Nodelet topic connection problem

edit

Is stereo_nodelet exist? If not, you have two choices: you create a nodelet manager for the two nodelets or create them as standalone nodelets:

<node pkg="nodelet" type="nodelet" name="nodelet_manager"  args="manager"/>

<!-- Generate a point cloud from the disparity image -->
<node pkg="nodelet" type="nodelet" name="disparity2cloud" args="load rtabmap_ros/point_cloud_xyz nodelet_manager">
    <remap from="disparity/image"       to="$(arg camera)/disparity"/>
    <remap from="disparity/camera_info" to="$(arg camera)/right/camera_info"/>
    <remap from="cloud"                to="cloudXYZ"/>

    <param name="voxel_size" type="double" value="0.05"/>
    <param name="decimation" type="int" value="4"/>
    <param name="max_depth" type="double" value="10"/>
</node>

<!-- Create point cloud for the local planner -->
<node pkg="nodelet" type="nodelet" name="obstacles_detection" args="load rtabmap_ros/obstacles_detection nodelet_manager">
    <remap from="cloud" to="cloudXYZ"/>
    <remap from="obstacles" to="/planner/planner_cloud"/>

    <param name="frame_id" type="string" value="artemisBody"/>
    <param name="map_frame_id" type="string" value="map"/>
    <param name="min_cluster_size" type="int" value="20"/>
    <param name="max_obstacles_height" type="double" value="0.0"/>
</node>

or

<!-- Generate a point cloud from the disparity image -->
<node pkg="nodelet" type="nodelet" name="disparity2cloud" args="standalone rtabmap_ros/point_cloud_xyz">
    <remap from="disparity/image"       to="$(arg camera)/disparity"/>
    <remap from="disparity/camera_info" to="$(arg camera)/right/camera_info"/>
    <remap from="cloud"                to="cloudXYZ"/>

    <param name="voxel_size" type="double" value="0.05"/>
    <param name="decimation" type="int" value="4"/>
    <param name="max_depth" type="double" value="10"/>
</node>

<!-- Create point cloud for the local planner -->
<node pkg="nodelet" type="nodelet" name="obstacles_detection" args="standalone rtabmap_ros/obstacles_detection">
    <remap from="cloud" to="cloudXYZ"/>
    <remap from="obstacles" to="/planner/planner_cloud"/>

    <param name="frame_id" type="string" value="artemisBody"/>
    <param name="map_frame_id" type="string" value="map"/>
    <param name="min_cluster_size" type="int" value="20"/>
    <param name="max_obstacles_height" type="double" value="0.0"/>
</node>

Well, the first choice is preferred if cloudXYZ is used only by obstacles_detection nodelet (to keep transferred messages in memory).

EDIT Beware that the nodelets are in "/stereo_camera" namespace. If you want to remap disparity/image to artemis/navCam/disparity, make sure you set your argument "camera=/artemis/navCam" with leading slash. Otherwise, it may try to subscribe to "/stereo_camera/artemis/navCam/disparity".