Visual Displays

There are several types of possible displays: monitors, head mounted displays (HMD), booms, and projection systems. All can be used to provide wide-angle stereoscopic views of a virtual world. Monitors with stereo glasses are the most inexpensive and provide for the lowest level of immersion.

HMDs and booms are the most widely used displays in VR systems.

Head Mounted Display

Both of these place a pair of displays directly in front of the user's eyes. The displays can be CRTs (Boom) or LCDs (HMD). The CRTs give better image quality and higher resolution but are too heavy for a HMD. The LCD's usually only have a resolution of 320 x 200 pixels with color. Some HMDs have a modern version of Sutherland's Sword of Damocles, i.e., two screens alongside the head with the images projected onto half-silvered mirrors in front of the eyes. Thus, the user sees not only the images but also the real world and the two appear to merge.

A projection-based system projects the image onto a large screen and has devices that tracks the user's position and actions. An example is the CAVE, developed at the Electronic Visualization Laboratory, U. Illinois at Chicago (by Carolina Cruz-Neira and Tom DeFanti). This is a 10x10x10 ft cube with display screens that completely surround the user. The images are projected onto 3 walls and the floor. An advantage of projection systems is that several users may be present, but only one can interact with and manipulate the system.

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Last modified on February 18, 1999, G. Scott Owen,