Add TSDF2D Grid (#1209)

- Adds TSDF2D Grid
- Adds tests for TSDF2D Grid
- Introduces Grid2D::GrowLimits(...) for multiple grids to reduce code duplication between TSDF2D and Grid2D

cartographer/mapping/2d/grid_2d.cc

@@ -114,6 +114,13 @@ void Grid2D::ComputeCroppedLimits(Eigen::Array2i* const offset,
 // these coordinates going forward. This method must be called immediately
 // after 'FinishUpdate', before any calls to 'ApplyLookupTable'.
 void Grid2D::GrowLimits(const Eigen::Vector2f& point) {
+  GrowLimits(point, {mutable_correspondence_cost_cells()},
+             {kUnknownCorrespondenceValue});
+}
+
+void Grid2D::GrowLimits(const Eigen::Vector2f& point,
+                        const std::vector<std::vector<uint16>*>& grids,
+                        const std::vector<uint16>& grids_unknown_cell_values) {
   CHECK(update_indices_.empty());
   while (!limits_.Contains(limits_.GetCellIndex(point))) {
     const int x_offset = limits_.cell_limits().num_x_cells / 2;
@@ -128,15 +135,18 @@ void Grid2D::GrowLimits(const Eigen::Vector2f& point) {
     const int offset = x_offset + stride * y_offset;
     const int new_size = new_limits.cell_limits().num_x_cells *
                          new_limits.cell_limits().num_y_cells;
-    std::vector<uint16> new_cells(new_size, kUnknownCorrespondenceValue);
+
+    for (size_t grid_index = 0; grid_index < grids.size(); ++grid_index) {
+      std::vector<uint16> new_cells(new_size,
+                                    grids_unknown_cell_values[grid_index]);
       for (int i = 0; i < limits_.cell_limits().num_y_cells; ++i) {
         for (int j = 0; j < limits_.cell_limits().num_x_cells; ++j) {
           new_cells[offset + j + i * stride] =
-            correspondence_cost_cells_[j +
+              (*grids[grid_index])[j + i * limits_.cell_limits().num_x_cells];
-                                       i * limits_.cell_limits().num_x_cells];
         }
       }
-    correspondence_cost_cells_ = new_cells;
+      *grids[grid_index] = new_cells;
+    }
     limits_ = new_limits;
     if (!known_cells_box_.isEmpty()) {
       known_cells_box_.translate(Eigen::Vector2i(x_offset, y_offset));
@@ -147,10 +157,8 @@ void Grid2D::GrowLimits(const Eigen::Vector2f& point) {
 proto::Grid2D Grid2D::ToProto() const {
   proto::Grid2D result;
   *result.mutable_limits() = mapping::ToProto(limits_);
-  result.mutable_cells()->Reserve(correspondence_cost_cells_.size());
+  *result.mutable_cells() = {correspondence_cost_cells_.begin(),
-  for (const auto& cell : correspondence_cost_cells_) {
+                             correspondence_cost_cells_.end()};
-    result.mutable_cells()->Add(cell);
-  }
   CHECK(update_indices().empty()) << "Serializing a grid during an update is "
                                      "not supported. Finish the update first.";
   if (!known_cells_box().isEmpty()) {

cartographer/mapping/2d/grid_2d.h

@@ -33,7 +33,7 @@ proto::GridOptions2D CreateGridOptions2D(
 
 class Grid2D : public GridInterface {
  public:
-  explicit Grid2D(const MapLimits& limits, float min_correspondence_cost,
+  Grid2D(const MapLimits& limits, float min_correspondence_cost,
          float max_correspondence_cost);
   explicit Grid2D(const proto::Grid2D& proto);
 
@@ -73,6 +73,10 @@ class Grid2D : public GridInterface {
       transform::Rigid3d local_pose) const = 0;
 
  protected:
+  void GrowLimits(const Eigen::Vector2f& point,
+                  const std::vector<std::vector<uint16>*>& grids,
+                  const std::vector<uint16>& grids_unknown_cell_values);
+
   const std::vector<uint16>& correspondence_cost_cells() const {
     return correspondence_cost_cells_;
   }

