.. 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. ======= ROS API ======= Cartographer Node ================= The `cartographer_node`_ is the SLAM node used for online, real-time SLAM. .. _cartographer_node: https://github.com/googlecartographer/cartographer_ros/blob/master/cartographer_ros/cartographer_ros/node_main.cc Command-line Flags ------------------ Call the node with the ``--help`` flag to see all available options. Subscribed Topics ----------------- The following range data topics are mutually exclusive. At least one source of range data is required. scan (`sensor_msgs/LaserScan`_) Supported in 2D and 3D (e.g. using an axially rotating planar laser scanner). If *num_laser_scans* is set to 1 in the :doc:`configuration`, this topic will be used as input for SLAM. If *num_laser_scans* is greater than 1, multiple numbered scan topics (i.e. scan_1, scan_2, scan_3, ... up to and including *num_laser_scans*) will be used as inputs for SLAM. echoes (`sensor_msgs/MultiEchoLaserScan`_) Supported in 2D and 3D (e.g. using an axially rotating planar laser scanner). If *num_multi_echo_laser_scans* is set to 1 in the :doc:`configuration`, this topic will be used as input for SLAM. Only the first echo is used. If *num_multi_echo_laser_scans* is greater than 1, multiple numbered echoes topics (i.e. echoes_1, echoes_2, echoes_3, ... up to and including *num_multi_echo_laser_scans*) will be used as inputs for SLAM. points2 (`sensor_msgs/PointCloud2`_) If *num_point_clouds* is set to 1 in the :doc:`configuration`, this topic will be used as input for SLAM. If *num_point_clouds* is greater than 1, multiple numbered points2 topics (i.e. points2_1, points2_2, points2_3, ... up to and including *num_point_clouds*) will be used as inputs for SLAM. The following additional sensor data topics may also be provided: imu (`sensor_msgs/Imu`_) Supported in 2D (optional) and 3D (required). This topic will be used as input for SLAM. odom (`nav_msgs/Odometry`_) Supported in 2D (optional) and 3D (optional). If *use_odometry* is enabled in the :doc:`configuration`, this topic will be used as input for SLAM. .. TODO: add NavSatFix? Landmarks? Published Topics ---------------- scan_matched_points2 (`sensor_msgs/PointCloud2`_) Point cloud as it was used for the purpose of scan-to-submap matching. This cloud may be both filtered and projected depending on the :doc:`configuration`. submap_list (`cartographer_ros_msgs/SubmapList`_) List of all submaps, including the pose and latest version number of each submap, across all trajectories. Services -------- All services responses include also a ``StatusResponse`` that comprises a ``code`` and a ``message`` field. For consistency, the integer ``code`` is equivalent to the status codes used in the `gRPC`_ API. .. _gRPC: https://developers.google.com/maps-booking/reference/grpc-api/status_codes submap_query (`cartographer_ros_msgs/SubmapQuery`_) Fetches the requested submap. start_trajectory (`cartographer_ros_msgs/StartTrajectory`_) Starts another trajectory by specifying its sensor topics and trajectory options as an binary-encoded proto. Returns an assigned trajectory ID. The ``start_trajectory`` executable provides a convenient wrapper to use this service. finish_trajectory (`cartographer_ros_msgs/FinishTrajectory`_) Finishes the given `trajectory_id`'s trajectory by running a final optimization. write_state (`cartographer_ros_msgs/WriteState`_) Writes the current internal state to disk into `filename`. The file will usually end up in `~/.ros` or `ROS_HOME` if it is set. This file can be used as input to the `assets_writer_main` to generate assets like probability grids, X-Rays or PLY files. get_trajectory_states (`cartographer_ros_msgs/GetTrajectoryStates`_) Returns the IDs and the states of the trajectories. For example, this can be useful to observe the state of Cartographer from a separate node. read_metrics (`cartographer_ros_msgs/ReadMetrics`_) Returns the latest values of all internal metrics of Cartographer. The collection of runtime metrics is optional and has to be activated with the ``--collect_metrics`` command line flag in the node. Required tf Transforms ---------------------- Transforms from all incoming sensor data frames to the :doc:`configured ` *tracking_frame* and *published_frame* must be available. Typically, these are published periodically by a `robot_state_publisher` or a `static_transform_publisher`. Provided tf