Cartographer GRPC

Cartographer has built in cloud capabilities but it is not well documented. In this post, i will give a basic server and client example.

To use Cartographer, Cloud you need cartographer_grpc_node. This node is not available with default compile settings. You can check by double tabbing after rosrun cartographer_ros.

Before recompile, you need to install GRPC dependencies. Assuming you already installed basic dependencies, you can use following scripts provided by cartographer:

~/catkin_ws/src/cartographer/scripts/install_grpc.sh
~/catkin_ws/src/cartographer/scripts/install_async_grpc.sh

Now go to your workspace and build cartographer_ros with BUILD_GRPC flag like this:

catkin build cartographer_ros -DBUILD_GRPC=ON

If successful, you should see cartographer_grpc_node:

Below you can find launch and lua files for both Cartographer Server and Client. You can also find them on my Github repository.

server.launch

<launch>
  <node name="cartographer_grpc_server" pkg="cartographer_ros"
      type="cartographer_grpc_server.sh" args="
          -configuration_directory $(find cartographer_grpc)/config
          -configuration_basename server.lua
          ">
  </node>
</launch>

server.lua

include "map_builder.lua"

MAP_BUILDER_SERVER = {
  map_builder = MAP_BUILDER,
  num_event_threads = 8,
  num_grpc_threads = 8,
  server_address = "0.0.0.0:50051",
  uplink_server_address = "",
  upload_batch_size = 100,
  enable_ssl_encryption = false,
  enable_google_auth = false,
}

MAP_BUILDER_SERVER.map_builder.use_trajectory_builder_2d = true

return MAP_BUILDER_SERVER

client.launch

<launch>
  <node name="cartographer_grpc_node" pkg="cartographer_ros"
      type="cartographer_grpc_node" args="
          -configuration_directory $(find cartographer_grpc)/config
          -configuration_basename client.lua
          -server_address localhost:50051
          -client_id CLIENT_ID
          "
      output="screen">
  </node>
</launch>

client.lua

include "map_builder.lua"
include "trajectory_builder.lua"

options = {
  map_builder = MAP_BUILDER,
  trajectory_builder = TRAJECTORY_BUILDER,
  map_frame = "map",
  tracking_frame = "base_link",
  published_frame = "base_link",
  odom_frame = "odom",
  provide_odom_frame = true,
  publish_frame_projected_to_2d = false,
  use_pose_extrapolator = true,
  use_odometry = false,
  use_nav_sat = false,
  use_landmarks = false,
  num_laser_scans = 0,
  num_multi_echo_laser_scans = 1,
  num_subdivisions_per_laser_scan = 10,
  num_point_clouds = 0,
  lookup_transform_timeout_sec = 0.2,
  submap_publish_period_sec = 0.3,
  pose_publish_period_sec = 5e-3,
  trajectory_publish_period_sec = 30e-3,
  rangefinder_sampling_ratio = 1.,
  odometry_sampling_ratio = 1.,
  fixed_frame_pose_sampling_ratio = 1.,
  imu_sampling_ratio = 1.,
  landmarks_sampling_ratio = 1.,
}

MAP_BUILDER.use_trajectory_builder_2d = true
TRAJECTORY_BUILDER_2D.num_accumulated_range_data = 10

return options

Full list of cartographer_grpc_node parameters and their descriptions can be found at :

~/catkin_ws/src/cartographer_ros/cartographer_ros/cartographer_ros/cartographer_grpc/node_grpc_main.cc

If everything went correctly, you can use Cartographer Cloud now. To start server and client, run respective launch files. After client registered to server, server output should look like this:

Notes

1. Server address is the IP address of the computer which cartographer_grpc_server.sh is working on. If server and client is working on the same computer, you can leave it as localhost
2. Unless upload_load_state_file param is set to true, pbstream file pointed with load_frozen_state is relative to the servers file system. This means pbstream file should be located at server side.
3. Last pbstream file uploaded to server overrides current submaps. For example, if you are mapping with a client and later you start another client with localization mode, all submaps in the server will be replaced with the ones in new pbstream file.
4. cartographer_grpc_server.sh does not publish submaps therefore if clients are on different computers you should use something else (ROS Network, etc.) to see the map.
5. client_id is a string and should be unique for every client.