Rotational drift, even with a lighthouse

Last night, my 8K kept drifting to the left, even though I have a (single) base station (lighthouse). I’ve never seen this before. The drift was quite noticeable; I had to recenter every 2-3 minutes. I know it was tracking; if I turned away from the base station, the headset panels went gray.

It might have been because (for the first time) I didn’t open PiTool, before starting my game. I think I’ll reboot everything first, just to be sure everything is reinitialized.

Has anyone seen this behavior?

I’ll retest tonight and post my findings in this post.

Maybe you did have something that mirrored just then so tracking got fubar.

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Something certainly got fubarred. The only thing I did outside of my normal routine was to skip running PiTool. I’ve not seen this before, so I’m hoping there’s not some sort of hardware defect causing this irritating behavior.

You must start pitool otherwis stem dont see the headset.

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I’m willing to believe omitting PiTool triggered the problem, but my understanding is that running PiTool is supposed to be optional. I was playing Elite D from the game-launcher (not Steam) and SteamVR started as usual. I was able to play in VR just fine, except for the drift.

Maybe you have not ticked out so pitool auto start with windows.

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I had an Xbox controller where one of the joysticks was stuck very slightly to the right, I would get the drift and I thought it my Pimax 4K was just getting worse, as you know they had some drift…


I’ve had this a few times when I forgot my xbox 360 controller was plugged in.


Good point. That’s something I will definitely double-check. My HOTAS is only a couple of months old and is still in the breaking-in phase. I’ve already had to increase the dead-zone once.

Mine is wireless, so it’s absolutely off. I did run into a similar problem once: I was using my controller, but I kept spinning in circles, until I unplugged my joystick/throttle (Logitech Extreme 3D Pro).

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Restarting the Pi service and rebooting the headset didn’t fix it. I’ll try a full reboot and maybe clean the front of my base station, but not until tomorrow night.

The drift is tolerable, only because I use VoiceAttack, so all I have to do is say “recenter”, but I have to do that every couple of minutes.

if its related to hardware or pitools then you should see the same problem in steam home environment or any other game/experience (preferable one that does only supports vive wands)


I’ll try the SteamVR environment tonight. I did see the problem last night in the start-up hanger in Elite D, which ignores Joystick movement when the menu is up, so I’ve ruled out the joystick as an issue.

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I think that the drift may be caused by my nearby room fan. The problem is greatly reduced when the fan is off. Unfortunately, it’s hot in my room and it will stay that way until autumn.

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maybe you can cover the fan (blades?) with something that does not reflect in IR or replace the fan with a differen tmodel that hase wooden blades?

Unfortunately, I don’t think that would help. I suspect that the fan motor is producing a strong enough magnetic field to interfere with the angle tracking sensors. (Also, the blades are plastic.)

So the gyro tracking stays on even when you are using the lighthouse tracking?


Yes, that’s my understanding. The lighthouse(s) are only used for the x, y, z positions. I also thought that a LH serves as a fixed reference point for the angles, but I’m not sure that’s true (otherwise, I shouldn’t be having a drift problem).

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AFAIK the Vive doesn’t have a gyro so if that’s the case it’s something Pimax has come up with.

Pretty sure SteamVR tracking doesn’t require a gyro.

EDIT: Guess I was wrong:

The Vive has an internal gyroscope & accelerometer for rotation, not sure why those couldn’t be used indipendantly from positional tracking…


if its the motor then it should vanish when it has no power
also most smartphones do have a Magnetometer, so it can be measured in way

Which is what lead me to suspect the fan.

Oddly, if I start with the fan on, my headset drifts to the left and if I then turn the off, it drifts to the right. If I start with the fan off and don’t turn it on, the drift seems to be gone, but it’s difficult to play, because the lenses keep fogging up from all my sweating. I need the fan on to play comfortably. Unfortunately, I can’t just move the fan, since there’s really only 1 spot where it fits in my small home office.

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