Zed-ros-wrapper: High-variance depth errors for flat surfaces

[ana-GT]

Hi. I intend to use our ZED camera for robot perception (passing pointclouds to an octomap in order to perform collision detection). I am observing that the pointcloud output of the ZED camera is highly variant, for surfaces such as walls. In the picture attached, you can see a pointcloud obtained with the ZED camera and the picture of the scene to the left: The wall behind the robot arm appears highly curved (actually, the wall's points appear as if in contact with the upper part of the arm, which is at least half a meter away from the said wall) . Is this behavior normal, and if not, could you kindly recommend an approach to reduce this error? (or perhaps any parameter I might need to further adjust?). The picture shown was obtained by using NO filtering (I attempted to use different confidence values and the results were far worse).

Thanks!

PS.- I already recalibrated our ZED with the ZED Calibration executable (there is not noticeable difference in results by doing that, either). I am using Ubuntu 16.04, with a GeForce GTX 770 graphics card and with the SDK v2.0. I set the input default to be HD720 at 60 fps).

[adujardin]

Hi,

You can change the depth quality parameter in the launch file. Update this line and put the value 3 to get the best available depth quality, a GTX 770 will easily handle it.

In the upcoming release (ZED SDK 2.1), we added a depth stabilizer mode which significantly improves the precision and the stability of the depth map (it uses the positional tracking). We will update the ROS wrapper accordingly once it's available.

[ana-GT]

Hi @adujardin,

Thanks for the suggestions. I changed the quality parameter and the results are rather similar (there appear a few extra holes with the higher quality parameter, though).

Is there any estimated date for the release of the 2.1 ZED SDK? I am trying to figure out if I should try to improve the results with some filtering on my own in the left/right pairs or if it would be just better to wait for the next release.

Thanks!

[adujardin]

The official release should be within a couple of weeks.

You can contact the support at [email protected] to get a beta version of the 2.1. In that case, you should mention this issue to get a pre-version of the ROS wrapper.

[ana-GT]

@adujardin, Thank you very much! Just sent an email. Looking forward to try the beta version if possible.

[chaitanyantr]

hi @ana-GT ,

May i know what is the launch file for your 3d-map in octomap_server.

I'm trying to create a octomap with zed,bit bewildered what inputs from zed camera i have to give to octomap to create the map.

my_launch_file is...

    <!-- fixed map frame (set to 'map' if SLAM or localization running!) -->
    <param name="frame_id" type="string" value="/zed/zed_node/pose" />

    <!-- maximum range to integrate (speedup!) -->
    <param name="sensor_model/max_range" value="5.0" />

    <!-- data source to integrate (PointCloud2) -->
    <remap from="cloud_in" to="/zed/zed_node/point_cloud/cloud_registered" />

</node>