How can I reduce point cloud size with ros driver?

[bartonp2]

I have an OAK-D Pro PoE Fixed Focus camera which I am launch with the ros driver. I only need the pointcloud with 3Hz and would like to reduce the resolution of the point cloud as well, such that I don't have to do it within software. I am able to set the resolution of the rgb and left image, however, upon changing the width and height of the right or stereo image, I get the following error:

[INFO] [launch_ros.actions.load_composable_nodes]: Loaded node '/point_cloud_xyzi' in container 'oak_container'               
[component_container-1] terminate called after throwing an instance of 'cv::Exception'                                        
[component_container-1]   what():  OpenCV(4.2.0) /home/ubuntu/build_opencv/opencv/modules/core/src/matrix.cpp:768: error: (-21
5:Assertion failed) 0 <= _rowRange.start && _rowRange.start <= _rowRange.end && _rowRange.end <= m.rows in function 'Mat'     
[component_container-1]

Here is the config I am using:

/oak:
  ros__parameters:
    rgb:
      i_publish_topic: false
      i_fps: 3.0
    left:
      i_fps: 3.0                  # Also defines the point cloud fps - 2fps leads to auto exposure problems, other fps seem to work
      i_width: 640              
      i_height: 400
    right:
      i_fps: 3.0
      # i_width: 640              # cannot seem to set right to 400p. Works on left
      # i_height: 400
    stereo:
      i_publish_topic: true       # point cloud not published without this
      i_align_depth: true
      i_board_socket_id: 2
      i_subpixel: true
      i_publish_right_rect: true  # needed for point cloud to be published
      i_right_rect_synced: false
      # i_width: 640              
      # i_height: 400
    camera:
      i_nn_type: none
      i_enable_imu: false

What is the recommended way to change the resolution of the pointcloud and which other settings are required for it to work?

[Serafadam]

Hi, to properly set width/height you should start with i_resolution parameter (set left/right.i_resolution: 400P, width and height should be updated automatically)

[gurbain]

Hello,

I am facing the same problem here with an OAK-D. Is there an example somewhere with reduced size pointcloud? I think that it is quite useful in some robotics application. With these parameters:

/oak:
  ros__parameters:
    camera:
      i_pipeline_type: RGBD
    stereo:
      i_publish_topic: true 
    right:
      i_resolution: 400P
      i_fps: 5.0
      i_low_bandwidth: true
    left:
      i_resolution: 400P
      i_fps: 5.0
      i_low_bandwidth: true

The point cloud is published in 1280x720p. And If I change it to:

/oak:
  ros__parameters:
    camera:
      i_pipeline_type: RGBD
    stereo:
      i_publish_topic: true 
      i_height: 400
      i_width: 640
    right:
      i_resolution: 400P
      i_fps: 5.0
      i_low_bandwidth: true
    left:
      i_resolution: 400P
      i_fps: 5.0
      i_low_bandwidth: true

I get the error:

 what():  OpenCV(4.5.4) ./modules/core/src/matrix.cpp:768: error: (-215:Assertion failed) 0 <= _rowRange.start && _rowRange.start <= _rowRange.end && _rowRange.end <= m.rows in function 'Mat'

Any idea? thank you

[bartonp2]

Great, thanks this worked @Serafadam 👍

However, I noticed that having installed the depthai-ros-driver via apt, I do not have the latest code. Maybe this is causing some problems for @gurbain .
I am on Ubuntu focal 20.04, aarch64-linux-gnu and installed ros-humble-depthai*

[Serafadam]

@gurbain This is because stereo is aligned to RGB sensor which has the size of 1280x720, to use alignment and get low resolution you would need to set desired ISP scaling (num/den) parameters.

@bartonp2
ROS releases are not instant, packages will be updated to latest version with the next sync

[bartonp2]

@Serafadam When can we expect such a sync or is there some way to track this?

[Serafadam]

I would expect that the packages will be released within the week as last one was around month ago, you can check for updates on ROS forums https://discourse.ros.org/tag/release
You can also use testing repository to get the latest binaries https://docs.ros.org/en/jazzy/Installation/Testing.html