFunction InterpolatedRelativePoseConstraint2D::ToCostFunctionProto()
-    const {
-  proto::CostFunction cost_function;
-  auto* interpolated_relative_pose_2d =
-      cost_function.mutable_interpolated_relative_pose_2d();
-  *interpolated_relative_pose_2d->mutable_first_start() =
-      first_start_.ToProto();
-  *interpolated_relative_pose_2d->mutable_first_end() = first_end_.ToProto();
-  *interpolated_relative_pose_2d->mutable_second() = second_.ToProto();
-  *interpolated_relative_pose_2d->mutable_parameters() = cost_->ToProto();
-  return cost_function;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.h b/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.h
deleted file mode 100644
index 5635334..0000000
--- a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.h
+++ /dev/null
@@ -1,59 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_INTERPOLATED_RELATIVE_POSE_CONSTRAINT_2D_H_
-#define CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_INTERPOLATED_RELATIVE_POSE_CONSTRAINT_2D_H_
-
-#include "cartographer/pose_graph/constraint/constraint.h"
-#include "cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_2d.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-class InterpolatedRelativePoseConstraint2D : public Constraint {
- public:
-  InterpolatedRelativePoseConstraint2D(
-      const ConstraintId& id, const proto::LossFunction& loss_function_proto,
-      const proto::InterpolatedRelativePose2D& proto);
-
-  void AddToSolver(Nodes* nodes, ceres::Problem* problem) const final;
-
- protected:
-  proto::CostFunction ToCostFunctionProto() const final;
-
- private:
-  // clang-format off
-  using AutoDiffFunction = ceres::AutoDiffCostFunction<
-      InterpolatedRelativePoseCost2D,
-      6 /* residuals */,
-      3 /* 2d pose variables of first start pose */,
-      3 /* 2d pose variables of first end pose */,
-      3 /* translation of second pose */,
-      4 /* rotation of second pose */>;
-  // clang-format on
-  NodeId first_start_;
-  NodeId first_end_;
-  NodeId second_;
-
-  // The cost function is owned by the ceres cost function.
-  InterpolatedRelativePoseCost2D* const cost_;
-  std::unique_ptr<AutoDiffFunction> ceres_cost_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_INTERPOLATED_RELATIVE_POSE_CONSTRAINT_2D_H_
diff --git a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d_test.cc b/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d_test.cc
deleted file mode 100644
index 8659876..0000000
--- a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d_test.cc
+++ /dev/null
@@ -1,62 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.h"
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using testing::EqualsProto;
-using testing::ParseProto;
-
-constexpr char kConstraint[] = R"PROTO(
-  id: "narf"
-  cost_function {
-    interpolated_relative_pose_2d {
-      first_start { object_id: "node0_start" }
-      first_end { object_id: "node0_end" }
-      second { object_id: "node1" }
-      parameters {
-        first_t_second {
-          translation: { x: 1 y: 2 z: 3 }
-          rotation: { x: 0 y: 0.3 z: 0.1 w: 0.2 }
-        }
-        translation_weight: 0.5
-        rotation_weight: 1.0
-        gravity_alignment_first_start { x: 0.4 y: 0.2 z: 0.3 w: 0.2 }
-        gravity_alignment_first_end { x: 0.3 y: 0.4 z: 0.2 w: 0.1 }
-        interpolation_factor: 0.3
-      }
-    }
-  }
-  loss_function { quadratic_loss {} }
-)PROTO";
-
-TEST(InterpolatedRelativePostConstraint2DTest, SerializesCorrectly) {
-  const auto proto = ParseProto<proto::Constraint>(kConstraint);
-  InterpolatedRelativePoseConstraint2D constraint(
-      proto.id(), proto.loss_function(),
-      proto.cost_function().interpolated_relative_pose_2d());
-  const auto actual_proto = constraint.ToProto();
-  EXPECT_THAT(actual_proto, EqualsProto(kConstraint));
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.cc b/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.cc
deleted file mode 100644
index 73f31fa..0000000
--- a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.cc
+++ /dev/null
@@ -1,77 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.h"
-
-#include "absl/memory/memory.h"
-#include "cartographer/common/utils.h"
-#include "cartographer/pose_graph/constraint/constraint_utils.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-InterpolatedRelativePoseConstraint3D::InterpolatedRelativePoseConstraint3D(
-    const ConstraintId& id, const proto::LossFunction& loss_function_proto,
-    const proto::InterpolatedRelativePose3D& proto)
-    : Constraint(id, loss_function_proto),
-      first_start_(proto.first_start()),
-      first_end_(proto.first_end()),
-      second_(proto.second()),
-      cost_(new InterpolatedRelativePoseCost3D(proto.parameters())),
-      ceres_cost_(absl::make_unique<AutoDiffFunction>(cost_)) {}
-
-void InterpolatedRelativePoseConstraint3D::AddToSolver(
-    Nodes* nodes, ceres::Problem* problem) const {
-  FIND_NODE_OR_RETURN(first_node_start, first_start_, nodes->pose_3d_nodes,
-                      "First node (start) was not found in pose_3d_nodes.");
-  FIND_NODE_OR_RETURN(first_node_end, first_end_, nodes->pose_3d_nodes,
-                      "First node (end) was not found in pose_3d_nodes.");
-  FIND_NODE_OR_RETURN(second_node, second_, nodes->pose_3d_nodes,
-                      "Second node was not found in pose_3d_nodes.");
-
-  if (first_node_start->constant() && first_node_end->constant() &&
-      second_node->constant()) {
-    LOG(INFO) << "All nodes are constant, skipping the constraint.";
-    return;
-  }
-
-  AddPose3D(first_node_start, problem);
-  AddPose3D(first_node_end, problem);
-  AddPose3D(second_node, problem);
-  problem->AddResidualBlock(ceres_cost_.get(), ceres_loss(),
-                            first_node_start->mutable_translation()->data(),
-                            first_node_start->mutable_rotation()->data(),
-                            first_node_end->mutable_translation()->data(),
-                            first_node_end->mutable_rotation()->data(),
-                            second_node->mutable_translation()->data(),
-                            second_node->mutable_rotation()->data());
-}
-
-proto::CostFunction InterpolatedRelativePoseConstraint3D::ToCostFunctionProto()
-    const {
-  proto::CostFunction cost_function;
-  auto* interpolated_relative_pose_3d =
-      cost_function.mutable_interpolated_relative_pose_3d();
-  *interpolated_relative_pose_3d->mutable_first_start() =
-      first_start_.ToProto();
-  *interpolated_relative_pose_3d->mutable_first_end() = first_end_.ToProto();
-  *interpolated_relative_pose_3d->mutable_second() = second_.ToProto();
-  *interpolated_relative_pose_3d->mutable_parameters() = cost_->ToProto();
-  return cost_function;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.h b/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.h
deleted file mode 100644
index d836561..0000000
--- a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.h
+++ /dev/null
@@ -1,61 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_INTERPOLATED_RELATIVE_POSE_CONSTRAINT_3D_H_
-#define CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_INTERPOLATED_RELATIVE_POSE_CONSTRAINT_3D_H_
-
-#include "cartographer/pose_graph/constraint/constraint.h"
-#include "cartographer/pose_graph/constraint/cost_function/interpolated_relative_pose_cost_3d.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-class InterpolatedRelativePoseConstraint3D : public Constraint {
- public:
-  InterpolatedRelativePoseConstraint3D(
-      const ConstraintId& id, const proto::LossFunction& loss_function_proto,
-      const proto::InterpolatedRelativePose3D& proto);
-
-  void AddToSolver(Nodes* nodes, ceres::Problem* problem) const final;
-
- protected:
-  proto::CostFunction ToCostFunctionProto() const final;
-
- private:
-  // clang-format off
-  using AutoDiffFunction = ceres::AutoDiffCostFunction<
-      InterpolatedRelativePoseCost3D,
-      6 /* number of residuals */,
-      3 /* translation of first start pose */,
-      4 /* rotation of first start pose */,
-      3 /* translation of first end pose */,
-      4 /* rotation of first end pose */,
-      3 /* translation of second pose */,
-      4 /* rotation of second pose */>;
-  // clang-format on
-  NodeId first_start_;
-  NodeId first_end_;
-  NodeId second_;
-
-  // The cost function is owned by the ceres cost function.
