OAK-D Pro W PoE – Many null/zero depth values

Eneko

I’m having an issue with depth images from two OAK-D Pro W PoE cameras.

Both cameras are using exactly the same code, settings, and environment, but their behavior is inconsistent. Sometimes the depth works well, but other times one or even both cameras return depth frames with a very large amount of null/zero pixels, making the depth map almost unusable.

An example of depth image:

The only thing I change is the device (serial number). The rest is identical: same script, same pipeline, same host machine, same lighting conditions, same distance to objects, etc.

In the code, depth is computed using the StereoDepth node with the following configuration:

HIGH_ACCURACY preset
Left-right check: enabled
Subpixel: enabled
Median filter: 3x3
IR projector intensity: 0.9 (to improve texture on smooth surfaces)

Because the same setup sometimes works well and sometimes produces a huge amount of null pixels, I’m wondering if this could be related to:

A hardware issue
A calibration problem
Or some specific configuration or runtime condition that could cause unstable or invalid depth output

Has anyone experienced something similar?
What additional tests or diagnostics would you recommend to understand whether this is a device problem, calibration issue, or a configuration problem?

Thanks in advance for your help.

OskarSonc

Hey Eneko - eros in the depth frame are almost always “invalid disparity” (StereoDepth rejected the match), and with HIGH_ACCURACY + LR-check + subpixel it can get very strict, so small AE/IR/texture changes can flip you from good to mostly invalid.

To narrow it down quickly: try locking mono exposure/gain, lowering IR projector intensity, and then toggle LR-check / subpixel (one at a time). Also stream rectifiedLeft/rectifiedRight + confidence/disparity and confirm their sequence numbers match on “bad” frames.

Which connection are you using (USB or PoE/Ethernet), and does the issue consistently happen on the same device or does it “move” between them?

Thanks,
Oskar

Eneko

Hi Oskar, thanks a lot for your quick response.

I’m going to try making the StereoDepth configuration less strict. Specifically, I’ll switch to HIGH_DENSITY + LR-check (LR-check is required in my case, otherwise I get this error:
[StereoDepth(3)] [error] Disparity/depth CENTER alignment requires left-right check mode enabled!), lower the IR projector intensity to 0.5, and disable subpixel only, to see how this affects the amount of invalid depth.

Regarding your questions:

I’m using a PoE / Ethernet connection.
The issue usually happens on the same camera. On a few occasions the camera that normally works fine has also failed, but that is very rare.

I’ll test these changes and get back to you with the results.

Thanks again for the help.

OskarSonc

Hey Eneko - also maybe you could do manual/dynamic calibration on the camera that is having the problmes since calibration is the only thing different on your two cameras...

Eneko

Hey OskarSonc, thanks.

I ran some tests and after relaxing the StereoDepth settings and lowering the IR, the depth looks much better now. However, the error is still quite large: for objects at ~10 m, I’m getting around ~12 m.

An example of the new depth:

I’ll try manual/dynamic calibration on the problematic camera. But I wanted to ask: is this level of error at ~10 m expected for OAK-D Pro W, or are there recommended ways to reduce it?

OskarSonc

Hey Eneko - glad it's better.
I would suggest you do a manual calibration, yes.
You can look at this page for what the expected accuracy should be and this page for improving the accuracy

Hope this helps,
Oskar