.. 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.

=============
Configuration
=============

Note that Cartographer's ROS integration uses `tf2`_, thus all frame IDs are
expected to contain only a frame name (lower-case with underscores) and no
prefix or slashes. See `REP 105`_ for commonly used coordinate frames.

Note that topic names are given as *base* names (see `ROS Names`_) in
Cartographer's ROS integration. This means it is up to the user of the
Cartographer node to remap, or put them into a namespace.

The following are Cartographer's ROS integration top-level options, all of which
must be specified in the Lua configuration file:

map_frame
  The ROS frame ID to use for publishing submaps, the parent frame of poses,
  usually "map".

tracking_frame
  The ROS frame ID of the frame that is tracked by the SLAM algorithm. If an IMU
  is used, it should be at its position, although it might be rotated. A common
  choice is "imu_link".

published_frame
  The ROS frame ID to use as the child frame for publishing poses. For example
  "odom" if an "odom" frame is supplied by a different part of the system. In
  this case the pose of "odom" in the *map_frame* will be published. Otherwise,
  setting it to "base_link" is likely appropriate.

odom_frame
  Only used if *provide_odom_frame* is true. The frame between *published_frame*
  and *map_frame* to be used for publishing the (non-loop-closed) local SLAM
  result. Usually "odom".

provide_odom_frame
  If enabled, the local, non-loop-closed, continuous pose will be published as
  the *odom_frame* in the *map_frame*.

use_odometry
  If enabled, subscribes to `nav_msgs/Odometry`_ on the topic "odom". Odometry
  must be provided in this case, and the information will be included in SLAM.

num_laser_scans
  Number of laser scan topics to subscribe to. Subscribes to
  `sensor_msgs/LaserScan`_ on the "scan" topic for one laser scanner, or topics
  "scan_1", "scan_2", etc. for multiple laser scanners.

num_multi_echo_laser_scans
  Number of multi-echo laser scan topics to subscribe to. Subscribes to
  `sensor_msgs/MultiEchoLaserScan`_ on the "echoes" topic for one laser scanner,
  or topics "echoes_1", "echoes_2", etc. for multiple laser scanners.

num_subdivisions_per_laser_scan
  Number of point clouds to split each received (multi-echo) laser scan into.
  Subdividing a scan makes it possible to unwarp scans acquired while the
  scanners are moving. There is a corresponding trajectory builder option to
  accumulate the subdivided scans into a point cloud that will be used for scan
  matching.

num_point_clouds
  Number of point cloud topics to subscribe to. Subscribes to
  `sensor_msgs/PointCloud2`_ on the "points2" topic for one rangefinder, or
  topics "points2_1", "points2_2", etc. for multiple rangefinders.

lookup_transform_timeout_sec
  Timeout in seconds to use for looking up transforms using `tf2`_.

submap_publish_period_sec
  Interval in seconds at which to publish the submap poses, e.g. 0.3 seconds.

pose_publish_period_sec
  Interval in seconds at which to publish poses, e.g. 5e-3 for a frequency of
  200 Hz.

trajectory_publish_period_sec
  Interval in seconds at which to publish the trajectory markers, e.g. 30e-3
  for 30 milliseconds.

.. _REP 105: http://www.ros.org/reps/rep-0105.html
.. _ROS Names: http://wiki.ros.org/Names
.. _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/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
.. _tf2: http://wiki.ros.org/tf2