-  InterpolatedRelativePoseCost3D* const cost_;
-  std::unique_ptr<AutoDiffFunction> ceres_cost_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_INTERPOLATED_RELATIVE_POSE_CONSTRAINT_3D_H_
diff --git a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d_test.cc b/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d_test.cc
deleted file mode 100644
index 642188a..0000000
--- a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d_test.cc
+++ /dev/null
@@ -1,67 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.h"
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using ::testing::ElementsAre;
-using testing::EqualsProto;
-using testing::Near;
-using testing::ParseProto;
-
-using PositionType = std::array<double, 3>;
-using RotationType = std::array<double, 4>;
-using ResidualType = std::array<double, 3>;
-
-constexpr char kConstraint[] = R"PROTO(
-  id: "narf"
-  cost_function {
-    interpolated_relative_pose_3d {
-      first_start { object_id: "node0_start" }
-      first_end { object_id: "node0_end" }
-      second { object_id: "node1" }
-      parameters {
-        first_t_second {
-          translation: { x: 1 y: 2 z: 3 }
-          rotation: { x: 0 y: 0.3 z: 0.1 w: 0.2 }
-        }
-        translation_weight: 0.5
-        rotation_weight: 1.0
-        interpolation_factor: 0.3
-      }
-    }
-  }
-
-  loss_function { quadratic_loss {} }
-)PROTO";
-
-TEST(InterpolatedRelativePostConstraint3DTest, SerializesCorrectly) {
-  const auto proto = ParseProto<proto::Constraint>(kConstraint);
-  InterpolatedRelativePoseConstraint3D constraint(
-      proto.id(), proto.loss_function(),
-      proto.cost_function().interpolated_relative_pose_3d());
-  const auto actual_proto = constraint.ToProto();
-  EXPECT_THAT(actual_proto, EqualsProto(kConstraint));
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/loss_function/loss_function.cc b/cartographer/pose_graph/constraint/loss_function/loss_function.cc
deleted file mode 100644
index 6620520..0000000
--- a/cartographer/pose_graph/constraint/loss_function/loss_function.cc
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/loss_function/loss_function.h"
-
-#include "absl/memory/memory.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-std::unique_ptr<ceres::LossFunction> CeresLossFromProto(
-    const proto::LossFunction& proto) {
-  switch (proto.Type_case()) {
-    case proto::LossFunction::kHuberLoss:
-      return absl::make_unique<ceres::HuberLoss>(proto.huber_loss().scale());
-    case proto::LossFunction::kQuadraticLoss:
-      return nullptr;
-    default:
-      LOG(FATAL) << "The loss function is not specified.";
-      return nullptr;
-  }
-}
-
-}  // namespace
-
-LossFunction::LossFunction(const proto::LossFunction& proto)
-    : proto_(proto), ceres_loss_(CeresLossFromProto(proto_)) {}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/loss_function/loss_function.h b/cartographer/pose_graph/constraint/loss_function/loss_function.h
deleted file mode 100644
index 5cbd533..0000000
--- a/cartographer/pose_graph/constraint/loss_function/loss_function.h
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_LOSS_FUNCTION_H_
-#define CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_LOSS_FUNCTION_H_
-
-#include <memory>
-
-#include "cartographer/pose_graph/proto/loss_function.pb.h"
-#include "ceres/loss_function.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-class LossFunction {
- public:
-  explicit LossFunction(const proto::LossFunction& proto);
-
-  const proto::LossFunction& ToProto() const { return proto_; }
-
-  ceres::LossFunction* ceres_loss() const { return ceres_loss_.get(); }
-
- private:
-  const proto::LossFunction proto_;
-  const std::unique_ptr<ceres::LossFunction> ceres_loss_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_LOSS_FUNCTION_H_
diff --git a/cartographer/pose_graph/constraint/loss_function/loss_function_test.cc b/cartographer/pose_graph/constraint/loss_function/loss_function_test.cc
deleted file mode 100644
index 9f29be1..0000000
--- a/cartographer/pose_graph/constraint/loss_function/loss_function_test.cc
+++ /dev/null
@@ -1,45 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/loss_function/loss_function.h"
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using testing::ParseProto;
-
-TEST(LossFunctionTest, ConstructQuadraticLoss) {
-  LossFunction quadratic_loss(
-      ParseProto<proto::LossFunction>(R"(quadratic_loss: {})"));
-  EXPECT_EQ(nullptr, quadratic_loss.ceres_loss());
-}
-
-TEST(LossFunctionTest, ConstructHuberLoss) {
-  LossFunction huber_loss(
-      ParseProto<proto::LossFunction>(R"(huber_loss: { scale: 0.5 })"));
-  EXPECT_NE(nullptr, dynamic_cast<ceres::HuberLoss*>(huber_loss.ceres_loss()));
-}
-
-TEST(LossFunctionDeathTest, FailToConstructUnspecifiedLoss) {
-  EXPECT_DEATH(LossFunction(proto::LossFunction{}), "");
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/relative_pose_constraint_2d.cc b/cartographer/pose_graph/constraint/relative_pose_constraint_2d.cc
deleted file mode 100644
index 46f8264..0000000
--- a/cartographer/pose_graph/constraint/relative_pose_constraint_2d.cc
+++ /dev/null
@@ -1,72 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/relative_pose_constraint_2d.h"
-
-#include "absl/memory/memory.h"
-#include "cartographer/common/utils.h"
-#include "cartographer/pose_graph/constraint/constraint_utils.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-RelativePoseConstraint2D::RelativePoseConstraint2D(
-    const ConstraintId& id, const proto::LossFunction& loss_function_proto,
-    const proto::RelativePose2D& proto)
-    : Constraint(id, loss_function_proto),
-      first_(proto.first()),
-      second_(proto.second()),
-      ceres_cost_(absl::make_unique<RelativePoseCost2D>(proto.parameters())) {}
-
-// TODO(pifon): Add a test.
-void RelativePoseConstraint2D::AddToSolver(Nodes* nodes,
-                                           ceres::Problem* problem) const {
-  FIND_NODE_OR_RETURN(first_node, first_, nodes->pose_2d_nodes,
-                      "First node was not found in pose_2d_nodes.");
-  FIND_NODE_OR_RETURN(second_node, second_, nodes->pose_2d_nodes,
-                      "Second node was not found in pose_2d_nodes.");
-
-  if (first_node->constant() && second_node->constant()) {
-    LOG(INFO) << "Both nodes are constant, skipping the constraint.";
-    return;
-  }
-
-  auto first_pose = first_node->mutable_pose_2d();
-  problem->AddParameterBlock(first_pose->data(), first_pose->size());
-  if (first_node->constant()) {
-    problem->SetParameterBlockConstant(first_pose->data());
-  }
-
-  auto second_pose = second_node->mutable_pose_2d();
-  problem->AddParameterBlock(second_pose->data(), second_pose->size());
-  if (second_node->constant()) {
-    problem->SetParameterBlockConstant(second_pose->data());
-  }
-  problem->AddResidualBlock(ceres_cost_.get(), ceres_loss(), first_pose->data(),
-                            second_pose->data());
-}
-
-proto::CostFunction RelativePoseConstraint2D::ToCostFunctionProto() const {
-  proto::CostFunction cost_function;
-  auto* relative_pose_2d = cost_function.mutable_relative_pose_2d();
-  *relative_pose_2d->mutable_first() = first_.ToProto();
-  *relative_pose_2d->mutable_second() = second_.ToProto();
-  *relative_pose_2d->mutable_parameters() = ceres_cost_->ToProto();
-  return cost_function;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/relative_pose_constraint_2d.h b/cartographer/pose_graph/constraint/relative_pose_constraint_2d.h
deleted file mode 100644
index 23c0bff..0000000
--- a/cartographer/pose_graph/constraint/relative_pose_constraint_2d.h
+++ /dev/null
@@ -1,46 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_RELATIVE_POSE_CONSTRAINT_2D_H_
-#define CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_RELATIVE_POSE_CONSTRAINT_2D_H_
-
-#include "cartographer/pose_graph/constraint/constraint.h"
-#include "cartographer/pose_graph/constraint/cost_function/relative_pose_cost_2d.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-class RelativePoseConstraint2D : public Constraint {
- public:
-  RelativePoseConstraint2D(const ConstraintId& id,
-                           const proto::LossFunction& loss_function_proto,
-                           const proto::RelativePose2D& proto);
-
-  void AddToSolver(Nodes* nodes, ceres::Problem* problem) const final;
-
- protected:
-  proto::CostFunction ToCostFunctionProto() const final;
-
- private:
-  NodeId first_;
-  NodeId second_;
-  std::unique_ptr<RelativePoseCost2D> ceres_cost_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_RELATIVE_POSE_CONSTRAINT_2D_H_
diff --git a/cartographer/pose_graph/constraint/relative_pose_constraint_2d_test.cc b/cartographer/pose_graph/constraint/relative_pose_constraint_2d_test.cc
deleted file mode 100644
index 85c396e..0000000
--- a/cartographer/pose_graph/constraint/relative_pose_constraint_2d_test.cc
+++ /dev/null
@@ -1,58 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/relative_pose_constraint_2d.h"
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using testing::EqualsProto;
-using testing::ParseProto;
-
-constexpr char kConstraint[] = R"PROTO(
-  id: "narf"
-  cost_function {
-    relative_pose_2d {
-      first { object_id: "node0" }
-      second { object_id: "node1" }
-      parameters {
-        first_t_second {
-          translation: { x: 1 y: 1 }
-          rotation: -2.214297
-        }
-        translation_weight: 1
-        rotation_weight: 10
-      }
-    }
-  }
-
-  loss_function { quadratic_loss {} }
-)PROTO";
-
-TEST(RelativePoseConstraint2DTest, SerializesCorrectly) {
-  const auto proto = ParseProto<proto::Constraint>(kConstraint);
-  RelativePoseConstraint2D constraint(proto.id(), proto.loss_function(),
-                                      proto.cost_function().relative_pose_2d());
-  const auto actual_proto = constraint.ToProto();
-  EXPECT_THAT(actual_proto, EqualsProto(kConstraint));
