rtabmap_ros won't subscribe to 3D point cloud from velodyne.

edit

Thx for the update, I can see the problem. rtabmap_ros cannot subscribe to scan topics when using stereo topics (for synchronization issue). We should use rgb/depth interface instead.

To make sure we are using exactly synchronized camera topics while we are subscribing to a scan topic (approximately synchronized), we need to use the rtabmap_ros/rgbd_sync nodelet prior to rtabmap node. Here is an example using direclty rgb/depth images from zed_wrapper (zed_rgbd_mode:=true) or using stereo_image_proc to generate depth image from left/right images of zed_wrapper (zed_rgbd_mode:=false). You will need latest version of rtabmap.launch and this is tested with this version of zed_wrapper (we should apply an optical rotation for the stereo mode).

<launch>

   <arg name="zed_rgbd_mode"        default="false"/>
   <arg name="subscribe_scan_cloud" default="true"/>
   <arg name="frame_id"             default="base_link"/>
   <arg name="rtabmap_args"         default="--delete_db_on_start"/>

   <arg name="pi/2" value="1.5707963267948966" />
   <arg name="optical_rotate" value="0 0 0 -$(arg pi/2) 0 -$(arg pi/2)" />
   <node     if="$(arg zed_rgbd_mode)" pkg="tf" type="static_transform_publisher" name="camera_base_link" 
       args="0 0 0 0 0 0 $(arg frame_id) zed_center 100" /> 
   <node unless="$(arg zed_rgbd_mode)" pkg="tf" type="static_transform_publisher" name="camera_base_link" 
       args="$(arg optical_rotate) $(arg frame_id) zed_center 100" /> 

   <group ns="/zed" >

      <include file="$(find zed_wrapper)/launch/zed_camera.launch">
         <arg name="publish_tf" value="false"/>
      </include> 

      <node unless="$(arg zed_rgbd_mode)" pkg="stereo_image_proc" type="stereo_image_proc" name="stereo_image_proc">
         <remap from="left/image_raw"    to="left/image_rect_color"/>
         <remap from="left/camera_info"  to="left/camera_info"/>
         <remap from="right/image_raw"   to="right/image_rect_color"/>
         <remap from="right/camera_info" to="right/camera_info"/>
         <param name="disparity_range" value="200"/>
      </node>

      <node pkg="nodelet" type="nodelet" name="camera_nodelet_manager"  args="manager"/>
      <node unless="$(arg zed_rgbd_mode)" pkg="nodelet" type="nodelet" name="disparity2depth" 
         args="load rtabmap_ros/disparity_to_depth camera_nodelet_manager"/>

      <node     if="$(arg zed_rgbd_mode)" pkg="nodelet" type="nodelet" name="rgbd_sync" args="load rtabmap_ros/rgbd_sync camera_nodelet_manager">
         <remap from="rgb/image"       to="rgb/image_rect_color"/>
         <remap from="depth/image"     to="depth/depth_registered"/>
         <remap from="rgb/camera_info" to="rgb/camera_info"/>
         <param name="approx_sync"     value="false"/>
      </node>
      <node unless="$(arg zed_rgbd_mode)" pkg="nodelet" type="nodelet" name="rgbd_sync" args="load rtabmap_ros/rgbd_sync camera_nodelet_manager">
         <remap from="rgb/image"       to="left/image_rect_color"/>
         <remap from="depth/image"     to="depth"/>
         <remap from="rgb/camera_info" to="left/camera_info"/>
         <param name="approx_sync"     value="false"/>
      </node>
   </group>

   <include file="$(find rtabmap_ros)/launch/rtabmap.launch">
      <arg name="frame_id"                value="$(arg frame_id)"/>
      <arg name="subscribe_rgbd"          value="true"/>
      <arg name="subscribe_scan_cloud"    value="$(arg subscribe_scan_cloud)" />
      <arg name="approx_sync"             value="true"/>
      <arg name="rgbd_topic"              value="/zed/rgbd_image" />
      <arg name="scan_cloud_topic"        value="/velodyne_points" />
      <arg name="rtabmap_args"            value="$(arg rtabmap_args)"/>

      <arg name="rtabmapviz"              value="false"/>
      <arg name="rviz"                    value="true"/>
   </include>

</launch>

Another optimization would be to use the zed nodelet inside the camera nodelet manager to avoid some serialization/deserialization.

cheers