CAVE Automatic Virtual Environment

CAVE Overview

Virtual reality may best be defined as the wide-field presentation of computer-generated, multi-sensory information which tracks a user in real time. In addition to the more well-known modes of virtual reality - head-mounted displays and binocular omni-oriented monitor (BOOM) displays - the Electronic Visualization Laboratory at the University of Illinois at Chicago introduced a third mode in 1992: a room constructed of large screens on which the graphics are projected onto two to three walls and/or the floor.

The CAVE is a multi-person, room-sized, high-resolution, 3D video and audio environment. In the current configuration, graphics are rear projected in stereo onto two walls and the floor, and viewed with stereo glasses. As a viewer wearing a location sensor moves within its display boundaries, the correct perspective and stereo projections of the environment are updated, and the image moves with and surrounds the viewer. The other viewers in the CAVE are like passengers in a bus, along for the ride!

Specifically, the CAVE is a theater 10x10x9 feet, made up of two rear-projection screens for walls and a down-projection screen for the floor. Electrohome Marquis 8000 projectors throw full-color workstation fields (1024x768 stereo) at 96 Hz onto the screens, giving approximately 2,000 linear pixel resolution to the surrounding composite image. Computer-controlled audio provides a sonification capability to multiple speakers. A user's head and hand are tracked with Ascension tethered electromagnetic sensors. Stereographics' LCD stereo shutter glasses are used to separate the alternate fields going to the eyes. A Silicon Graphics Onyx with three Reality Engines is used to create the imagery that is projected onto the walls and floor. The CAVE's theater area sits in a 30x20x13-foot light-tight room, provided that the projectors' optics are folded by mirrors.

Goals that inspired the CAVE engineering effort include:

The desire for higher-resolution color images and good surround vision without geometric distortion
Less sensitivity to head-rotation induced errors
The ability to mix virtual reality imagery with real devices (like one's hand, for instance)
The need to guide and teach others in a reasonable way in artificial worlds
The desire to couple to networked supercomputers and data sources for successive refinement

"CAVE," the name selected for the virtual reality theater, is both a recursive acronym (Cave Automatic Virtual Environment) and a reference to "The Simile of the Cave" found in Plato's Republic, in which the philosopher explores the ideas of perception, reality, and illusion. Plato used the analogy of a person facing the back of a cave alive with shadows that are his/her only basis for ideas of what real objects are.

The CAVE premiered at the ACM SIGGRAPH 92 conference. It is achieving national recognition as an excellent virtual reality prototype and a compelling display environment for computational science and engineering data.