Tracking a head - mounted display in a room - sized environment withhead - mounted

This paper presents our eeorts to accurately track a Head-Mounted Display (HMD) in a large environment. We review our current benchtop prototype (introduced in WCF90]), then describe our plans for building the full-scale system. Both systems use an inside-out optical tracking scheme, where lateral-eeect photodiodes mounted on the user's helmet view ashing infrared beacons placed in the environment. Church's method uses the measured 2D image positions and the known 3D beacon locations to recover the 3D position and orientation of the helmet in real-time. We discuss the implementation and performance of the benchtop prototype. The full-scale system design includes ceiling panels that hold the infrared beacons and a new sensor arrangement of two photodiodes with holographic lenses. In the full-scale system, the user can walk almost anywhere under the grid of ceiling panels, making the working volume nearly as large as the room.