[GenericPoseGraph] Add a loss function. (#1308)

cartographer/pose_graph/constraint/constraint.cc

@@ -19,10 +19,12 @@
 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;
 }
 

cartographer/pose_graph/constraint/constraint.h

@@ -17,6 +17,7 @@
 #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"
@@ -30,7 +31,9 @@ using ConstraintId = std::string;
 
 class Constraint {
  public:
-  explicit Constraint(const ConstraintId& id) : constraint_id_(id) {}
+  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;
@@ -45,8 +48,13 @@ class Constraint {
  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

cartographer/pose_graph/constraint/loss_function/loss_function.cc

@@ -0,0 +1,44 @@
+/*
+ * 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/common/make_unique.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 common::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

cartographer/pose_graph/constraint/loss_function/loss_function.h

@@ -0,0 +1,44 @@
+/*
+ * 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_

cartographer/pose_graph/constraint/loss_function/loss_function_test.cc

@@ -0,0 +1,45 @@
+/*
+ * 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/pose_graph/internal/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

cartographer/pose_graph/constraint/relative_pose_constraint_2d.cc

@@ -23,13 +23,15 @@ namespace cartographer {
 namespace pose_graph {
 
 RelativePoseConstraint2D::RelativePoseConstraint2D(
-    const ConstraintId& id, const proto::RelativePose2D& proto)
-    : Constraint(id),
+    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_(common::make_unique<RelativePoseCost2D>(proto.parameters())) {
 }
 
+// TODO(pifon): Add a test.
 void RelativePoseConstraint2D::AddToOptimizer(Nodes* nodes,
                                               ceres::Problem* problem) const {
   auto first_node = common::FindOrNull(nodes->pose_2d_nodes, first_);
@@ -60,8 +62,8 @@ void RelativePoseConstraint2D::AddToOptimizer(Nodes* nodes,
   if (second_node->constant()) {
     problem->SetParameterBlockConstant(second_pose->data());
   }
-  problem->AddResidualBlock(ceres_cost_.get(), nullptr /* loss function */,
-                            first_pose->data(), second_pose->data());
+  problem->AddResidualBlock(ceres_cost_.get(), ceres_loss(), first_pose->data(),
+                            second_pose->data());
 }
 
 proto::CostFunction RelativePoseConstraint2D::ToCostFunctionProto() const {

cartographer/pose_graph/constraint/relative_pose_constraint_2d.h

@@ -26,6 +26,7 @@ namespace pose_graph {
 class RelativePoseConstraint2D : public Constraint {
  public:
   RelativePoseConstraint2D(const ConstraintId& id,
+                           const proto::LossFunction& loss_function_proto,
                            const proto::RelativePose2D& proto);
 
   void AddToOptimizer(Nodes* nodes, ceres::Problem* problem) const final;

cartographer/pose_graph/optimizer/ceres_optimizer_test.cc

@@ -77,7 +77,8 @@ TEST(CeresOptimizerTest, SmokeTest) {
       NodeId{"end_node", common::FromUniversal(1)},
       GetPose2D(ParseProto<proto::Node>(kEndNode)));
   data.constraints.emplace_back(common::make_unique<RelativePoseConstraint2D>(
-      "constraint_1", ParseProto<proto::RelativePose2D>(kRelativePose2D)));
+      "constraint_1", ParseProto<proto::LossFunction>(R"(quadratic_loss: {})"),
+      ParseProto<proto::RelativePose2D>(kRelativePose2D)));
 
   CeresOptimizer optimizer(ceres::Solver::Options{});
   EXPECT_EQ(optimizer.Solve(&data), Optimizer::SolverStatus::CONVERGENCE);