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/relative_pose_constraint_3d.cc b/cartographer/pose_graph/constraint/relative_pose_constraint_3d.cc
deleted file mode 100644
index e688118..0000000
--- a/cartographer/pose_graph/constraint/relative_pose_constraint_3d.cc
+++ /dev/null
@@ -1,66 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/relative_pose_constraint_3d.h"
-
-#include "absl/memory/memory.h"
-#include "cartographer/common/utils.h"
-#include "cartographer/pose_graph/constraint/constraint_utils.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-RelativePoseConstraint3D::RelativePoseConstraint3D(
-    const ConstraintId& id, const proto::LossFunction& loss_function_proto,
-    const proto::RelativePose3D& proto)
-    : Constraint(id, loss_function_proto),
-      first_(proto.first()),
-      second_(proto.second()),
-      cost_(new RelativePoseCost3D(proto.parameters())),
-      ceres_cost_(absl::make_unique<AutoDiffFunction>(cost_)) {}
-
-void RelativePoseConstraint3D::AddToSolver(Nodes* nodes,
-                                           ceres::Problem* problem) const {
-  FIND_NODE_OR_RETURN(first_node, first_, nodes->pose_3d_nodes,
-                      "First node was not found in pose_3d_nodes.");
-  FIND_NODE_OR_RETURN(second_node, second_, nodes->pose_3d_nodes,
-                      "Second node was not found in pose_3d_nodes.");
-
-  if (first_node->constant() && second_node->constant()) {
-    LOG(INFO) << "Both nodes are constant, skipping the constraint.";
-    return;
-  }
-
-  AddPose3D(first_node, problem);
-  AddPose3D(second_node, problem);
-  problem->AddResidualBlock(ceres_cost_.get(), ceres_loss(),
-                            first_node->mutable_translation()->data(),
-                            first_node->mutable_rotation()->data(),
-                            second_node->mutable_translation()->data(),
-                            second_node->mutable_rotation()->data());
-}
-
-proto::CostFunction RelativePoseConstraint3D::ToCostFunctionProto() const {
-  proto::CostFunction cost_function;
-  auto* relative_pose_3d = cost_function.mutable_relative_pose_3d();
-  *relative_pose_3d->mutable_first() = first_.ToProto();
-  *relative_pose_3d->mutable_second() = second_.ToProto();
-  *relative_pose_3d->mutable_parameters() = cost_->ToProto();
-  return cost_function;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/relative_pose_constraint_3d.h b/cartographer/pose_graph/constraint/relative_pose_constraint_3d.h
deleted file mode 100644
index aadc066..0000000
--- a/cartographer/pose_graph/constraint/relative_pose_constraint_3d.h
+++ /dev/null
@@ -1,55 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_RELATIVE_POSE_CONSTRAINT_3D_H_
-#define CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_RELATIVE_POSE_CONSTRAINT_3D_H_
-
-#include "cartographer/pose_graph/constraint/constraint.h"
-#include "cartographer/pose_graph/constraint/cost_function/relative_pose_cost_3d.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-class RelativePoseConstraint3D : public Constraint {
- public:
-  RelativePoseConstraint3D(const ConstraintId& id,
-                           const proto::LossFunction& loss_function_proto,
-                           const proto::RelativePose3D& proto);
-
-  void AddToSolver(Nodes* nodes, ceres::Problem* problem) const final;
-
- protected:
-  proto::CostFunction ToCostFunctionProto() const final;
-
- private:
-  using AutoDiffFunction =
-      ceres::AutoDiffCostFunction<RelativePoseCost3D,
-                                  6 /* number of residuals */,
-                                  3 /* translation variables first pose */,
-                                  4 /* rotation variables first pose*/,
-                                  3 /* translation variables second pose */,
-                                  4 /* rotation variables second pose*/>;
-  NodeId first_;
-  NodeId second_;
-  // The cost function is owned by the ceres cost function.
-  RelativePoseCost3D* const cost_;
-  std::unique_ptr<AutoDiffFunction> ceres_cost_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_RELATIVE_POSE_CONSTRAINT_3D_H_
diff --git a/cartographer/pose_graph/constraint/relative_pose_constraint_3d_test.cc b/cartographer/pose_graph/constraint/relative_pose_constraint_3d_test.cc
deleted file mode 100644
index 6af981b..0000000
--- a/cartographer/pose_graph/constraint/relative_pose_constraint_3d_test.cc
+++ /dev/null
@@ -1,58 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/relative_pose_constraint_3d.h"
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using testing::EqualsProto;
-using testing::ParseProto;
-
-constexpr char kConstraint[] = R"PROTO(
-  id: "narf"
-  cost_function {
-    relative_pose_3d {
-      first { object_id: "node0" }
-      second { object_id: "node1" }
-      parameters {
-        first_t_second {
-          translation: { x: 1 y: 2 z: 3 }
-          rotation: { x: 0 y: 0.3 z: 0.1 w: 0.2 }
-        }
-        translation_weight: 1
-        rotation_weight: 10
-      }
-    }
-  }
-
-  loss_function { quadratic_loss {} }
-)PROTO";
-
-TEST(RelativePoseConstraint2DTest, SerializesCorrectly) {
-  const auto proto = ParseProto<proto::Constraint>(kConstraint);
-  RelativePoseConstraint3D constraint(proto.id(), proto.loss_function(),
-                                      proto.cost_function().relative_pose_3d());
-  const auto actual_proto = constraint.ToProto();
-  EXPECT_THAT(actual_proto, EqualsProto(kConstraint));
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/rotation_constraint_3d.cc b/cartographer/pose_graph/constraint/rotation_constraint_3d.cc
deleted file mode 100644
index b9bf6ee..0000000
--- a/cartographer/pose_graph/constraint/rotation_constraint_3d.cc
+++ /dev/null
@@ -1,91 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/rotation_constraint_3d.h"
-
-#include "absl/memory/memory.h"
-#include "cartographer/pose_graph/constraint/constraint_utils.h"
-
-#include "cartographer/common/utils.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-void AddRotation3D(Pose3D* pose, ceres::Problem* problem) {
-  auto rotation = pose->mutable_rotation();
-  problem->AddParameterBlock(rotation->data(), rotation->size());
-  if (pose->constant()) {
-    problem->SetParameterBlockConstant(rotation->data());
-  }
-}
-
-void AddImuOrientation(ImuCalibration* imu_node, ceres::Problem* problem) {
-  auto imu_orientation = imu_node->mutable_orientation();
-  problem->AddParameterBlock(imu_orientation->data(), imu_orientation->size());
-  if (imu_node->constant()) {
-    problem->SetParameterBlockConstant(imu_orientation->data());
-  }
-}
-
-}  // namespace
-
-RotationContraint3D::RotationContraint3D(
-    const ConstraintId& id, const proto::LossFunction& loss_function_proto,
-    const proto::Rotation3D& proto)
-    : Constraint(id, loss_function_proto),
-      first_(proto.first()),
-      second_(proto.second()),
-      imu_calibration_(proto.imu_calibration()),
-      cost_(new RotationCost3D(proto.parameters())),
-      ceres_cost_(absl::make_unique<AutoDiffFunction>(cost_)) {}
-
-void RotationContraint3D::AddToSolver(Nodes* nodes,
-                                      ceres::Problem* problem) const {
-  FIND_NODE_OR_RETURN(first_node, first_, nodes->pose_3d_nodes,
-                      "First node was not found in pose_3d_nodes.");
-  FIND_NODE_OR_RETURN(second_node, second_, nodes->pose_3d_nodes,
-                      "Second node was not found in pose_3d_nodes.");
-  FIND_NODE_OR_RETURN(imu_node, imu_calibration_, nodes->imu_calibration_nodes,
-                      "Imu calibration node was not found.");
-
-  if (first_node->constant() && second_node->constant() &&
-      imu_node->constant()) {
-    LOG(INFO) << "Both nodes are constant, skipping the constraint.";
-    return;
-  }
-
-  AddRotation3D(first_node, problem);
-  AddRotation3D(second_node, problem);
-  AddImuOrientation(imu_node, problem);
-  problem->AddResidualBlock(ceres_cost_.get(), ceres_loss(),
-                            first_node->mutable_rotation()->data(),
-                            second_node->mutable_rotation()->data(),
-                            imu_node->mutable_orientation()->data());
-}
-
-proto::CostFunction RotationContraint3D::ToCostFunctionProto() const {
-  proto::CostFunction cost_function;
-  auto* rotation_3d = cost_function.mutable_rotation_3d();
-  *rotation_3d->mutable_first() = first_.ToProto();
-  *rotation_3d->mutable_second() = second_.ToProto();
-  *rotation_3d->mutable_imu_calibration() = imu_calibration_.ToProto();
-  *rotation_3d->mutable_parameters() = cost_->ToProto();
-  return cost_function;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/constraint/rotation_constraint_3d.h b/cartographer/pose_graph/constraint/rotation_constraint_3d.h
deleted file mode 100644
index b0dbe24..0000000
--- a/cartographer/pose_graph/constraint/rotation_constraint_3d.h
+++ /dev/null
@@ -1,52 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_ROTATION_CONSTRAINT_3D_H_
-#define CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_ROTATION_CONSTRAINT_3D_H_
-
-#include "cartographer/pose_graph/constraint/constraint.h"
-#include "cartographer/pose_graph/constraint/cost_function/rotation_cost_3d.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-class RotationContraint3D : public Constraint {
- public:
-  RotationContraint3D(const ConstraintId& id,
-                      const proto::LossFunction& loss_function_proto,
-                      const proto::Rotation3D& proto);
-
-  void AddToSolver(Nodes* nodes, ceres::Problem* problem) const final;
-
- protected:
-  proto::CostFunction ToCostFunctionProto() const final;
-
- private:
-  using AutoDiffFunction = ceres::AutoDiffCostFunction<
-      RotationCost3D, 3 /* number of residuals */, 4 /* rotation first pose */,
-      4 /* rotation second pose */, 4 /* imu calibration */>;
-  NodeId first_;
-  NodeId second_;
-  NodeId imu_calibration_;
-  // The cost function is owned by the ceres cost function.
