Vive Pro Tracker latency (lighthouse 2.0 and no headset) with Unity

[potion]

Hi everyone,

We have a Vive Pro and a Vive tracker (with Lighthouse 2.0 base stations). We're trying to use a Tracker only without the headset with a Unity app. When the headset is plugged in it caps fps to 90Hz. But even without the headset we're still seeing some latency in tracking data although the app runs at 120Hz. We use pyopenvr Python library that works with OpenVR to grab tracker pose data. Data is transmitted over UDP on the same machine to a Unity app.

Does anyone know what the latency of a Vive tracker is? I've read articles claiming upto 240Hz. Is it possible that the lag is introduced somewhere in Unity?

Thanks!

[76561199000828873]

Hi potion, did you happen to figure out what was causing this latency? We are using the exact same setup (Vive Tracker with no HMD) but no pyopenvr, just the SteamVR Unity plugin.

What's weird is that there's visible (about ~200ms) latency from the tracker only when Unity's running through our Dell S718QL projector display (HD 60Hz). If I drag the running Unity app over to another monitor plugged into the same gpu there's no visible latency. I thought it might be an old cable creating the bottleneck but nothing else in the projector display experiences latency, just the Vive Tracker data in Unity.

UPDATE:

I've actually tried using the tracker on another platform: ran the example of the ofxViveTracker-OSC openFrameworks addon (python openvr sending OSC data to OF) with the same results, so it doesn't appear to be Unity specific.

[guidonzq]

Yes, 250Hz is what I recall for the tracking HW.

Normally your tracker receives visual signals from the Base stations and sends them as packets, via bluetooth, to the headset. when you do not use a headset the data will go to a steam usb receiver.
I'd suggest the following steps-

1) Ensure your firmware is up-to-date and maybe reinstall usb drivers using the steamVR/settings/developer tab.

2) Make sure the base stations are set up at the recommended positions- diagonally opposite corners of the room, and above head height. They should be securely mounted with the optic faces kept clean.

Additionally you could sign up to be a steamVR tracking licencee and you will get access to diagnostic tools to access the basestations that may help you.