
120 Virtual Reality: Concepts and Technologies
good. The stated accuracy is 0.1 mm (0.15 mm in depth) for a 1.3 m × 1.3 m zone at
2.25 m. The data transfer frequency can go up to 1500 Hz. 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
each other.
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, ...