cartographer/mapping/2d/tsdf_2d.cc

@@ -0,0 +1,173 @@
+/*
+ * 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/mapping/2d/tsdf_2d.h"
+
+#include <limits>
+
+#include "cartographer/common/make_unique.h"
+
+namespace cartographer {
+namespace mapping {
+
+TSDF2D::TSDF2D(const MapLimits& limits, float truncation_distance,
+               float max_weight)
+    : Grid2D(limits, -truncation_distance, truncation_distance),
+      value_converter_(common::make_unique<TSDValueConverter>(
+          truncation_distance, max_weight)),
+      weight_cells_(
+          limits.cell_limits().num_x_cells * limits.cell_limits().num_y_cells,
+          value_converter_->getUnknownWeightValue()) {}
+
+TSDF2D::TSDF2D(const proto::Grid2D& proto) : Grid2D(proto) {
+  CHECK(proto.has_tsdf_2d());
+  value_converter_ = common::make_unique<TSDValueConverter>(
+      proto.tsdf_2d().truncation_distance(), proto.tsdf_2d().max_weight());
+  weight_cells_.reserve(proto.tsdf_2d().weight_cells_size());
+  for (const auto& cell : proto.tsdf_2d().weight_cells()) {
+    CHECK_LE(cell, std::numeric_limits<uint16>::max());
+    weight_cells_.push_back(cell);
+  }
+}
+
+void TSDF2D::SetCell(const Eigen::Array2i& cell_index, float tsd,
+                     float weight) {
+  const int flat_index = ToFlatIndex(cell_index);
+  uint16* tsdf_cell = &(*mutable_correspondence_cost_cells())[flat_index];
+  uint16* weight_cell = &weight_cells_[flat_index];
+  if (*tsdf_cell >= value_converter_->getUpdateMarker()) {
+    return;
+  }
+  mutable_update_indices()->push_back(flat_index);
+  mutable_known_cells_box()->extend(cell_index.matrix());
+  *tsdf_cell =
+      value_converter_->TSDToValue(tsd) + value_converter_->getUpdateMarker();
+  *weight_cell = value_converter_->WeightToValue(weight);
+  return;
+}
+
+float TSDF2D::GetTSD(const Eigen::Array2i& cell_index) const {
+  if (limits().Contains(cell_index)) {
+    return value_converter_->ValueToTSD(
+        correspondence_cost_cells()[ToFlatIndex(cell_index)]);
+  }
+  return value_converter_->getMinTSD();
+}
+
+float TSDF2D::GetWeight(const Eigen::Array2i& cell_index) const {
+  if (limits().Contains(cell_index)) {
+    return value_converter_->ValueToWeight(
+        weight_cells_[ToFlatIndex(cell_index)]);
+  }
+  return value_converter_->getMinWeight();
+}
+
+std::pair<float, float> TSDF2D::GetTSDAndWeight(
+    const Eigen::Array2i& cell_index) const {
+  if (limits().Contains(cell_index)) {
+    int flat_index = ToFlatIndex(cell_index);
+    return std::make_pair(
+        value_converter_->ValueToTSD(correspondence_cost_cells()[flat_index]),
+        value_converter_->ValueToWeight(weight_cells_[flat_index]));
+  }
+  return std::make_pair(value_converter_->getMinTSD(),
+                        value_converter_->getMinWeight());
+}
+
+void TSDF2D::GrowLimits(const Eigen::Vector2f& point) {
+  Grid2D::GrowLimits(point,
+                     {mutable_correspondence_cost_cells(), &weight_cells_},
+                     {value_converter_->getUnknownTSDValue(),
+                      value_converter_->getUnknownWeightValue()});
+}
+
+proto::Grid2D TSDF2D::ToProto() const {
+  proto::Grid2D result;
+  result = Grid2D::ToProto();
+  *result.mutable_tsdf_2d()->mutable_weight_cells() = {weight_cells_.begin(),
+                                                       weight_cells_.end()};
+  result.mutable_tsdf_2d()->set_truncation_distance(
+      value_converter_->getMaxTSD());
+  result.mutable_tsdf_2d()->set_max_weight(value_converter_->getMaxWeight());
+  return result;
+}
+
+std::unique_ptr<Grid2D> TSDF2D::ComputeCroppedGrid() const {
+  Eigen::Array2i offset;
+  CellLimits cell_limits;
+  ComputeCroppedLimits(&offset, &cell_limits);
+  const double resolution = limits().resolution();
+  const Eigen::Vector2d max =
+      limits().max() - resolution * Eigen::Vector2d(offset.y(), offset.x());
+  std::unique_ptr<TSDF2D> cropped_grid = common::make_unique<TSDF2D>(
+      MapLimits(resolution, max, cell_limits), value_converter_->getMaxTSD(),
+      value_converter_->getMaxWeight());
+  for (const Eigen::Array2i& xy_index : XYIndexRangeIterator(cell_limits)) {
+    if (!IsKnown(xy_index + offset)) continue;
+    cropped_grid->SetCell(xy_index, GetTSD(xy_index + offset),
+                          GetWeight(xy_index + offset));
+  }
+  return std::move(cropped_grid);
+}
+
+bool TSDF2D::DrawToSubmapTexture(
+    proto::SubmapQuery::Response::SubmapTexture* const texture,
+    transform::Rigid3d local_pose) const {
+  Eigen::Array2i offset;
+  CellLimits cell_limits;
+  ComputeCroppedLimits(&offset, &cell_limits);
+
+  std::string cells;
+  for (const Eigen::Array2i& xy_index : XYIndexRangeIterator(cell_limits)) {
+    if (!IsKnown(xy_index + offset)) {
+      cells.push_back(0);  // value
+      cells.push_back(0);  // alpha
+    }
+    // We would like to add 'delta' but this is not possible using a value and
+    // alpha. We use premultiplied alpha, so when 'delta' is positive we can
+    // add it by setting 'alpha' to zero. If it is negative, we set 'value' to
+    // zero, and use 'alpha' to subtract. This is only correct when the pixel
+    // is currently white, so walls will look too gray. This should be hard to
+    // detect visually for the user, though.
+    float normalized_tsdf = std::abs(GetTSD(xy_index + offset));
+    normalized_tsdf =
+        std::pow(normalized_tsdf / value_converter_->getMaxTSD(), 0.5f);
+    float normalized_weight =
+        GetWeight(xy_index + offset) / value_converter_->getMaxWeight();
+    const int delta = static_cast<int>(
+        std::round(normalized_weight * (normalized_tsdf * 255. - 128.)));
+    const uint8 alpha = delta > 0 ? 0 : -delta;
+    const uint8 value = delta > 0 ? delta : 0;
+    cells.push_back(value);
+    cells.push_back((value || alpha) ? alpha : 1);
+  }
+
+  common::FastGzipString(cells, texture->mutable_cells());
+  texture->set_width(cell_limits.num_x_cells);
+  texture->set_height(cell_limits.num_y_cells);
+  const double resolution = limits().resolution();
+  texture->set_resolution(resolution);
+  const double max_x = limits().max().x() - resolution * offset.y();
+  const double max_y = limits().max().y() - resolution * offset.x();
+  *texture->mutable_slice_pose() = transform::ToProto(
+      local_pose.inverse() *
+      transform::Rigid3d::Translation(Eigen::Vector3d(max_x, max_y, 0.)));
+
+  return true;
+}
+
+}  // namespace mapping
+}  // namespace cartographer

