Center camera FrameSync causes brighter region in images

paulmurphy

We're encountering an issue with the OAK-D Pro PoE and OAK-D S2 that causes a region at the top of each frame to be brighter, as if the sensor is exposing longer for those lines.

The issue arrises when setting "FrameSyncMode=Input" for the center camera and setting "FrameSyncMode=Output" for either the Left or Right cameras.

The height of the brighter region appears to vary with the exposure settings of the center camera and its intensity varies with the frame rate of the center camera. This still occurs when center/left/right frame rates are equal.

Example script demonstrating the issue here: https://gitlab.com/pgmurphy/oak-d-debug/-/blob/main/oak-d-sync-issue.py?ref_type=heads

Is the FrameSync setting the best method to ensure exposures are synchronized between center and left/right cameras?

Perhaps there's something about our pipeline config that doesn't behave well with the FrameSync?

Best,

Paul Murphy

jakaskerl

paulmurphy
Looks like a FW issue. Setting the exposure time on RGB, but driving the FSYNC via L/R seems to not be accounted for. The RGB is a rolling shutter and does not support snapshot triggering like the OV9282 does. If you set the exposure time short enough, the issue is not present. Same thing if FPS is lowered enough.

Thanks,
Jaka

paulmurphy

jakaskerl

Hi Jaka, when you say "setting exposure time on RGB while driving the FSYNC via L/R seems to not be accounted for", do you mean that this could perhaps be resolved in future firmware?

Are you suggesting that with this pipeline I am using the RGB camera with FSYNC input in snapshot mode? Is there a way to explicitly use continuous mode with the FSYNC input on the RGB camera?

I made some adjustments to the example script (updated at Gitlab link). It seems the issue still occurs when Auto-Exposure is enabled for the RGB camera. In this case, the height of the brighter region varies as the RGB camera exposure varies.

Interestingly, the issue does not appear to occur when the RGB camera resolution is set to 1080p or 2024X1520 unless frame rates are set to 2 or lower

jakaskerl

paulmurphy do you mean that this could perhaps be resolved in future firmware?

Yes. Looks fixable.

paulmurphy Is there a way to explicitly use continuous mode with the FSYNC input on the RGB camera?

Pulses have to come at exactly the same time each trigger period - and reflect what is set via setFps().

I have forwarded this to the FW team to possibly fix.

Thanks,
Jaka

paulmurphy

jakaskerl Thank you!