-  RotationCost3D* const cost_;
-  std::unique_ptr<AutoDiffFunction> ceres_cost_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_CONSTRAINT_ROTATION_CONSTRAINT_3D_H_
diff --git a/cartographer/pose_graph/constraint/rotation_constraint_3d_test.cc b/cartographer/pose_graph/constraint/rotation_constraint_3d_test.cc
deleted file mode 100644
index 0c2d861..0000000
--- a/cartographer/pose_graph/constraint/rotation_constraint_3d_test.cc
+++ /dev/null
@@ -1,54 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/constraint/rotation_constraint_3d.h"
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using testing::EqualsProto;
-using testing::ParseProto;
-
-constexpr char kConstraint[] = R"PROTO(
-  id: "narf"
-  cost_function {
-    rotation_3d {
-      first { object_id: "node0" }
-      second { object_id: "node1" }
-      imu_calibration { object_id: "imu_node" }
-      parameters {
-        delta_rotation_imu_frame { x: 0 y: 0.1 z: 0.2 w: 0.3 }
-        scaling_factor: 0.4
-      }
-    }
-  }
-  loss_function { quadratic_loss {} }
-)PROTO";
-
-TEST(RotationConstraint3DTest, SerializesCorrectly) {
-  const auto proto = ParseProto<proto::Constraint>(kConstraint);
-  RotationContraint3D constraint(proto.id(), proto.loss_function(),
-                                 proto.cost_function().rotation_3d());
-  const auto actual_proto = constraint.ToProto();
-  EXPECT_THAT(actual_proto, EqualsProto(kConstraint));
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/node/imu_calibration.cc b/cartographer/pose_graph/node/imu_calibration.cc
deleted file mode 100644
index 3389c7d..0000000
--- a/cartographer/pose_graph/node/imu_calibration.cc
+++ /dev/null
@@ -1,50 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/node/imu_calibration.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-ImuCalibration::ImuCalibration(const NodeId& node_id, bool constant,
-                               const proto::ImuCalibration& imu)
-    : Node(node_id, constant),
-      gravity_constant_(imu.gravity_constant()),
-      orientation_{{imu.orientation().x(), imu.orientation().y(),
-                    imu.orientation().z(), imu.orientation().w()}},
-      orientation_parameterization_(imu.orientation_parameterization()) {}
-
-proto::Parameters ImuCalibration::ToParametersProto() const {
-  proto::Parameters parameters;
-  auto* imu_calibration = parameters.mutable_imu_calibration();
-
-  imu_calibration->set_gravity_constant(gravity_constant_);
-
-  // TODO(pifon): Use a common method to convert from Eigen::Quaterniond to
-  // proto. Probably, the one defined in transform.h.
-  auto* orientation = imu_calibration->mutable_orientation();
-  orientation->set_x(orientation_[0]);
-  orientation->set_y(orientation_[1]);
-  orientation->set_z(orientation_[2]);
-  orientation->set_w(orientation_[3]);
-  imu_calibration->set_orientation_parameterization(
-      orientation_parameterization_.ToProto());
-
-  return parameters;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/node/imu_calibration.h b/cartographer/pose_graph/node/imu_calibration.h
deleted file mode 100644
index 6febd5b..0000000
--- a/cartographer/pose_graph/node/imu_calibration.h
+++ /dev/null
@@ -1,57 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_NODE_IMU_CALIBRATION_H_
-#define CARTOGRAPHER_POSE_GRAPH_NODE_IMU_CALIBRATION_H_
-
-#include "cartographer/pose_graph/node/node.h"
-
-#include <array>
-
-#include "cartographer/pose_graph/node/parameterization/parameterization.h"
-#include "cartographer/transform/transform.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-class ImuCalibration : public Node {
- public:
-  ImuCalibration(const NodeId& node_id, bool constant,
-                 const proto::ImuCalibration& imu_calibration);
-
-  double* mutable_gravity_constant() { return &gravity_constant_; }
-  double gravity_constant() const { return gravity_constant_; }
-
-  std::array<double, 4>* mutable_orientation() { return &orientation_; }
-  const std::array<double, 4>& orientation() const { return orientation_; }
-
-  ceres::LocalParameterization* orientation_parameterization() const {
-    return orientation_parameterization_.ceres_parameterization();
-  }
-
- protected:
-  proto::Parameters ToParametersProto() const final;
-
- private:
-  double gravity_constant_;
-  std::array<double, 4> orientation_;
-  Parameterization orientation_parameterization_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_NODE_IMU_CALIBRATION_H_
diff --git a/cartographer/pose_graph/node/imu_calibration_test.cc b/cartographer/pose_graph/node/imu_calibration_test.cc
deleted file mode 100644
index 1894043..0000000
--- a/cartographer/pose_graph/node/imu_calibration_test.cc
+++ /dev/null
@@ -1,51 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/node/imu_calibration.h"
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using testing::ParseProto;
-
-constexpr char kExpectedNode[] = R"PROTO(
-  id { object_id: "accelerometer" timestamp: 1 }
-  constant: true
-  parameters {
-    imu_calibration {
-      gravity_constant: 10
-      orientation: { w: 0 x: 1 y: 2 z: 3 }
-      orientation_parameterization: YAW_ONLY
-    }
-  }
-)PROTO";
-
-TEST(Pose3DTest, ToProto) {
-  ImuCalibration imu_calibration({"accelerometer", common::FromUniversal(1)},
-                                 true, ParseProto<proto::ImuCalibration>(R"(
-                                     gravity_constant: 10
-                                     orientation: { w: 0 x: 1 y: 2 z: 3 }
-                                     orientation_parameterization: YAW_ONLY
-                                   )"));
-  EXPECT_THAT(imu_calibration.ToProto(), testing::EqualsProto(kExpectedNode));
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/node/node.cc b/cartographer/pose_graph/node/node.cc
deleted file mode 100644
index b9293f1..0000000
--- a/cartographer/pose_graph/node/node.cc
+++ /dev/null
@@ -1,31 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/node/node.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-proto::Node Node::ToProto() const {
-  proto::Node node;
-  node.set_constant(constant_);
-  *node.mutable_id() = node_id_.ToProto();
-  *node.mutable_parameters() = ToParametersProto();
-  return node;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/node/node.h b/cartographer/pose_graph/node/node.h
deleted file mode 100644
index 8e29ea6..0000000
--- a/cartographer/pose_graph/node/node.h
+++ /dev/null
@@ -1,53 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_NODE_NODE_H_
-#define CARTOGRAPHER_POSE_GRAPH_NODE_NODE_H_
-
-#include "cartographer/pose_graph/node/node_id.h"
-#include "cartographer/pose_graph/proto/node.pb.h"
-
-#include <vector>
-
-namespace cartographer {
-namespace pose_graph {
-
-class Node {
- public:
-  explicit Node(const NodeId& id, bool constant)
-      : node_id_(id), constant_(constant) {}
-
-  ~Node() = default;
-
-  proto::Node ToProto() const;
-
-  const NodeId node_id() const { return node_id_; }
-
-  bool constant() const { return constant_; }
-  void set_constant(bool constant) { constant_ = constant; }
-
- protected:
-  virtual proto::Parameters ToParametersProto() const = 0;
-
- private:
-  NodeId node_id_;
-  bool constant_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_NODE_NODE_H_
diff --git a/cartographer/pose_graph/node/node_id.cc b/cartographer/pose_graph/node/node_id.cc
deleted file mode 100644
index b242b33..0000000
--- a/cartographer/pose_graph/node/node_id.cc
+++ /dev/null
@@ -1,42 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/node/node_id.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-NodeId::NodeId(const std::string& object_id, common::Time time)
-    : object_id(object_id), time(time) {}
-
-NodeId::NodeId(const std::string& object_id, const std::string& group_id,
-               common::Time time)
-    : object_id(object_id), group_id(group_id), time(time) {}
-
-NodeId::NodeId(const proto::NodeId& node_id)
-    : NodeId(node_id.object_id(), node_id.group_id(),
-             common::FromUniversal(node_id.timestamp())) {}
-
-proto::NodeId NodeId::ToProto() const {
-  proto::NodeId node_id;
-  node_id.set_object_id(object_id);
-  node_id.set_group_id(group_id);
-  node_id.set_timestamp(common::ToUniversal(time));
-  return node_id;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/node/node_id.h b/cartographer/pose_graph/node/node_id.h
deleted file mode 100644
index ecb62b1..0000000
--- a/cartographer/pose_graph/node/node_id.h
+++ /dev/null
@@ -1,63 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_NODE_NODE_ID_
-#define CARTOGRAPHER_POSE_GRAPH_NODE_NODE_ID_
-
-#include <ostream>
-#include <string>
-
-#include "cartographer/common/time.h"
-#include "cartographer/pose_graph/proto/node.pb.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-struct NodeId {
-  NodeId(const std::string& object_id, common::Time time);
-  NodeId(const std::string& object_id, const std::string& group_id,
-         common::Time time);
-  explicit NodeId(const proto::NodeId& node_id);
-
-  // Object refers to dynamic/static objects, e.g. robot/landmark/submap poses,
-  // IMU calibration, etc.