cartographer/mapping/2d/tsdf_2d.h

@@ -0,0 +1,58 @@
+/*
+ * 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_MAPPING_2D_TSDF_2D_H_
+#define CARTOGRAPHER_MAPPING_2D_TSDF_2D_H_
+
+#include <vector>
+
+#include "cartographer/common/port.h"
+#include "cartographer/mapping/2d/grid_2d.h"
+#include "cartographer/mapping/2d/map_limits.h"
+#include "cartographer/mapping/2d/xy_index.h"
+#include "cartographer/mapping/internal/tsd_value_converter.h"
+namespace cartographer {
+namespace mapping {
+
+// Represents a 2D grid of truncated signed distances and weights.
+class TSDF2D : public Grid2D {
+ public:
+  TSDF2D(const MapLimits& limits, float truncation_distance, float max_weight);
+  explicit TSDF2D(const proto::Grid2D& proto);
+
+  void SetCell(const Eigen::Array2i& cell_index, const float tsd,
+               const float weight);
+  float GetTSD(const Eigen::Array2i& cell_index) const;
+  float GetWeight(const Eigen::Array2i& cell_index) const;
+  std::pair<float, float> GetTSDAndWeight(
+      const Eigen::Array2i& cell_index) const;
+
+  virtual void GrowLimits(const Eigen::Vector2f& point) override;
+  proto::Grid2D ToProto() const;
+  virtual std::unique_ptr<Grid2D> ComputeCroppedGrid() const override;
+  virtual bool DrawToSubmapTexture(
+      proto::SubmapQuery::Response::SubmapTexture* const texture,
+      transform::Rigid3d local_pose) const override;
+
+ private:
+  std::unique_ptr<TSDValueConverter> value_converter_;
+  std::vector<uint16> weight_cells_;  // Highest bit is update marker.
+};
+
+}  // namespace mapping
+}  // namespace cartographer
+
+#endif  // CARTOGRAPHER_MAPPING_2D_TSDF_2D_H_

