cannot subscribe to point cloud in RViz when use_intra_process_comms

[christian-rauch]

When I set use_intra_process_comms to true, it is not possible to subscribe to the point cloud in RViz2 via the /depth/color/points topic. But it is possible to subscribe to the images.

I assume this is because the point cloud message _msg_pointcloud is not published as unique shared pointer like the image messages.

[MartyG-RealSense]

Hi @christian-rauch The RealSense ROS wrapper provides instructions at the link below for intra_process_comms.

https://github.com/IntelRealSense/realsense-ros#efficient-intra-process-communication

Known limitations of the process include the /static_tf topic being disabled and compressed images using image_transport being disabled.

In regard to the static_tf issue, a RealSense ROS user submitted a PR to work around this limitation at #2381

[christian-rauch]

I don't see the point cloud messages mentioned in this documentation. With use_intra_process_comms set, I can subscribe to the point clouds on the command line but they do not show up in RViz.

I noticed that RViz prints [rviz]: Message Filter dropping message: frame 'camera_color_optical_frame' [...] for reason 'discarding message because the queue is full' when this happens. Do you think this is related to the tf and compressed image issues mentioned in the documentation?

[MartyG-RealSense]

The last time that I handled a discarding message because the queue is full error, a partial solution was achieved by reducing the FPS from 30 to 15, though the message still occurred but less frequently.

[christian-rauch]

This issue indeed seems to be caused by the missing transformations on /tf_static and not the point cloud messages per se. That was not clear from the error message. Rebasing and applying #2381 allows me to visualise point clouds in RViz when use_intra_process_comms is set.

[MartyG-RealSense]

That's great to hear that you found a solution, @christian-rauch - thanks very much for the update :)

[christian-rauch]

Closing this since the PR that fixes this issue has been merged.

[MartyG-RealSense]

Thanks very much @christian-rauch for the update!