Gemini 435Le Hardware Triggering/Sync issues

Technical Support & Q&A
1

I have a problem with the hardware trigger functionality of these cameras.
From what I can understand the hardware trigger is supposed to train the camera to follow an external trigger at 10hz. If you feed the same signal into multiple cameras, they should all trigger at the same time.

With exactly the same configuration setup, same firmware (1.3.11) and a microcontroller running the hardware trigger, my 4 cameras drift away from the trigger by about a millisec every 5-10 seconds at 10hz. Not only that, the difference in frametime (using the output sync as a timing point, and with the camera facing a 10msec resolution clock) between the cameras varies from 1 - 140 msec. Its like the hardware trigger is doing very little to help with sync.

In an ideal world, I would want to trigger the camera at random times (not less than 100ms between triggers) but this doesn’t seem possible?

Sometimes, a camera will ‘behave’ and follow the hardware trigger, but its not always the same camera. Normally, they seem to go into free-run mode and just spit out data.

Can anyone provide some help? Is there a setting I am missing?

I have also tried running them in secondary mode, with similar results.

Yes, this is similar to Gemini 435Le hardware triggering problems which has no responses.

2

You may refer to this website for more detailed instructions. doc.orbbec.com/documentation/Camera Accessories/Set up Cameras for External Synchronization

3

Thanks Wan, I have read that document, but I’m not sure just how much I can use as there is no mention of the Gemini 435Le model capabilities/limitations. Is there any chance this document may be able to be updated by Orbbec?

If a camera provides an input hardware trigger, I expect it should take an image/frame when that trigger is activated. If this is not the case why have a hardware trigger input?

Also, I should not need to buy a sync controller. I have a perfectly good sync source in my microcontroller, that I can monitor and start/stop easily.

4

Hi @Dave.Haddon ,

were you able to solve it?
We are facing the same problem and cannot find any documentation for the 435Le.

@wan Is there any dedicated documentation that you can provide?

5

Kind of… it’s more of a workaround.
What works for me:

  • Set the microcontroller to output a 110 nsec pulse at either 5hz or 10hz.
  • Set the camera to use the SECONDARY_SYNC mode and the same rate as well.
  • Use separate processes to connect to each camera.
  • Capture all the images/files to a RAM drive /dev/shm or the like
  • Copy the data that you want to keep to persistent storage.

Doing it this way, I am able to keep a <10msec sync between 4 cameras.

It is not the way I wanted to do it, but it mostly works. I still get a few dropped frames and rgb-depth ply files, but its good enough.

Hope this helps.

6

Thanks for your reply. I just saw that a new firmware was released two days ago which looks promising to solve our problem. Maybe it solves yours as well: Release Gemini 435Le Firmware · orbbec/OrbbecFirmware · GitHub