05. RTAB-Map Launch File

Launch File

We have the launch file to launch Gazebo and Rviz. Now, similar to what we did to create the amcl.launch in last project, we need to add the launch file for RTAB-Map!

mapping.launch

Our mapping launch file acts as the main node that interfaces with all the required parts to be able to perform SLAM with RTAB-Map . A labeled template for the mapping.launch file has been provided below. Create mapping.launch file in the launch folder.

Read through the code and the comments to understand what each part is accomplishing and why. Feel free to reach beyond this template with the documentation of RTAB-Map. You task here is to assign the correct topic to be remapped to the topics required by rtabmap .

  • scan
  • rgb/image
  • depth/image
  • rgb/camera_info

You should find the actual topics that your robot is publishing to, in the robot's urdf file. When you find the correct ones, substitute them in the <arg> tags at the beginning of this launch file. Then your mapping node could find all required information to perform RTAB-Mapping! 

<?xml version="1.0" encoding="UTF-8"?>

<launch>
  <!-- Arguments for launch file with defaults provided -->
  <arg name="database_path"     default="rtabmap.db"/>
  <arg name="rgb_topic"   default="/camera/rgb/image_raw"/>
  <arg name="depth_topic" default="/camera/depth/image_raw"/>
  <arg name="camera_info_topic" default="/camera/rgb/camera_info"/>  


  <!-- Mapping Node -->
  <group ns="rtabmap">
    <node name="rtabmap" pkg="rtabmap_ros" type="rtabmap" output="screen" args="--delete_db_on_start">

      <!-- Basic RTAB-Map Parameters -->
      <param name="database_path"       type="string" value="$(arg database_path)"/>
      <param name="frame_id"            type="string" value="base_footprint"/>
      <param name="odom_frame_id"       type="string" value="odom"/>
      <param name="subscribe_depth"     type="bool"   value="true"/>
      <param name="subscribe_scan"      type="bool"   value="true"/>

      <!-- RTAB-Map Inputs -->
      <remap from="scan" to="/scan"/>
      <remap from="rgb/image" to="$(arg rgb_topic)"/>
      <remap from="depth/image" to="$(arg depth_topic)"/>
      <remap from="rgb/camera_info" to="$(arg camera_info_topic)"/>

      <!-- RTAB-Map Output -->
      <remap from="grid_map" to="/map"/>

      <!-- Rate (Hz) at which new nodes are added to map -->
      <param name="Rtabmap/DetectionRate" type="string" value="1"/>

      <!-- 2D SLAM -->
      <param name="Reg/Force3DoF" type="string" value="true"/>

      <!-- Loop Closure Detection -->
      <!-- 0=SURF 1=SIFT 2=ORB 3=FAST/FREAK 4=FAST/BRIEF 5=GFTT/FREAK 6=GFTT/BRIEF 7=BRISK 8=GFTT/ORB 9=KAZE -->
      <param name="Kp/DetectorStrategy" type="string" value="0"/>

      <!-- Maximum visual words per image (bag-of-words) -->
      <param name="Kp/MaxFeatures" type="string" value="400"/>

      <!-- Used to extract more or less SURF features -->
      <param name="SURF/HessianThreshold" type="string" value="100"/>

      <!-- Loop Closure Constraint -->
      <!-- 0=Visual, 1=ICP (1 requires scan)-->
      <param name="Reg/Strategy" type="string" value="0"/>

      <!-- Minimum visual inliers to accept loop closure -->
      <param name="Vis/MinInliers" type="string" value="15"/>

      <!-- Set to false to avoid saving data when robot is not moving -->
      <param name="Mem/NotLinkedNodesKept" type="string" value="false"/>
    </node>
  </group>
</launch>

Next Concept