OSVR HDK2 software

[Ralph Campbell]

I have been trying to integrate the OSVR-Core library with the monado library in order to add position tracking to the current orientation only tracking.

I basically took the code from OSVR-Core/plugins/unifiedvideoinertialtracker and added it to monado/src/xrt/drivers/hdk.

However, the OSVR code is very complicated and I'm lost in all the coordinate transformations and Kalman filtering.

Does anyone have suggestions how I might proceed?

https://gitlab.freedesktop.org/monado/monado.git

https://github.com/OSVR/OSVR-Core.git

[Chris Albertson]

On May 8, 2026, at 11:24 PM, Ralph Campbell <ralphca...@gmail.com> wrote:

 I'm lost in all the coordinate transformations and Kalman filtering.

I said the same thing a while back

These two things helped in a big way

1) https://www.khanacademy.org/math/linear-algebra

2) https://robogrok.com/. after years of forgetting this 100 times the instructer here finally makes Homogeneous Transformation Matrices easy and understandable. assuming #1 above is under control.

I had taken this stuff in school but that was in the 1980s.  Kalman filters and coordinate transforms ( and modern AI too) are so dependent on Linear Algabra that it needs to be nearly second nature.   A real mathematician would find Khann’s course lacking but he covers what you need to know if you want to use it and skips most proofs.  Just what an engineer wants.

Both instructers go painfully slow but, believe me, I studied education (teaching after retiring from engineering) and both these people are VERY good at teaching and their method ensures you will remember.   Just put up withthe slowness and don’t skip. it is based on good science.

I think most of us who have problems understanding something are not dumb but just lack prerquistic skills

I wanted to figure out how to move 12 motors all at different speeds and acceleration so as to move a 4 legged robot walk while also controlled body roll pitch yaw and hight over ground.   Seemed intractable but that class (#2) at ASU made it pretty trivially simple.   No these are not 10 minute YouTubs videos.  both are targets at 2nd year university students and cover basic theory.

[Ralph Campbell]

FYI, I found these links very useful. I'm still trying to absorb it all and fix the position tracking and also why the images in the headset appear like double vision instead of a nice stereo image (probably due to some transform or distortion matrix not being correct).

https://lavalle.pl/vr/node1.html

Also, this is interesting for seeing the inside of the OSRV HDK2 headset:

https://www.ifixit.com/Teardown/Razer+OSVR+HDK+2+Teardown/65804