Revision history [back]

I ran into the same problem while running markers.launch. The key being the error message stating a type mismatch in the topics. I believe it has something to do with the order of arguments while initializing the ar_track_alvar node.

To fix it, change

  <node name="ar_track_alvar" pkg="ar_track_alvar"
        type="individualMarkersNoKinect" respawn="false" output="screen" 
        args="$(arg marker_size) $(arg max_new_marker_error) \
              $(arg max_track_error) $(arg cam_image_topic)  \
              $(arg cam_info_topic) $(arg output_frame)" />

to

  <node name="ar_track_alvar" pkg="ar_track_alvar"
        type="individualMarkersNoKinect" respawn="false" output="screen"> 
        <param name="marker_size"   type="double" value="$(arg marker_size)"/>
        <param name="max_new_marker_error"  type="double" value="$(arg max_new_marker_error)"/>
        <param name="max_track_error"   type="double" value="$(arg max_track_error)"/>
        <param name="output_frame"  type="string" value="$(arg output_frame)"/>

        <remap from="camera_image" to="$(arg cam_image_topic)"/>
        <remap from="camera_info" to="$(arg cam_info_topic)"/>
  </node>

Using parameter names and remap makes sure that the arguments are parsed correctly.