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Parallel use of Vive and Qualisys Motion Capturing causes interference


Ramalam
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Hi, 

I'm trying to do motion capturing (via Qualisys M3 cameras) while in VR with Vive Pro running on SteamVR 1.6.10

I've attached a scheme of the room + camera setup. All cameras are attached to a rig beneath the ceiling about 2.7m above the floor.

Red dots = Motion Capturing Cameras
Green dots = Vive Cameras
Blue canvas = Vive Tracking Space 

Problem

The motion capture cameras cause interference with Vive Cameras, when used at the same time.
The Vive Cameras run with 60hz. The Qualisys cameras run with 100-120hz. 

What could I do, to prevent the Vive and Motion Capturing Cameras from causing interference? 
In this thread I've read that IR issues are probably the reason for unstable Vive tracking.
Is there a way to make the Vive Cameras go by a different frequency than the Qualisys Cameras? (from what I know Vive Cameras can only switch between 30 and 60hz)

Thanks in advance.

Room Setup.png

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@Ramalam, I don't have hands on experience with Qualisys systems but everything I said in the linked thread would still apply here. It's not the operational frequency of the systems - it's that the Qualisys would be putting out high intensity IR signal which SteamVR sensors will treat as a persistent sync signal. If the cameras are outputting IR light in the exact frequencies that the sensors are sensitive to (Specifically ~800-850nM), that signal will be detected by the sensor and treated as a "IR flash" if the intensity of light is above the sensor's threshold of detection.

Usually in these cases where you have a high precision IR tracking system, you would replace SteamVR's tracking system with the motion capture system by placing tracking fiduciaries on the headset and controllers and then integrating the supplier's (Qualisys') SDKs to drive software support. I've seen one case where someone was able to use polarizing filters on the cameras, the headset, and the stations to ensure the SteamVR tracking system's IR light was isolated from the tracking system's light but it's a janky solution at best - the controllers each have 24 sensors a piece for example and since they're moving around in 6DoF, as they rotate, the plane of light that's allowed to pass through the filter will shift.


Vive is not camera based. Please watch the entirety of this video to get a better understanding of how SteamVR tracking works so you'll understand what I mean by "IR Flash" and what effect the cameras have on the system. You cannot modulate the frequency of the base-stations (which are 60hz a piece (3600RPM), 120 hz interleaved) and modulating the frequency wouldn't actually matter because it's the intensity and wavelength of the IR light, not the speed of the emission that's causing the interference.

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  • 3 weeks later...

Thank you for your help! 

I'm using two SteamVR Base Stations 2.0 and the interference occurs, as soon as I increase the exposure time of the IR-Tracking Cameras (Qualysis). A link cable between both Vive sensors didn't help. You already pointed out, that a modulation of the frequency wouldn't make a change, so would you confirm that there's no chance to let the IR-System and the Vive Sensors operate alternatingly? So that while the IR-Signal stops, the Vive sensors do their sweep?

 

@Synthesis  @VibrantNebula

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  • 7 months later...

@Ramalam Hi,

I'm working at Qualisys and just noticed that you are having problems with SteamVR Base Stations 2.0 and a Qualisys system. In our tests it has worked fine with Base Stations 2.0, without any interference. However, the older Base station 1.0 doesn't work with a Qualisys system, because of the IR interference. Can you please contact us at support@qualisys.com if you are still having issues.

Regards,
Johannes

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