Game Development Reference
Figure 6.9 DynaSight system of Origin Instruments Corporation. (Illustration: Origin Instruments
Corp., with permission)
Figure 6.10 OPTOTRAK Certus by North Digital and its operating principle
The optical tracker DynaSight (Figure 6.9) of Origin Instruments Corporation is a
sensor which is rather old, but has the merit of being economical. This compact tracker
measures the three-dimensional position (3DOF) of a light-weight passive target at a
frequency of 65Hz. It can be easily mounted on a pair of stereoscopic glasses. It
operates in the near infrared region over a span of 75 ◦ elevation
75 ◦ azimuth
(target of 7mm) to 5m (target of 50mm) depth. The latency is satisfactory (9 to 28ms).
The lateral accuracy and depth accuracy is 2mm and 8mm respectively. A group of
several (up to 4) additional “Active Target Adapter'' devices, each consisting of three
active targets, gives a 6DOF tracker.
With three linear cameras mounted on a beam of about one metre, the Optotrak
Certus system of Northern Digital Inc (NDI) can give the position of infrared emit-
ting diodes (up to 512). Linear cameras, equipped with cylindrical lenses, have better
resolution and a greater reading frequency than matrix cameras (Figure 6.10).
“Pencil'' pointers are covered with 24 diodes, making it possible to get rid of
blanking problems during the handling of these pointers. The characteristics are very