cartographer/mapping/2d/tsdf_2d_test.cc

@@ -0,0 +1,155 @@
+/*
+ * 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/mapping/2d/tsdf_2d.h"
+
+#include <random>
+
+#include "gtest/gtest.h"
+
+namespace cartographer {
+namespace mapping {
+namespace {
+
+using Eigen::Array2i;
+using Eigen::Vector2f;
+
+TEST(TSDF2DTest, ProtoConstructor) {
+  proto::Grid2D proto;
+  const MapLimits limits(1., {2., 3.}, CellLimits(4., 5.));
+  *proto.mutable_limits() = ToProto(limits);
+  proto.mutable_tsdf_2d()->set_max_weight(10.0);
+  proto.mutable_tsdf_2d()->set_truncation_distance(1.0);
+  for (int i = 6; i < 12; ++i) {
+    proto.mutable_cells()->Add(static_cast<uint16>(i));
+    proto.mutable_tsdf_2d()->mutable_weight_cells()->Add(
+        static_cast<uint16>(i));
+  }
+  proto.mutable_known_cells_box()->set_max_x(19);
+  proto.mutable_known_cells_box()->set_max_y(20);
+  proto.mutable_known_cells_box()->set_min_x(21);
+  proto.mutable_known_cells_box()->set_min_y(22);
+  proto.set_max_correspondence_cost(1.0);
+  proto.set_min_correspondence_cost(-1.0);
+
+  TSDF2D grid(proto);
+  EXPECT_EQ(proto.limits().DebugString(), ToProto(grid.limits()).DebugString());
+}
+
+TEST(TSDF2DTest, ToProto) {
+  TSDF2D tsdf(MapLimits(1., Eigen::Vector2d(1., 1.), CellLimits(2, 2)), 1.0f,
+              10.0f);
+
+  const auto proto = tsdf.ToProto();
+  EXPECT_EQ(ToProto(tsdf.limits()).DebugString(), proto.limits().DebugString());
+}
+
+TEST(TSDF2DTest, GetCellIndex) {
+  TSDF2D tsdf(MapLimits(2., Eigen::Vector2d(8., 14.), CellLimits(14, 8)), 1.f,
+              10.f);
+
+  const MapLimits& limits = tsdf.limits();
+  const CellLimits& cell_limits = limits.cell_limits();
+  ASSERT_EQ(14, cell_limits.num_x_cells);
+  ASSERT_EQ(8, cell_limits.num_y_cells);
+  EXPECT_TRUE(
+      (Array2i(0, 0) == limits.GetCellIndex(Vector2f(7.f, 13.f))).all());
+  EXPECT_TRUE(
+      (Array2i(13, 0) == limits.GetCellIndex(Vector2f(7.f, -13.f))).all());
+  EXPECT_TRUE(
+      (Array2i(0, 7) == limits.GetCellIndex(Vector2f(-7.f, 13.f))).all());
+  EXPECT_TRUE(
+      (Array2i(13, 7) == limits.GetCellIndex(Vector2f(-7.f, -13.f))).all());
+
+  // Check around the origin.
+  EXPECT_TRUE(
+      (Array2i(6, 3) == limits.GetCellIndex(Vector2f(0.5f, 0.5f))).all());
+  EXPECT_TRUE(
+      (Array2i(6, 3) == limits.GetCellIndex(Vector2f(1.5f, 1.5f))).all());
+  EXPECT_TRUE(
+      (Array2i(7, 3) == limits.GetCellIndex(Vector2f(0.5f, -0.5f))).all());
+  EXPECT_TRUE(
+      (Array2i(6, 4) == limits.GetCellIndex(Vector2f(-0.5f, 0.5f))).all());
+  EXPECT_TRUE(
+      (Array2i(7, 4) == limits.GetCellIndex(Vector2f(-0.5f, -0.5f))).all());
+}
+
+TEST(TSDF2DTest, WriteRead) {
+  const float truncation_distance = 1.f;
+  const float max_weight = 10.f;
+  TSDF2D tsdf(MapLimits(1., Eigen::Vector2d(1., 2.), CellLimits(2, 2)),
+              truncation_distance, max_weight);
+
+  const MapLimits& limits = tsdf.limits();
+  EXPECT_EQ(1., limits.max().x());
+  EXPECT_EQ(2., limits.max().y());
+
+  const CellLimits& cell_limits = limits.cell_limits();
+  ASSERT_EQ(2, cell_limits.num_x_cells);
+  ASSERT_EQ(2, cell_limits.num_y_cells);
+
+  std::mt19937 rng(42);
