text: /*
   * Copyright 2016 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_LOCAL_TRAJECTORY_BUILDER_H_
  #define CARTOGRAPHER_MAPPING_2D_LOCAL_TRAJECTORY_BUILDER_H_
  
  #include <memory>
  
  #include "cartographer/common/time.h"
  #include "cartographer/mapping/pose_estimate.h"
  #include "cartographer/mapping/pose_extrapolator.h"
  #include "cartographer/mapping_2d/proto/local_trajectory_builder_options.pb.h"
  #include "cartographer/mapping_2d/scan_matching/ceres_scan_matcher.h"
  #include "cartographer/mapping_2d/scan_matching/real_time_correlative_scan_matcher.h"
  #include "cartographer/mapping_2d/submaps.h"
  #include "cartographer/mapping_3d/motion_filter.h"
  #include "cartographer/sensor/imu_data.h"
  #include "cartographer/sensor/odometry_data.h"
  #include "cartographer/sensor/range_data.h"
  #include "cartographer/sensor/voxel_filter.h"
  #include "cartographer/transform/rigid_transform.h"
  
  namespace cartographer {
  namespace mapping_2d {
  
  // Wires up the local SLAM stack (i.e. pose extrapolator, scan matching, etc.)
  // without loop closure.
  // TODO(gaschler): Add test for this class similar to the 3D test.
  class LocalTrajectoryBuilder {
   public:
    struct InsertionResult {
      std::shared_ptr<const mapping::TrajectoryNode::Data> constant_data;
      std::vector<std::shared_ptr<const Submap>> insertion_submaps;
    };
    struct MatchingResult {
      common::Time time;
      transform::Rigid3d local_pose;
      sensor::RangeData range_data_in_local;
      // 'nullptr' if dropped by the motion filter.
      std::unique_ptr<const InsertionResult> insertion_result;
    };
  
    explicit LocalTrajectoryBuilder(
        const proto::LocalTrajectoryBuilderOptions& options);
    ~LocalTrajectoryBuilder();
  
    LocalTrajectoryBuilder(const LocalTrajectoryBuilder&) = delete;
    LocalTrajectoryBuilder& operator=(const LocalTrajectoryBuilder&) = delete;
  
    // Returns 'MatchingResult' when range data accumulation completed,
    // otherwise 'nullptr'. Range data must be approximately horizontal
    // for 2D SLAM.
    std::unique_ptr<MatchingResult> AddRangeData(
        common::Time, const sensor::TimedRangeData& range_data);
    void AddImuData(const sensor::ImuData& imu_data);
    void AddOdometryData(const sensor::OdometryData& odometry_data);
  
   private:
    std::unique_ptr<MatchingResult> AddAccumulatedRangeData(
        common::Time time, const sensor::RangeData& gravity_aligned_range_data,
        const transform::Rigid3d& gravity_alignment);
    sensor::RangeData TransformToGravityAlignedFrameAndFilter(
        const transform::Rigid3f& transform_to_gravity_aligned_frame,
        const sensor::RangeData& range_data) const;
  
    std::unique_ptr<InsertionResult> InsertIntoSubmap(
        common::Time time, const sensor::RangeData& range_data_in_local,
        const sensor::RangeData& gravity_aligned_range_data,
        const transform::Rigid3d& pose_estimate,
        const Eigen::Quaterniond& gravity_alignment);
  
    // Scan matches 'gravity_aligned_range_data' and returns the observed pose,
    // or nullptr on failure.
    std::unique_ptr<transform::Rigid2d> ScanMatch(
        common::Time time, const transform::Rigid2d& pose_prediction,
        const sensor::RangeData& gravity_aligned_range_data);
  
    // Lazily constructs a PoseExtrapolator.
    void InitializeExtrapolator(common::Time time);
  
    const proto::LocalTrajectoryBuilderOptions options_;
    ActiveSubmaps active_submaps_;
  
    mapping_3d::MotionFilter motion_filter_;
    scan_matching::RealTimeCorrelativeScanMatcher
        real_time_correlative_scan_matcher_;
    scan_matching::CeresScanMatcher ceres_scan_matcher_;
  
    std::unique_ptr<mapping::PoseExtrapolator> extrapolator_;
  
    int num_accumulated_ = 0;
    transform::Rigid3f first_pose_estimate_ = transform::Rigid3f::Identity();
    sensor::RangeData accumulated_range_data_;
  };
  
  }  // namespace mapping_2d
  }  // namespace cartographer
  
  #endif  // CARTOGRAPHER_MAPPING_2D_LOCAL_TRAJECTORY_BUILDER_H_
  