Game Development Reference
good. The stated accuracy is 0.1mm (0.15mm in depth) for a 1.3m
1.3m zone at
2.25m. The data transfer frequency can go up to 1500Hz. These accurate location
systems are relatively expensive and have been developed for the field of metrology.
Several systems using the near infrared spectrum in a confined space can disrupt
For example, the stereoscopic glasses of Stereographics use the near-infrared spec-
tral band to control the shutter of the glasses. However, these glasses are an ideal
medium for placing passive markers, and thus tracking the eyes. The ARTtracking
system, for example, solves this problem by synchronising its flash at a time different
than that at which Stereographics sends the command to the glasses.
In spite of their fairly high price, more and more users are getting attracted to opti-
cal trackers mainly because of their noise immunity. The main disadvantage of these
trackers is that the line of sight from the camera to the marker cannot be blocked.
Nevertheless, this point has been taken into consideration in the latest systems, mainly
due to the redundancy of cameras and markers.
Adelstein, B., Johnston, E. & Ellis, S. (1996) Dynamic response of electromagnetic spatial
displacement trackers. Presence , 5 (3).
Faugeras, O. (1993) Three-dimensional computer vision . Cambridge, MIT Press. ISBN 0-262-
Fuchs, P. (1996) Les interfaces de la réalité virtuelle . Les Presses de l'Ecole des Mines de Paris.
Horaud, R. &Monga, O. (1995) Vision par ordinateur, outils fondamentaux . Editions Hermès.
Raab, F. & Blood, E. (1979) Magnetic position and orientation tracking system. IEEE
Transactions on Aerospace and Electronic Systems , 15 (5), 709-718.
Welch, G., Bishop, G., Vicci, L., Brumback, S., Keller, K. & Colucci, D. (1999) The hiball
tracker: High-performance wide-area tracking for virtual and augmented environments. In:
Proceedngs of the ACM Symposium on Virtual Reality Software and Technology 1999
(VRST 99) .
Websites of the companies mentioned above
Systron Donner Inertial Div.