CAVE

The CAVE (a recursive acronym for CAVE Automatic Virtual Environment) was developed in 1991 by Daniel Sandin and Thomas DeFanti at the University of Illinois at Chicago (UIC). It is an immersive virtual reality display device used for art, scientific visualization, and collaboration.

Sandin, who joined UIC's faculty in 1969, and DeFanti, who was hired there in 1972, were active in merging technology and art in the 1970s and 1980s. Their work initially focused on video art, and later on the use of personal computers for art, education, and scientific visualization. The pair co-founded the Electronic Visualization Lab (EVL) at UIC, and created an environment in which faculty and students from many disciplines (primarily engineering and art, but also mathematics, communication, and psychology, among others) could work together on virtual reality and computer networking projects. In 1991, the pair conceived of a virtual reality “theater”—a room, approximately 10 feet on each side, that people could enter. EVL students Carolina Cruz-Neira, Greg Dawe, Sumit Das, and others helped realize their conception by building hardware and software components. The CAVE was premiered at the 1992 conference of the Association of Computing Machinery Special Interest Group on Computer Graphics and Interactive Techniques (ACM SIGGRAPH) in Chicago.

Electronic Visualization Lab student Marcus Thiébaux demonstrates the CAVE. (Courtesy of National Center for Supercomputing Applications)

The acronym CAVE was chosen in part because of its allusion to Plato's “The Allegory of the Cave.” Plato describes a cave occupied by a group of people. They can see only its rear wall and the shadows cast on it from the cave's entrance. The cave's occupants therefore believe that the shadows are reality.

Unlike the users of many virtual reality systems developed in the 1980s and 1990s, CAVE users occupy a room-like space, rather than wearing head-mounted displays or helmets. (However, they do don a pair of glasses similar to the safety goggles used in woodworking shops or chemistry labs.) Since more than one user can be in a CAVE, rather than being individually isolated, as is the case with head-mounted displays or helmets, the CAVE is a multi-person environment.

Using rear-projection, stereo perspective-corrected images can be displayed on all sides of the CAVE. Users' CAVE glasses are synchronized to the images being displayed. The glasses' lenses are made of liquid crystal display shutters that separate the stereo [Page 62]images, ensuring that each eye sees only one of the stereo images at a time. As a result, the images appear to the CAVE's occupants to be three-dimensional. They appear to extend into the room, away from and around the viewer. Currently, prototypes exist that make the glasses appear to be little more than classic “Ray-Ban” sunglasses. Research is being undertaken to do away with the glasses altogether.

The CAVE's success at creating 3-D virtual reality is based on Sandin and DeFanti's understanding of optics and perception. They knew that parallax, the different perspectives presented to each eye in binocular vision, depth occlusion, and other visual information are combined in the brain to produce knowledge of the depth of what a person sees. As a result, they were able to create hardware and software that creates a sufficiently information-rich illusion to assist the brain in decoding the CAVE's images as three-dimensional.

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