tf info in namespace

[Jacobmo]

I am working with rtabmap in ros. I have everything working currently for a single vehicle, but am trying to launch 2 vehicles at once each running their own rtabmap. The problem i am running into is that the tf frames world->map->odom->camera_link->base_link are not in the namespace with the rest of the topics.

Is there a way to put these into the namespace so that 2 agents can run on the same ros master?

ie.
world->agent1/map->agent1/odom->agent1/camera_link->agent1/base_link.

That way I could launch 2 agents without them stepping on each other.

[matlabbe]

Hi,

You will need to change tf of your static tfs on the robot:

"robot1/base_link" -> "robot1/camera_link"
"robot2/base_link" -> "robot2/camera_link"

Make sure to launch your nodes in different namespaces. Here is an example of general launch file for rtabmap stuff:

<launch>

  <node pkg="tf" type="static_transform_publisher" name="world_to_map1"
        args="0 0 0 0 0 0 world robot1/map 100" /> 
  <node pkg="tf" type="static_transform_publisher" name="world_to_map2"
        args="0 0 0 0 0 0 world robot2/map 100" /> 

  <group ns="robot1">
    <include file="$(find rtabmap_ros)/launch/rtabmap.launch">
      <arg name="rtabmapviz"              value="false" /> 
  
      <arg name="frame_id"                value="robot1/base_link"/>
      <arg name="vo_frame_id"             value="robot1/odom"/>
      <arg name="map_frame_id"            value="robot1/map"/>
      <arg name="database_path"           value="~/.ros/robot1.db"/>

      <arg name="rgb_topic"               value="/robot1/camera/rgb/image_rect_color" />
      <arg name="depth_topic"             value="/robot1/camera/depth_registered/image_raw" />
      <arg name="camera_info_topic"       value="/robot1/camera/rgb/camera_info" />     
    </include>
  </group>

  <group ns="robot2">
    <include file="$(find rtabmap_ros)/launch/rtabmap.launch">
      <arg name="rtabmapviz"              value="false" /> 
  
      <arg name="frame_id"                value="robot2/base_link"/>
      <arg name="vo_frame_id"             value="robot2/odom"/>
      <arg name="map_frame_id"            value="robot2/map"/>
      <arg name="database_path"           value="~/.ros/robot2.db"/>

      <arg name="rgb_topic"               value="/robot2/camera/rgb/image_rect_color" />
      <arg name="depth_topic"             value="/robot2/camera/depth_registered/image_raw" />
      <arg name="camera_info_topic"       value="/robot2/camera/rgb/camera_info" />        
    </include>
  </group>

</launch>

Note also that they should not use the same database if launched from the same computer. This may not be a problem when launching on two different computers, but when launched on the same in Gazebo for example, we should explicitly change the database path.

You would get a tf tree like this:

world->robot1/map->robot1/odom->robot1/base_link->robot1/camera_link
    \->robot2/map->robot2/odom->robot2/base_link->robot2/camera_link

cheers,
Mathieu