-  std::string object_id;
-  // Id of the group to which the node belongs, e.g. "submap".
-  std::string group_id;
-  // Time associated with the object's pose.
-  common::Time time;
-
-  proto::NodeId ToProto() const;
-};
-
-inline bool operator<(const NodeId& lhs, const NodeId& rhs) {
-  return std::forward_as_tuple(lhs.object_id, lhs.group_id, lhs.time) <
-         std::forward_as_tuple(rhs.object_id, rhs.group_id, rhs.time);
-}
-
-inline std::ostream& operator<<(std::ostream& os, const NodeId& id) {
-  std::string group_message;
-  if (!id.group_id.empty()) {
-    group_message = ", group_id: " + id.group_id;
-  }
-  return os << "(object_id: " << id.object_id << group_message
-            << ", time: " << id.time << ")";
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_NODE_NODE_ID_
diff --git a/cartographer/pose_graph/node/node_id_test.cc b/cartographer/pose_graph/node/node_id_test.cc
deleted file mode 100644
index 37a5a18..0000000
--- a/cartographer/pose_graph/node/node_id_test.cc
+++ /dev/null
@@ -1,62 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/node/node_id.h"
-
-#include <sstream>
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-TEST(NodeIdTest, FromProto) {
-  proto::NodeId proto;
-  proto.set_object_id("some_object");
-  proto.set_group_id("submap");
-  proto.set_timestamp(1);
-
-  NodeId node_id(proto);
-  EXPECT_EQ(node_id.object_id, "some_object");
-  EXPECT_EQ(node_id.group_id, "submap");
-  EXPECT_EQ(common::ToUniversal(node_id.time), 1);
-}
-
-TEST(NodeIdTest, ToProto) {
-  NodeId node_id{"some_object", "submap", common::FromUniversal(1)};
-  EXPECT_THAT(node_id.ToProto(),
-              testing::EqualsProto(
-                  "object_id: 'some_object' group_id: 'submap' timestamp: 1"));
-}
-
-TEST(NodeIdTest, ToStringWithoutGroupId) {
-  std::stringstream ss;
-  ss << NodeId{"some_object", common::FromUniversal(1)};
-
-  EXPECT_EQ("(object_id: some_object, time: 1)", ss.str());
-}
-
-TEST(NodeIdTest, ToStringWithGroupId) {
-  std::stringstream ss;
-  ss << NodeId{"some_object", "submap", common::FromUniversal(1)};
-
-  EXPECT_EQ("(object_id: some_object, group_id: submap, time: 1)", ss.str());
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/node/nodes.h b/cartographer/pose_graph/node/nodes.h
deleted file mode 100644
index 21f9860..0000000
--- a/cartographer/pose_graph/node/nodes.h
+++ /dev/null
@@ -1,39 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_NODE_NODES_H_
-#define CARTOGRAPHER_POSE_GRAPH_NODE_NODES_H_
-
-#include "cartographer/pose_graph/node/imu_calibration.h"
-#include "cartographer/pose_graph/node/pose_2d.h"
-#include "cartographer/pose_graph/node/pose_3d.h"
-
-#include <map>
-
-namespace cartographer {
-namespace pose_graph {
-
-struct Nodes {
-  // TODO(pifon): Migrate to Swiss Tables when they are out.
-  std::map<NodeId, std::unique_ptr<Pose2D>> pose_2d_nodes;
-  std::map<NodeId, std::unique_ptr<Pose3D>> pose_3d_nodes;
-  std::map<NodeId, std::unique_ptr<ImuCalibration>> imu_calibration_nodes;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_NODE_NODES_H_
diff --git a/cartographer/pose_graph/node/parameterization/parameterization.cc b/cartographer/pose_graph/node/parameterization/parameterization.cc
deleted file mode 100644
index 44a5be4..0000000
--- a/cartographer/pose_graph/node/parameterization/parameterization.cc
+++ /dev/null
@@ -1,61 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/node/parameterization/parameterization.h"
-
-#include "absl/memory/memory.h"
-#include "cartographer/common/math.h"
-#include "cartographer/mapping/internal/3d/rotation_parameterization.h"
-#include "ceres/autodiff_local_parameterization.h"
-#include "ceres/rotation.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using absl::make_unique;
-using ceres::AutoDiffLocalParameterization;
-using ceres::LocalParameterization;
-
-// TODO(pifon): Check if the functors are compatible with our quaternions. Test!
-std::unique_ptr<LocalParameterization> CeresParameterizationFromProto(
-    const proto::Parameterization& parameterization) {
-  switch (parameterization) {
-    case (proto::Parameterization::NONE):
-      return nullptr;
-    case (proto::Parameterization::YAW_ONLY):
-      return make_unique<AutoDiffLocalParameterization<
-          mapping::YawOnlyQuaternionPlus, 4, 1>>();
-    case (proto::Parameterization::YAW_CONSTANT):
-      return make_unique<AutoDiffLocalParameterization<
-          mapping::ConstantYawQuaternionPlus, 4, 1>>();
-    case (proto::Parameterization::FIX_Z):
-      return make_unique<ceres::SubsetParameterization>(
-          3, /* constant parameters */ std::vector<int>{2});
-    default:
-      LOG(FATAL) << "Parameterization is not known.";
-  }
-  return nullptr;
-}
-
-}  // namespace
-
-Parameterization::Parameterization(const proto::Parameterization& proto)
-    : proto_(proto),
-      ceres_parameterization_(CeresParameterizationFromProto(proto_)) {}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/node/parameterization/parameterization.h b/cartographer/pose_graph/node/parameterization/parameterization.h
deleted file mode 100644
index eab1e58..0000000
--- a/cartographer/pose_graph/node/parameterization/parameterization.h
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_NODE_PARAMETERIZATION_PARAMETERIZATION_H_
-#define CARTOGRAPHER_POSE_GRAPH_NODE_PARAMETERIZATION_PARAMETERIZATION_H_
-
-#include "cartographer/pose_graph/proto/node.pb.h"
-#include "ceres/local_parameterization.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-class Parameterization {
- public:
-  explicit Parameterization(const proto::Parameterization& proto);
-
-  const proto::Parameterization& ToProto() const { return proto_; }
-
-  ceres::LocalParameterization* ceres_parameterization() const {
-    return ceres_parameterization_.get();
-  }
-
- private:
-  const proto::Parameterization proto_;
-  const std::unique_ptr<ceres::LocalParameterization> ceres_parameterization_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_NODE_PARAMETERIZATION_PARAMETERIZATION_H_
diff --git a/cartographer/pose_graph/node/pose_2d.cc b/cartographer/pose_graph/node/pose_2d.cc
deleted file mode 100644
index 50cba73..0000000
--- a/cartographer/pose_graph/node/pose_2d.cc
+++ /dev/null
@@ -1,47 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/node/pose_2d.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-constexpr size_t kXIndex = 0;
-constexpr size_t kYIndex = 1;
-constexpr size_t kRotationIndex = 2;
-
-}  // namespace
-
-Pose2D::Pose2D(const NodeId& node_id, bool constant,
-               const proto::Pose2D& pose_2d)
-    : Node(node_id, constant),
-      pose_2d_{{pose_2d.translation().x(), pose_2d.translation().y(),
-                pose_2d.rotation()}} {}
-
-proto::Parameters Pose2D::ToParametersProto() const {
-  proto::Parameters parameters;
-  auto* pose_2d = parameters.mutable_pose_2d();
-  pose_2d->set_rotation(pose_2d_[kRotationIndex]);
-
-  auto* translation = pose_2d->mutable_translation();
-  translation->set_x(pose_2d_[kXIndex]);
-  translation->set_y(pose_2d_[kYIndex]);
-  return parameters;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/node/pose_2d.h b/cartographer/pose_graph/node/pose_2d.h
deleted file mode 100644
index 5b94bb3..0000000
--- a/cartographer/pose_graph/node/pose_2d.h
+++ /dev/null
@@ -1,46 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_NODE_POSE_2D_H_
-#define CARTOGRAPHER_POSE_GRAPH_NODE_POSE_2D_H_
-
-#include "cartographer/pose_graph/node/node.h"
-
-#include <array>
-
-#include "Eigen/Core"
-
-namespace cartographer {
-namespace pose_graph {
-
-class Pose2D : public Node {
- public:
-  Pose2D(const NodeId& node_id, bool constant, const proto::Pose2D& pose_2d);
-
-  std::array<double, 3>* mutable_pose_2d() { return &pose_2d_; }
-  const std::array<double, 3>& pose_2d() const { return pose_2d_; }
