ZED 2i – ROI unstable with FireNEX (450 m fiber), works with direct USB

Software
1

Hello,

I am still experiencing an issue with the ROI feature using a ZED 2i and TouchDesigner 2025.30250 (ZED SDK 5.0.2), and I would appreciate your guidance.

Related thread:
https://community.stereolabs.com/t/roi-feature-not-working-with-stream-4-1-x-and-svo2/9313

We previously used a Jetson Nano for streaming, which already caused ROI issues.
The Jetson has since been removed and replaced with:

  • Connection: NewNex FireNEX-80G (USB-over-fiber)

  • Fiber length: ~450 m single-mode fiber (rated up to 700 m)

Issue
When ROI is enabled:

  • Body detection often drops to 0 detections, even with people clearly visible

  • Detection may work briefly, then stop

  • Toggling ROI can temporarily restore detection, but it is unstable

Without ROI:

  • Camera streaming is stable

  • Body tracking works normally

Control test
I tested the exact same TouchDesigner project at home:

  • Same software versions

  • Same ROI configuration

  • Direct USB 3 connection (no extender)

ROI works perfectly and consistently in this setup.

This suggests the TD project and SDK usage are correct, and the issue is related to the on-site setup.

Questions

  1. Could this behavior indicate a camera hardware / calibration / sensor sync issue on the on-site ZED 2i?

  2. Are there known ROI sensitivities to USB-over-fiber links, even when bandwidth and streaming appear normal?

  3. Are there additional diagnostics or verbose logs (beyond the ZED Diagnostic Tool) to check timing or synchronization issues affecting ROI?

My goal is to determine whether this is more likely:

  • a camera-specific issue,

  • a limitation of long USB-over-fiber links,

  • or a configuration detail I may be missing.

Thank you for your help,
Xavier

2

Hi @xvgt
What you described is a weird behavior we are not aware of, so we need more information to try to understand the causes of the issue.

  • When you enable ROI, is the frame rate consistent, or do you notice any slowdown?
  • What’s the configuration of the ROI feature? Do you apply it to all the modules or only to Body tracking?
  • Please connect the camera to the Fiber extender, then open the ZED Sensor Viewer tool and check that all the sensor data is received correctly. Please take a few screenshots of the Accelerometer, Gyroscope, and Orientation plots and share them.

It’s a possibility; we must learn more about the problem.

We are not aware of any kind of problem like these.

Normally, there are not.

3

Hey,

This is a follow-up on this topic : https://community.stereolabs.com/t/zed-2i-roi-unstable-with-firenex-450-m-fiber-works-with-direct-usb/10655

I think that it will be easier to share the elements here.

  • When you enable ROI, is the frame rate consistent, or do you notice any slowdown?

No frame drop when activating the ROI or switching the ROI mask.

  • What’s the configuration of the ROI feature? Do you apply it to all the modules or only to Body tracking?

Only the 3D body tracking - skeleton 18 joints is active in Touch Designer .

All the sensor data is received.

Enclosed the screenshot for the sensors, firmware, the diag .json

In case it could help, I have enclosed 2 videos showing the issue.

ZED_ROI_Debug switching ROI.webm :
ROI is active, just switching between a full frame ROI ( detection work) , and a smaller mask = detection doesn’t work even with people in the frame

ZED_ROI_Debug Activating ROI.webm :
Activation and deactivation of the ROI in the zedTop operator .

[Screenshot 2026-01-22 142913.png]

The same result is obtained with both methods: no detection or randomness when either ROI is active with a mask smaller than the full frame.

I tested the ROI feature with a ZED2i (similar firmware) connected via USB3 or streamed via Zed Explorer and using the same version of Touch Designer (SDK5.0.3), and it worked perfectly.

This is exactly the same issue that we encountered previously when using a Jetson Nano to stream to the host. The ROI didn’t work; it was a very similar inconsistency to that seen in this case: https://community.stereolabs.com/t/roi-feature-not-working-with-stream-4-1-x-and-svo2/9313

Could it be a specific type of data loss or latency that the ZED SDK’s Body Tracking + ROI module cannot handle in both cases?

best regards,

Xavier Gruchet //
XvGt

+33 620 434 174
/>Pixelux.tv // Xvgt.io

4

Hey @Myzhar
Thanks for your prompt answer. We struggled for so long ….

I emailed to Support — it’s easier to share the elements and videos that way. If we manage to resolve the issue, I will share the final result for future reference.

best,

5

Hi Xavier,
Thank you for the videos and the additional information.

We are trying to analyze the issue because we cannot understand how it is possible that the fiber cable extender can cause this behavior.

Please do not hesitate to add any additional information if you have any. Meanwhile, we are trying to replicate the problem at our labs.

Best regards,

Walter

Walter Lucetti
Senior Computer Engineer
SDK / Robotics / HW
Stereolabs Support