+  std::uniform_real_distribution<float> tsd_distribution(-truncation_distance,
+                                                         truncation_distance);
+  std::uniform_real_distribution<float> weight_distribution(0.f, max_weight);
+  for (size_t i = 0; i < 1; ++i) {
+    const float tsd = tsd_distribution(rng);
+    const float weight = weight_distribution(rng);
+    tsdf.SetCell(limits.GetCellIndex(Vector2f(-0.5f, 0.5f)), tsd, weight);
+    EXPECT_NEAR(
+        tsdf.GetTSDAndWeight(limits.GetCellIndex(Vector2f(-0.5f, 0.5f))).first,
+        tsd, 2.f * truncation_distance / 32768.f);
+    EXPECT_NEAR(
+        tsdf.GetTSDAndWeight(limits.GetCellIndex(Vector2f(-0.5f, 0.5f))).second,
+        weight, max_weight / 32768.f);
+    EXPECT_NEAR(tsdf.GetTSD(limits.GetCellIndex(Vector2f(-0.5f, 0.5f))), tsd,
+                2.f * truncation_distance / 32768.f);
+    EXPECT_NEAR(tsdf.GetWeight(limits.GetCellIndex(Vector2f(-0.5f, 0.5f))),
+                weight, max_weight / 32768.f);
+  }
+  for (const Array2i& xy_index : {limits.GetCellIndex(Vector2f(-0.5f, 1.5f)),
+                                  limits.GetCellIndex(Vector2f(0.5f, 0.5f)),
+                                  limits.GetCellIndex(Vector2f(0.5f, 1.5f))}) {
+    EXPECT_TRUE(limits.Contains(xy_index));
+    EXPECT_FALSE(tsdf.IsKnown(xy_index));
+  }
+}
+
+TEST(TSDF2DTest, CorrectCropping) {
+  // Create a TSDF with random values.
+  const float truncation_distance = 1.f;
+  const float max_weight = 10.f;
+  std::mt19937 rng(42);
+  std::uniform_real_distribution<float> tsdf_distribution(-truncation_distance,
+                                                          truncation_distance);
+  std::uniform_real_distribution<float> weight_distribution(0.f, max_weight);
+  TSDF2D tsdf(MapLimits(0.05, Eigen::Vector2d(10., 10.), CellLimits(400, 400)),
+              truncation_distance, max_weight);
+  for (const Array2i& xy_index :
+       XYIndexRangeIterator(Array2i(100, 100), Array2i(299, 299))) {
+    tsdf.SetCell(xy_index, tsdf_distribution(rng), weight_distribution(rng));
+  }
+  Array2i offset;
+  CellLimits limits;
+  tsdf.ComputeCroppedLimits(&offset, &limits);
+  EXPECT_TRUE((offset == Array2i(100, 100)).all());
+  EXPECT_EQ(limits.num_x_cells, 200);
+  EXPECT_EQ(limits.num_y_cells, 200);
+}
+
+}  // namespace
+}  // namespace mapping
+}  // namespace cartographer

cartographer/mapping/proto/2d/grid_2d.proto

@@ -18,6 +18,7 @@ package cartographer.mapping.proto;
 
 import "cartographer/mapping/proto/2d/map_limits.proto";
 import "cartographer/mapping/proto/2d/probability_grid.proto";
+import "cartographer/mapping/proto/2d/tsdf_2d.proto";
 
 message Grid2D {
   message CellBox {
@@ -34,6 +35,7 @@ message Grid2D {
   CellBox known_cells_box = 3;
   oneof grid {
     ProbabilityGrid probability_grid_2d = 4;
+    TSDF2D tsdf_2d = 5;
   }
   float min_correspondence_cost = 6;
   float max_correspondence_cost = 7;

cartographer/mapping/proto/2d/tsdf_2d.proto

@@ -0,0 +1,23 @@
+// 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.mapping.proto;
+
+message TSDF2D {
+  float truncation_distance = 1;
+  float max_weight = 2;
+  repeated int32 weight_cells = 3;
+}