-
- protected:
-  proto::Parameters ToParametersProto() const final;
-
- private:
-  std::array<double, 3> pose_2d_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_NODE_POSE_2D_H_
diff --git a/cartographer/pose_graph/node/pose_2d_test.cc b/cartographer/pose_graph/node/pose_2d_test.cc
deleted file mode 100644
index 793277f..0000000
--- a/cartographer/pose_graph/node/pose_2d_test.cc
+++ /dev/null
@@ -1,49 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/node/pose_2d.h"
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using testing::ParseProto;
-
-constexpr char kExpectedNode[] = R"PROTO(
-  id { object_id: "flat_world" timestamp: 1 }
-  constant: true
-  parameters {
-    pose_2d {
-      translation { x: 1 y: 2 }
-      rotation: 5
-    }
-  }
-)PROTO";
-
-TEST(Pose2DTest, ToProto) {
-  Pose2D pose_2d({"flat_world", common::FromUniversal(1)}, true,
-                 ParseProto<proto::Pose2D>(R"(
-                   translation { x: 1 y: 2 }
-                   rotation: 5
-                 )"));
-  EXPECT_THAT(pose_2d.ToProto(), testing::EqualsProto(kExpectedNode));
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/node/pose_3d.cc b/cartographer/pose_graph/node/pose_3d.cc
deleted file mode 100644
index d743e72..0000000
--- a/cartographer/pose_graph/node/pose_3d.cc
+++ /dev/null
@@ -1,54 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/node/pose_3d.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-Pose3D::Pose3D(const NodeId& node_id, bool constant,
-               const proto::Pose3D& pose_3d)
-    : Node(node_id, constant),
-      translation_{{pose_3d.translation().x(), pose_3d.translation().y(),
-                    pose_3d.translation().z()}},
-      translation_parameterization_(pose_3d.translation_parameterization()),
-      rotation_{{pose_3d.rotation().x(), pose_3d.rotation().y(),
-                 pose_3d.rotation().z(), pose_3d.rotation().w()}},
-      rotation_parameterization_(pose_3d.rotation_parameterization()) {}
-
-proto::Parameters Pose3D::ToParametersProto() const {
-  proto::Parameters parameters;
-  auto* pose_3d = parameters.mutable_pose_3d();
-
-  auto* translation = pose_3d->mutable_translation();
-  translation->set_x(translation_[0]);
-  translation->set_y(translation_[1]);
-  translation->set_z(translation_[2]);
-  pose_3d->set_translation_parameterization(
-      translation_parameterization_.ToProto());
-
-  auto* rotation = pose_3d->mutable_rotation();
-  rotation->set_x(rotation_[0]);
-  rotation->set_y(rotation_[1]);
-  rotation->set_z(rotation_[2]);
-  rotation->set_w(rotation_[3]);
-  pose_3d->set_rotation_parameterization(rotation_parameterization_.ToProto());
-
-  return parameters;
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/node/pose_3d.h b/cartographer/pose_graph/node/pose_3d.h
deleted file mode 100644
index 1b09781..0000000
--- a/cartographer/pose_graph/node/pose_3d.h
+++ /dev/null
@@ -1,60 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_NODE_POSE_3D_H_
-#define CARTOGRAPHER_POSE_GRAPH_NODE_POSE_3D_H_
-
-#include "cartographer/pose_graph/node/node.h"
-
-#include <array>
-
-#include "cartographer/pose_graph/node/parameterization/parameterization.h"
-#include "cartographer/transform/transform.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-class Pose3D : public Node {
- public:
-  Pose3D(const NodeId& node_id, bool constant, const proto::Pose3D& pose_3d);
-
-  std::array<double, 3>* mutable_translation() { return &translation_; }
-  const std::array<double, 3>& translation() const { return translation_; }
-  ceres::LocalParameterization* translation_parameterization() const {
-    return translation_parameterization_.ceres_parameterization();
-  }
-
-  std::array<double, 4>* mutable_rotation() { return &rotation_; }
-  const std::array<double, 4>& rotation() const { return rotation_; }
-  ceres::LocalParameterization* rotation_parameterization() const {
-    return rotation_parameterization_.ceres_parameterization();
-  }
-
- protected:
-  proto::Parameters ToParametersProto() const final;
-
- private:
-  std::array<double, 3> translation_;
-  Parameterization translation_parameterization_;
-
-  std::array<double, 4> rotation_;
-  Parameterization rotation_parameterization_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_NODE_POSE_3D_H_
diff --git a/cartographer/pose_graph/node/pose_3d_test.cc b/cartographer/pose_graph/node/pose_3d_test.cc
deleted file mode 100644
index 25b1059..0000000
--- a/cartographer/pose_graph/node/pose_3d_test.cc
+++ /dev/null
@@ -1,52 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/node/pose_3d.h"
-
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using testing::ParseProto;
-
-constexpr char kExpectedNode[] = R"PROTO(
-  id { object_id: "bumpy_world" timestamp: 1 }
-  constant: true
-  parameters {
-    pose_3d {
-      translation { x: 1 y: 2 z: 3 }
-      translation_parameterization: FIX_Z
-      rotation: { w: 0 x: 1 y: 2 z: 3 }
-    }
-  }
-)PROTO";
-
-TEST(Pose3DTest, ToProto) {
-  Pose3D pose_3d({"bumpy_world", common::FromUniversal(1)}, true,
-                 ParseProto<proto::Pose3D>(R"(
-                   translation { x: 1 y: 2 z: 3 }
-                   translation_parameterization: FIX_Z
-                   rotation: { w: 0 x: 1 y: 2 z: 3 }
-                   rotation_parameterization: NONE
-                 )"));
-  EXPECT_THAT(pose_3d.ToProto(), testing::EqualsProto(kExpectedNode));
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/pose_graph_controller.cc b/cartographer/pose_graph/pose_graph_controller.cc
deleted file mode 100644
index 5a7aa2c..0000000
--- a/cartographer/pose_graph/pose_graph_controller.cc
+++ /dev/null
@@ -1,48 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/pose_graph_controller.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-void PoseGraphController::AddData(const proto::PoseGraphData& data) {
-  absl::MutexLock locker(&mutex_);
-  for (const auto& node : data.nodes()) {
-    AddNodeToPoseGraphData(node, &data_);
-  }
-  for (const auto& constraint : data.constraints()) {
-    AddConstraintToPoseGraphData(constraint, &data_);
-  }
-}
-
-void PoseGraphController::AddNode(const proto::Node& node) {
-  absl::MutexLock locker(&mutex_);
-  AddNodeToPoseGraphData(node, &data_);
-}
-
-void PoseGraphController::AddConstraint(const proto::Constraint& constraint) {
-  absl::MutexLock locker(&mutex_);
-  AddConstraintToPoseGraphData(constraint, &data_);
-}
-
-Solver::SolverStatus PoseGraphController::Optimize() {
-  absl::MutexLock locker(&mutex_);
-  return solver_->Solve(&data_);
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/pose_graph_controller.h b/cartographer/pose_graph/pose_graph_controller.h
deleted file mode 100644
index 3c915ed..0000000
--- a/cartographer/pose_graph/pose_graph_controller.h
+++ /dev/null
@@ -1,53 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_POSE_GRAPH_CONTROLLER_H_
-#define CARTOGRAPHER_POSE_GRAPH_POSE_GRAPH_CONTROLLER_H_
-
-#include "absl/synchronization/mutex.h"
-#include "cartographer/pose_graph/pose_graph_data.h"
-#include "cartographer/pose_graph/proto/pose_graph_data.pb.h"
-#include "cartographer/pose_graph/solver/solver.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-class PoseGraphController {
- public:
-  PoseGraphController(std::unique_ptr<Solver> optimizer)
-      : solver_(std::move(optimizer)) {}
-
-  PoseGraphController(const PoseGraphController&) = delete;
-  PoseGraphController& operator=(const PoseGraphController&) = delete;
-
-  void AddData(const proto::PoseGraphData& data) LOCKS_EXCLUDED(mutex_);
-  void AddNode(const proto::Node& node) LOCKS_EXCLUDED(mutex_);
-  void AddConstraint(const proto::Constraint& constraint)
-      LOCKS_EXCLUDED(mutex_);
-
-  Solver::SolverStatus Optimize() LOCKS_EXCLUDED(mutex_);