Transforms ---------------------- The transformation between the :doc:`configured ` *map_frame* and *published_frame* is always provided. If *provide_odom_frame* is enabled in the :doc:`configuration`, a continuous (i.e. unaffected by loop closure) transform between the :doc:`configured ` *odom_frame* and *published_frame* will be provided. .. _robot_state_publisher: http://wiki.ros.org/robot_state_publisher .. _static_transform_publisher: http://wiki.ros.org/tf#static_transform_publisher .. _cartographer_ros_msgs/FinishTrajectory: https://github.com/googlecartographer/cartographer_ros/blob/master/cartographer_ros_msgs/srv/FinishTrajectory.srv .. _cartographer_ros_msgs/SubmapList: https://github.com/googlecartographer/cartographer_ros/blob/master/cartographer_ros_msgs/msg/SubmapList.msg .. _cartographer_ros_msgs/SubmapQuery: https://github.com/googlecartographer/cartographer_ros/blob/master/cartographer_ros_msgs/srv/SubmapQuery.srv .. _cartographer_ros_msgs/StartTrajectory: https://github.com/googlecartographer/cartographer_ros/blob/master/cartographer_ros_msgs/srv/StartTrajectory.srv .. _cartographer_ros_msgs/WriteState: https://github.com/googlecartographer/cartographer_ros/blob/master/cartographer_ros_msgs/srv/WriteState.srv .. _cartographer_ros_msgs/GetTrajectoryStates: https://github.com/googlecartographer/cartographer_ros/blob/master/cartographer_ros_msgs/srv/GetTrajectoryStates.srv .. _cartographer_ros_msgs/ReadMetrics: https://github.com/googlecartographer/cartographer_ros/blob/master/cartographer_ros_msgs/srv/ReadMetrics.srv .. _nav_msgs/OccupancyGrid: http://docs.ros.org/api/nav_msgs/html/msg/OccupancyGrid.html .. _nav_msgs/Odometry: http://docs.ros.org/api/nav_msgs/html/msg/Odometry.html .. _sensor_msgs/Imu: http://docs.ros.org/api/sensor_msgs/html/msg/Imu.html .. _sensor_msgs/LaserScan: http://docs.ros.org/api/sensor_msgs/html/msg/LaserScan.html .. _sensor_msgs/MultiEchoLaserScan: http://docs.ros.org/api/sensor_msgs/html/msg/MultiEchoLaserScan.html .. _sensor_msgs/PointCloud2: http://docs.ros.org/api/sensor_msgs/html/msg/PointCloud2.html Offline Node ============ The `offline_node`_ is the fastest way of SLAMing a bag of sensor data. It does not listen on any topics, instead it reads TF and sensor data out of a set of bags provided on the commandline. It also publishes a clock with the advancing sensor data, i.e. replaces ``rosbag play``. In all other regards, it behaves like the ``cartographer_node``. Each bag will become a separate trajectory in the final state. Once it is done processing all data, it writes out the final Cartographer state and exits. .. _offline_node: https://github.com/googlecartographer/cartographer_ros/blob/master/cartographer_ros/cartographer_ros/offline_node_main.cc Occupancy grid Node =================== The `occupancy_grid_node`_ listens to the submaps published by SLAM, builds an ROS occupancy_grid out of them and publishes it. This tool is useful to keep old nodes that require a single monolithic map to work happy until new nav stacks can deal with Cartographer's submaps directly. Generating the map is expensive and slow, so map updates are in the order of seconds. You can can selectively include/exclude submaps from frozen (static) or active trajectories with a command line option. Call the node with the ``--help`` flag to see these options. .. _occupancy_grid_node: https://github.com/googlecartographer/cartographer_ros/blob/master/cartographer_ros/cartographer_ros/occupancy_grid_node_main.cc Subscribed Topics ----------------- It subscribes to Cartographer's ``submap_list`` topic only. Published Topics ---------------- map (`nav_msgs/OccupancyGrid`_) If subscribed to, the node will continuously compute and publish the map. The time between updates will increase with the size of the map. For faster updates, use the submaps APIs. Pbstream Map Publisher Node =========================== The `pbstream_map_publisher`_ is a simple node that creates a static occupancy grid out of a serialized Cartographer state (pbstream format). It is an efficient alternative to the occupancy grid node if live updates are not important. .. _pbstream_map_publisher: https://github.com/googlecartographer/cartographer_ros/blob/master/cartographer_ros/cartographer_ros/pbstream_map_publisher_main.cc Subscribed Topics ----------------- None. Published Topics ---------------- map (`nav_msgs/OccupancyGrid`_) The published occupancy grid topic is latched.