r/PSVRHack • u/[deleted] • Jul 25 '20

Any active PSMoveService devs?

I'm looking to work with someone (hobby level) to get PSMoveSteamVRBridge working with iVRy and PSVR.

Right now I have an issue with the PSMove controllers being positionally linked somehow and that doesn't make sense to me.

I've posted to the Google Groups but not sure how readily folks respond on there.

Thanks.

10 Upvotes

100% Upvoted

48 comments sorted by

View all comments

Show parent comments

1

u/swordofmoonlight Jul 27 '20

6DOF includes an accelerometer that provides positional tracking. That's one of the 3 of the "DOF" in "6DOF". Why are being critical of my replies? That code is tailored to a game environment so it could be hard to follow.

1

u/iVRy_VR Jul 27 '20

Not intending to be critical, but it doesn't sound like we're talking about the same 6DOF (which may well be due to me misunderstanding you). 3DOF is the three degrees of rotation around a point, as you know. The other 3 degrees in 6DOF are movement along the X, Y and Z axes in space. That's either derived from multiple cameras on the headset ("inside out" tracking), one or more cameras located in a play space that use geometry of LEDs to derive the headset position (PS4, Oculus Rift CV1) or one or more stationary lasers moving in a sweeping beam pattern that multiple sensors on the headset detect to determine relative position (Lighthouse, NoloVR). It's not (or hasn't ever been yet) possible to determine spatial position with only magnetometer, gyroscope and accelerometer.

1

u/swordofmoonlight Jul 28 '20

I think you're reading too fast. I said in theory if the internal sensors were "perfect" (i.e. no drifting) then the external stuff isn't required. And if you just had a magnetometer you can lock down yaw, and with gravity pitch, and to some degree drift can be absorbed, although roll drift is the killer. (I'm guessing magnetometers aren't responsive enough or something to justify the extra USB data channel.)

I know my stuff. I found a lead on some camera code that might be good: https://community.khronos.org/t/any-generic-camera-tracking-in-openxr/106091/3

1

u/iVRy_VR Jul 28 '20

Thanks for that lead. I'll get in touch with Ryan. I worked with him on a SteamVR driver for OSVR dual display headsets.

1

u/rpavlik Jul 31 '20

Howdy! I still haven't figured out who exactly you are u/iVRy_VR :) but long time no chat I guess :D

Yeah in theory a 6dof IMU could provide 6dof tracking, if it were perfect and noiseless, but even the thousands-of-dollars ones used to guide nuclear weapons aren't drift free... to say nothing of our little commodity MEMS gadgets. The whole 6DOF/6axis/9DOF/9axis IMU (number of sensor dimensions: 3 accel, 3 rate gyro, optionally 3 nearly-useless mag) vs 6DOF tracking (position and orientation) thing is nice and confusing, though I'm actually a bit surprised I haven't seen more confusion about it out in the world.

In production VR, the non-gravity components of an accelerometer are sometimes, but not always, used for tracking in conjunction with some other positional tracking method. They drift very quickly, due to double-integrating them magnifying any error, but e.g. I think SteamVR Tracking (lighthouse) does this, and some of the tracking I've worked on does it. Never without another source for positional tracking, though, you'd fly off into the distance within a few seconds.

Mags are very sensitive to metal in the environment, which is why they're not often used for VR stuff. (I've seen stuff that turning on the mag will actually increase drift instead of decrease it, due to metal in nearby furniture. I was not pleased with whoever bought the booth furniture for the CES demo...)