-
- private:
-  std::unique_ptr<Solver> solver_;
-
-  mutable absl::Mutex mutex_;
-  PoseGraphData data_ GUARDED_BY(mutex_);
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_POSE_GRAPH_CONTROLLER_H_
diff --git a/cartographer/pose_graph/pose_graph_data.cc b/cartographer/pose_graph/pose_graph_data.cc
deleted file mode 100644
index 87686c9..0000000
--- a/cartographer/pose_graph/pose_graph_data.cc
+++ /dev/null
@@ -1,100 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/pose_graph_data.h"
-
-#include "absl/memory/memory.h"
-#include "cartographer/pose_graph/constraint/acceleration_constraint_3d.h"
-#include "cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.h"
-#include "cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.h"
-#include "cartographer/pose_graph/constraint/relative_pose_constraint_2d.h"
-#include "cartographer/pose_graph/constraint/relative_pose_constraint_3d.h"
-#include "cartographer/pose_graph/constraint/rotation_constraint_3d.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using absl::make_unique;
-
-std::unique_ptr<Constraint> CreateConstraint(
-    const proto::Constraint& constraint) {
-  const auto& id = constraint.id();
-  const auto& loss = constraint.loss_function();
-  const auto& cost = constraint.cost_function();
-  switch (cost.type_case()) {
-    case (proto::CostFunction::kRelativePose2D):
-      return make_unique<RelativePoseConstraint2D>(id, loss,
-                                                   cost.relative_pose_2d());
-    case (proto::CostFunction::kRelativePose3D):
-      return make_unique<RelativePoseConstraint3D>(id, loss,
-                                                   cost.relative_pose_3d());
-    case (proto::CostFunction::kAcceleration3D):
-      return make_unique<AccelerationConstraint3D>(id, loss,
-                                                   cost.acceleration_3d());
-    case (proto::CostFunction::kRotation3D):
-      return make_unique<RotationContraint3D>(id, loss, cost.rotation_3d());
-    case (proto::CostFunction::kInterpolatedRelativePose2D):
-      return make_unique<InterpolatedRelativePoseConstraint2D>(
-          id, loss, cost.interpolated_relative_pose_2d());
-    case (proto::CostFunction::kInterpolatedRelativePose3D):
-      return make_unique<InterpolatedRelativePoseConstraint3D>(
-          id, loss, cost.interpolated_relative_pose_3d());
-    case (proto::CostFunction::TYPE_NOT_SET):
-      LOG(FATAL) << "Constraint cost function type is not set.";
-  }
-  return nullptr;
-}
-
-}  // namespace
-
-void AddNodeToPoseGraphData(const proto::Node& node, PoseGraphData* data) {
-  NodeId node_id(node.id());
-  switch (node.parameters().type_case()) {
-    case (proto::Parameters::kPose2D): {
-      data->nodes.pose_2d_nodes.emplace(
-          node_id, make_unique<Pose2D>(node_id, node.constant(),
-                                       node.parameters().pose_2d()));
-      return;
-    }
-    case (proto::Parameters::kPose3D): {
-      data->nodes.pose_3d_nodes.emplace(
-          node_id, make_unique<Pose3D>(node_id, node.constant(),
-                                       node.parameters().pose_3d()));
-
-      return;
-    }
-    case (proto::Parameters::kImuCalibration): {
-      data->nodes.imu_calibration_nodes.emplace(
-          node_id,
-          make_unique<ImuCalibration>(node_id, node.constant(),
-                                      node.parameters().imu_calibration()));
-      return;
-    }
-    case (proto::Parameters::TYPE_NOT_SET): {
-      LOG(FATAL) << "Node parameter type is not set.";
-      return;
-    }
-  }
-}
-
-void AddConstraintToPoseGraphData(const proto::Constraint& constraint,
-                                  PoseGraphData* data) {
-  data->constraints.emplace_back(CreateConstraint(constraint));
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/pose_graph_data.h b/cartographer/pose_graph/pose_graph_data.h
deleted file mode 100644
index 1a6b30c..0000000
--- a/cartographer/pose_graph/pose_graph_data.h
+++ /dev/null
@@ -1,38 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_POSE_GRAPH_DATA_H_
-#define CARTOGRAPHER_POSE_GRAPH_POSE_GRAPH_DATA_H_
-
-#include "cartographer/pose_graph/constraint/constraint.h"
-#include "cartographer/pose_graph/node/nodes.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-struct PoseGraphData {
-  Nodes nodes;
-  std::vector<std::unique_ptr<Constraint>> constraints;
-};
-
-void AddNodeToPoseGraphData(const proto::Node& node, PoseGraphData* data);
-void AddConstraintToPoseGraphData(const proto::Constraint& constraint,
-                                  PoseGraphData* data);
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_POSE_GRAPH_DATA_H_
diff --git a/cartographer/pose_graph/proto/constraint.proto b/cartographer/pose_graph/proto/constraint.proto
deleted file mode 100644
index 44b6d05..0000000
--- a/cartographer/pose_graph/proto/constraint.proto
+++ /dev/null
@@ -1,26 +0,0 @@
-// Copyright 2018 The Cartographer Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-syntax = "proto3";
-
-import "cartographer/pose_graph/proto/loss_function.proto";
-import "cartographer/pose_graph/proto/cost_function.proto";
-
-package cartographer.pose_graph.proto;
-
-message Constraint {
-  string id = 1;
-  CostFunction cost_function = 2;
-  LossFunction loss_function = 3;
-}
diff --git a/cartographer/pose_graph/proto/cost_function.proto b/cartographer/pose_graph/proto/cost_function.proto
deleted file mode 100644
index 877f66f..0000000
--- a/cartographer/pose_graph/proto/cost_function.proto
+++ /dev/null
@@ -1,114 +0,0 @@
-// Copyright 2018 The Cartographer Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-syntax = "proto3";
-
-import "cartographer/pose_graph/proto/node.proto";
-import "cartographer/transform/proto/transform.proto";
-
-package cartographer.pose_graph.proto;
-
-message RelativePose2D {
-  NodeId first = 1;
-  NodeId second = 2;
-
-  message Parameters {
-    transform.proto.Rigid2d first_t_second = 1;
-    double translation_weight = 2;
-    double rotation_weight = 3;
-  }
-  Parameters parameters = 3;
-}
-
-message RelativePose3D {
-  NodeId first = 1;
-  NodeId second = 2;
-
-  message Parameters {
-    transform.proto.Rigid3d first_t_second = 1;
-    double translation_weight = 2;
-    double rotation_weight = 3;
-  }
-  Parameters parameters = 3;
-}
-
-message Acceleration3D {
-  NodeId first = 1;
-  NodeId second = 2;
-  NodeId third = 3;
-  NodeId imu_calibration = 4;
-
-  message Parameters {
-    transform.proto.Vector3d delta_velocity_imu_frame = 1;
-    double first_to_second_delta_time_seconds = 2;
-    double second_to_third_delta_time_seconds = 3;
-    double scaling_factor = 4;
-  }
-  Parameters parameters = 5;
-}
-
-message Rotation3D {
-  NodeId first = 1;
-  NodeId second = 2;
-  NodeId imu_calibration = 3;
-
-  message Parameters {
-    transform.proto.Quaterniond delta_rotation_imu_frame = 1;
-    double scaling_factor = 2;
-  }
-  Parameters parameters = 4;
-}
-
-message InterpolatedRelativePose2D {
-  NodeId first_start = 1;
-  NodeId first_end = 2;
-  NodeId second = 3;
-
-  message Parameters {
-    transform.proto.Rigid3d first_t_second = 1;
-    double translation_weight = 2;
-    double rotation_weight = 3;
-    transform.proto.Quaterniond gravity_alignment_first_start = 4;
-    transform.proto.Quaterniond gravity_alignment_first_end = 5;
-     // Interpolates between first_start and first_end.
-    double interpolation_factor = 6;
-  }
-  Parameters parameters = 4;
-}
-
-message InterpolatedRelativePose3D {
-  NodeId first_start = 1;
-  NodeId first_end = 2;
-  NodeId second = 3;
-
-  message Parameters {
-    transform.proto.Rigid3d first_t_second = 1;
-    double translation_weight = 2;
-    double rotation_weight = 3;
-    // Interpolates between first_start and first_end.
