My company has been using your ZED 2i cameras in our product for a few years now. We make use of zed-open-capture to pull raw frames off of the camera, and then run them through an AI processing pipeline to produce relevant results. In general, we are pleased with the performance of the hardware, and are glad that you’ve provided an open-source library which can capture images without needing access to precious GPU resources.
Recently we ran into a difficult bug on one device: when using HD2K resolution, the crop region on the left image only was not in its normal location. That is, the left image’s area was shifted left by ~150px. This resulted in the (calibrated) depths being short by approximately 30 cm.
We determined the crop region shifted based on:
Comparing static image content during and after the issue.
Reproducing the depth error by applying a -150px horizontal shift to good frames.
Correcting the issue by applying a +150px shift to the faulty left image.
Image resolution and file sizes were correct.
The issue appeared after a device (Jetson+ZED camera) power cycle, and we were able to resolve it by restarting our service (which re-initializes the camera via zed-open-capture). No errors or warnings were emitted during the problem.
Is there any way that we can detect (or prevent) this crop region issue in the future?
For our client’s privacy, I cannot share the full image publicly. However, I will send an email to support@stereolabs.com with the unaltered version.
Basically our camera is surrounded on either side with some netting material which can be seen along the left and right side of the left and right image respectively.
These images were taken 9s apart, during that time the service was restarted (i.e., restarting zed-open-capture’s process). Notice how initially the netting is covering more of the left image than after the restart where it is back to the normal position. I want to stress that the netting did not move.
While we’ve logged hundreds of thousands of hours of reliable operation, this issue is critical and needs to be understood to ensure it doesn’t recur.
Please let me know if I can provide any further details.
This discussion continued in a private email thread to avoid posting client information publicly. General summary in case others think they have a similar issue:
Walter has never seen the reported issue before
Confirm that there were no physical changes in your environment
Check your camera’s calibration accuracy as a bad calibration can cause a large crop error (in our case above we were comparing unrectified images visually, and checking depths on rectified images)
Cropping from the full sensor resolution down to HD2K is performed by the internal ISP (on the ZED 2i camera)
If possible, use cheese or guvcview to see the raw images from the camera; this will bypass zed-open-capture and any custom software wrappers. If the stream presents with an offset, then the camera should be checked at a hardware level
The ZED 2i does not perform any kind of onboard computation and does not have onboard capabilities to detect frame issues
