mpa to ros voxl-tag detector

  • Hi,

    I am trying to get voxl-tag detector data by tracking camera in host PC, but it gives me some weird numbers that are not related to tag detection data. I use the roslaunch voxl_mpa_to_ros voxl_mpa_to_ros.launch in voxl and rostopic echo /tracking_tag_overlay in PC.Screenshot from 2022-09-06 16-06-03.png

  • Hi,

    You're echoing the tracking tag overlay, which is an image stream with the original image annotated with any detected tags, not a ros packet with information about the tags. You'll want to view this with rviz or rqt_image_view.

  • Hi Alex,

    How can I remotely access the data displayed by voxl-inspect-tags? I noticed that there were several ROS topics available:


    but none of those (tracking and tracking_tag_overlay) seem to be what I need.

  • Hi,

    I'm also interested in accessing this data, I noticed the voxl-inspect-tags code manages to access it but I'm not sure what is the proper approach to send it through MAVROS/Mavlink to an external flight controller. I tried the following things:

    • adding the libraries from voxl-inspect-tags that open the pipe associated with tags to a CMakeLists file in a ROS package, though it doesn't compile with an error message stating they're incompatible when running catkin_make

    • reading the "/tracking" ROS msg from within the kinetic docker and then:
      (1) use a standard ROS package for AprilTag detection, doesn't work as it requires catkin build which fails.
      (2) catkin_make a ROS package for AprilTag detection, but I didn't have any luck with compiling OpenCV in the docker.

    My ultimate goal would be to send this data to PX4 via UART for precision landing but so far I'm a bit lost and would truly appreciate an opinion on this. Would it be simpler to copy the process from voxl-inspect-tags and use mavlink directly to send it to the separate flight controller? If so how would one add mavlink messaging capabilities to the .c code? Or am I way off?

  • Did anything come of this?
    I'm also trying to access AprilTag location in ROS, but there's nothing obvious in rostopic list.
    I can't find any documentation on it either.

  • @Alex-Gardner Is there any way to get the tag X.Y.Z coords in ROS?

  • Hello, @Nicolas-Brissonneau:

    I am trying to do the same thing as you and am stuck with the same problem. Did you manage to solve it?

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