-    double interpolation_factor = 4;
-  }
-  Parameters parameters = 4;
-}
-
-message CostFunction {
-  oneof type {
-    RelativePose2D relative_pose_2d = 1;
-    RelativePose3D relative_pose_3d = 2;
-    Acceleration3D acceleration_3d = 3;
-    Rotation3D rotation_3d = 4;
-    InterpolatedRelativePose2D interpolated_relative_pose_2d = 5;
-    InterpolatedRelativePose3D interpolated_relative_pose_3d = 6;
-  }
-}
diff --git a/cartographer/pose_graph/proto/loss_function.proto b/cartographer/pose_graph/proto/loss_function.proto
deleted file mode 100644
index a45e557..0000000
--- a/cartographer/pose_graph/proto/loss_function.proto
+++ /dev/null
@@ -1,30 +0,0 @@
-// Copyright 2018 The Cartographer Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-syntax = "proto3";
-
-package cartographer.pose_graph.proto;
-
-message QuadraticLoss {}
-
-message HuberLoss {
-  double scale = 1;
-}
-
-message LossFunction {
-  oneof Type {
-    QuadraticLoss quadratic_loss = 1;
-    HuberLoss huber_loss = 2;
-  }
-}
diff --git a/cartographer/pose_graph/proto/node.proto b/cartographer/pose_graph/proto/node.proto
deleted file mode 100644
index 597a95e..0000000
--- a/cartographer/pose_graph/proto/node.proto
+++ /dev/null
@@ -1,65 +0,0 @@
-// Copyright 2018 The Cartographer Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-syntax = "proto3";
-
-package cartographer.pose_graph.proto;
-
-import "cartographer/transform/proto/transform.proto";
-
-enum Parameterization {
-  NONE = 0;
-  FIX_Z = 1;
-  YAW_ONLY = 2;
-  YAW_CONSTANT = 3;
-}
-
-message Pose2D {
-  transform.proto.Vector2d translation = 1;
-  double rotation = 2;
-}
-
-message Pose3D {
-  transform.proto.Vector3d translation = 1;
-  transform.proto.Quaterniond rotation = 2;
-  Parameterization translation_parameterization = 3;
-  Parameterization rotation_parameterization = 4;
-}
-
-message ImuCalibration {
-  double gravity_constant = 1;
-  transform.proto.Quaterniond orientation = 2;
-  Parameterization orientation_parameterization = 3;
-}
-
-message NodeId {
-  string object_id = 1;
-  string group_id = 2;
-  int64 timestamp = 3;
-}
-
-message Parameters {
-  oneof type {
-    Pose2D pose_2d = 1;
-    Pose3D pose_3d = 2;
-    ImuCalibration imu_calibration = 3;
-  }
-}
-
-message Node {
-  NodeId id = 1;
-  bool constant = 2;
-  Parameters parameters = 3;
-}
-
diff --git a/cartographer/pose_graph/proto/pose_graph_data.proto b/cartographer/pose_graph/proto/pose_graph_data.proto
deleted file mode 100644
index b76966a..0000000
--- a/cartographer/pose_graph/proto/pose_graph_data.proto
+++ /dev/null
@@ -1,25 +0,0 @@
-// Copyright 2018 The Cartographer Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-syntax = "proto3";
-
-import "cartographer/pose_graph/proto/node.proto";
-import "cartographer/pose_graph/proto/constraint.proto";
-
-package cartographer.pose_graph.proto;
-
-message PoseGraphData {
-  repeated Node nodes = 1;
-  repeated Constraint constraints = 2;
-}
diff --git a/cartographer/pose_graph/proto/solver_config.proto b/cartographer/pose_graph/proto/solver_config.proto
deleted file mode 100644
index cec67cc..0000000
--- a/cartographer/pose_graph/proto/solver_config.proto
+++ /dev/null
@@ -1,14 +0,0 @@
-syntax = "proto3";
-
-import "cartographer/common/proto/ceres_solver_options.proto";
-
-package cartographer.pose_graph.proto;
-
-// Configuration for the non-linear least squares solver.
-message SolverConfig {
-  // If true, logs a summary of the optimization in every iteration.
-  bool log_solver_summary = 1;
-
-  // Options specific for the Ceres solver.
-  cartographer.common.proto.CeresSolverOptions ceres_options = 2;
-}
diff --git a/cartographer/pose_graph/solver/ceres_solver.cc b/cartographer/pose_graph/solver/ceres_solver.cc
deleted file mode 100644
index 3a7421b..0000000
--- a/cartographer/pose_graph/solver/ceres_solver.cc
+++ /dev/null
@@ -1,64 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/solver/ceres_solver.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-ceres::Problem::Options CreateCeresProblemOptions() {
-  ceres::Problem::Options problem_options;
-  problem_options.cost_function_ownership =
-      ceres::Ownership::DO_NOT_TAKE_OWNERSHIP;
-  problem_options.loss_function_ownership =
-      ceres::Ownership::DO_NOT_TAKE_OWNERSHIP;
-  problem_options.local_parameterization_ownership =
-      ceres::Ownership::DO_NOT_TAKE_OWNERSHIP;
-  return problem_options;
-}
-
-Solver::SolverStatus ToSolverStatus(
-    const ceres::TerminationType& termination_type) {
-  switch (termination_type) {
-    case (ceres::TerminationType::CONVERGENCE):
-      return Solver::SolverStatus::CONVERGENCE;
-    case (ceres::TerminationType::NO_CONVERGENCE):
-      return Solver::SolverStatus::NO_CONVERGENCE;
-    default:
-      return Solver::SolverStatus::FAILURE;
-  }
-}
-
-}  // namespace
-
-CeresSolver::CeresSolver(const ceres::Solver::Options& options)
-    : problem_options_(CreateCeresProblemOptions()), solver_options_(options) {}
-
-Solver::SolverStatus CeresSolver::Solve(PoseGraphData* data) const {
-  ceres::Problem problem(problem_options_);
-
-  for (const auto& constraint : data->constraints) {
-    constraint->AddToSolver(&data->nodes, &problem);
-  }
-
-  ceres::Solver::Summary summary;
-  ceres::Solve(solver_options_, &problem, &summary);
-  return ToSolverStatus(summary.termination_type);
-}
-
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/solver/ceres_solver.h b/cartographer/pose_graph/solver/ceres_solver.h
deleted file mode 100644
index fcaa365..0000000
--- a/cartographer/pose_graph/solver/ceres_solver.h
+++ /dev/null
@@ -1,41 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_OPTIMIZER_CERES_SOLVER_H_
-#define CARTOGRAPHER_POSE_GRAPH_OPTIMIZER_CERES_SOLVER_H_
-
-#include "cartographer/pose_graph/solver/solver.h"
-#include "ceres/problem.h"
-#include "ceres/solver.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-class CeresSolver : public Solver {
- public:
-  explicit CeresSolver(const ceres::Solver::Options& options);
-
-  SolverStatus Solve(PoseGraphData* data) const final;
-
- private:
-  const ceres::Problem::Options problem_options_;
-  const ceres::Solver::Options solver_options_;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_OPTIMIZER_CERES_SOLVER_H_
diff --git a/cartographer/pose_graph/solver/ceres_solver_test.cc b/cartographer/pose_graph/solver/ceres_solver_test.cc
deleted file mode 100644
index f86b9ae..0000000
--- a/cartographer/pose_graph/solver/ceres_solver_test.cc
+++ /dev/null
@@ -1,82 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "cartographer/pose_graph/solver/ceres_solver.h"
-
-#include "absl/memory/memory.h"
-#include "cartographer/pose_graph/constraint/relative_pose_constraint_2d.h"
-#include "cartographer/testing/test_helpers.h"
-
-namespace cartographer {
-namespace pose_graph {
-namespace {
-
-using testing::ParseProto;
-
-constexpr char kStartNode[] = R"PROTO(
-  id { object_id: "start_node" timestamp: 1 }
-  constant: false
-  parameters {
-    pose_2d {
-      translation { x: 1 y: 2 }
-      rotation: 5
-    }
-  }
-)PROTO";
-
-constexpr char kEndNode[] = R"PROTO(
-  id { object_id: "end_node" timestamp: 1 }
-  constant: false
-  parameters {
-    pose_2d {
-      translation { x: 1 y: 2 }
-      rotation: 5
-    }
-  }
-)PROTO";
-
-constexpr char kRelativePose2D[] = R"PROTO(
-  id: "constraint_1"
-  loss_function { quadratic_loss: {} }
-  cost_function {
-    relative_pose_2d {
-      first { object_id: "start_node" timestamp: 1 }
-      second { object_id: "end_node" timestamp: 1 }
-      parameters {
-        first_t_second {
-          translation { x: 1 y: 1 }
-          rotation: 0
-        }
-        translation_weight: 1
-        rotation_weight: 1
-      }
-    }
-  }
-)PROTO";
-
-TEST(CeresSolverTest, SmokeTest) {
-  PoseGraphData data;
-  AddNodeToPoseGraphData(ParseProto<proto::Node>(kStartNode), &data);
-  AddNodeToPoseGraphData(ParseProto<proto::Node>(kEndNode), &data);
-  AddConstraintToPoseGraphData(ParseProto<proto::Constraint>(kRelativePose2D),
-                               &data);
-  CeresSolver optimizer(ceres::Solver::Options{});
-  EXPECT_EQ(optimizer.Solve(&data), Solver::SolverStatus::CONVERGENCE);
-}
-
-}  // namespace
-}  // namespace pose_graph
-}  // namespace cartographer
diff --git a/cartographer/pose_graph/solver/solver.h b/cartographer/pose_graph/solver/solver.h
deleted file mode 100644
index 11bb2a1..0000000
--- a/cartographer/pose_graph/solver/solver.h
+++ /dev/null
@@ -1,45 +0,0 @@
-/*
- * Copyright 2018 The Cartographer Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef CARTOGRAPHER_POSE_GRAPH_SOLVER_SOLVER_H_
-#define CARTOGRAPHER_POSE_GRAPH_SOLVER_SOLVER_H_
-
-#include "cartographer/pose_graph/pose_graph_data.h"
-
-namespace cartographer {
-namespace pose_graph {
-
-class Solver {
- public:
-  enum class SolverStatus {
-    CONVERGENCE,
-    NO_CONVERGENCE,
-    FAILURE,
-  };
-
-  Solver() = default;
-  virtual ~Solver() = default;
-
-  Solver(const Solver&) = delete;
-  Solver& operator=(const Solver&) = delete;
-
-  virtual SolverStatus Solve(PoseGraphData* data) const = 0;
-};
-
-}  // namespace pose_graph
-}  // namespace cartographer
-
-#endif  // CARTOGRAPHER_POSE_GRAPH_SOLVER_SOLVER_H_