Head tracking a Head-Mounted Display (HMD) with VRMeer and VRPN

Head tracking test with a Polhemus Fastrak and the Visette Pro Head-Mounted Display. I use our OpenSceneGraph-based VRMeer software through python, and use VRPN tracking software to poll the sensors. The scene is a simple textured box created in Blender and exported to a Wavefront OBJ file with textures pre-baked.

One tricky part here is getting the calibration "just right" in the sense that head rotations also trigger a little bit of translation in the camera. In my specific view setup, the virtual screen is at a virtual 50cm from the eyes, and this screen should "float" through the scene (actually, the screen is static and I apply inverse transformation to the scene).

Category:

Science & Technology

Tags:

• hmd
• head mounted display
• virtual reality
• graphics
• tracking
• tracker
• immersion

[clowngerrie]

There is influence from metallic components, but we try and avoid to have that close to either the emitter or the receiver. You could get funny results, just as we experienced with a "hidden" steel bar underneath a wooden table, which would "bend" space. Or, when the sensor is positioned too close to active electronic circuitry in the HMD. You can improve performance of the tracking by performing some sort of grid-based calibration.

[paulmabbutt]

How accurate do you find the Polhemus Fastrak? I've read the specs that it shouldn't be affected by electrical equipment, but interested to know if this is true in practice. I know some trackers need re-calibrating every so often, especially magnetic trackers. Is this the case with this one?