To move beyond the current generation of graphics screen and mouse, to transport the user through the screen into the computer, we need hardware and software that provide the user a three dimensional simulacrum of a world and allows interaction in ways that mimic interaction with real world objects. Several terms have been used to refer to a computer-simulated world, none particularly attractive. ``Artificial reality'' and ``virtual reality'' are oxymorons, Ted Nelson's term ``virtuality'' refers to a much more general class of computer worlds, ``world simulator'' is too grandiose for what we're talking about, and ``cyberspace'' misuses the root ``cyber'' (from --``steersman'') to denote computer rather than control. Nonetheless, I will use ``cyberspace'' here to avoid burdening the discourse with still another term. Since I'm talking about means of man/machine interaction, I can make the case that ``cyberspace'' means a three dimensional domain in which cybernetic feedback and control occur.
I define a cyberspace system as one which provides the user a three-dimensional interaction experience that provides the illusion he is inside a world rather than observing an image. At the minimum, a cyberspace system provides stereoscopic imagery of three dimensional objects, sensing the user's head position and rapidly updating the perceived scene. In addition, a cyberspace system provides a means of interacting with simulated objects. The richness and fidelity of a cyberspace system can be extended by providing better three dimensional imagery, sensing the user's pupil direction, providing motion cues and force feedback, generating sound from simulated sources, and further approximating reality almost without bounds (wind in the face, odor, temperature-direct neural interface, anyone?).
The idea of transporting the user in some fashion into a computer and allowing him to interact directly with a virtual world has been extensively explored in science fiction. Frederick Pohl's later Heechee books (the second of which, Beyond the Blue Event Horizon, inspired the product Autodesk, which idea played a significant part in the formation of this company), writers of the ``cyberpunk'' genre such as William Gibson and Rudy Rucker, and movies including even Tron have explored what we will find and what we will become when we enter these worlds of our own creation. It's no wonder the idea of entering a computer world is so fascinating--it can be thought of as the ultimate realisation of what fiction has been striving for since sagas of the hunt were told around Paleolithic campfires. The images that prose and poetry create in the mind, that the theatre enacts on stage, that motion pictures and television (aided by special effects) bring to millions can, inside a computer, not only be given three-dimensional substance, but can interact directly with the viewer, now a participant rather than passive spectator.
Science fiction's attention to the idea of entering a computer world should not be taken as an indication that the idea is itself infeasible, part of the distant future, or a fictional device devoid of practical applications. Ivan Sutherland, who invented so much of what we now consider commonplace in the computer graphics industry, realised in the 1960's that using two small CRTs to provide stereoscopic images to the eyes and sensing head position to compute the viewpoint was the way to three dimensional realism. In 1968 Sutherland built a helmet with two CRTs, attached to the ceiling with a set of linkages and shaft encoders to determine head position. This contraption, called the ``Sword of Damocles'' because of all the hardware dangling above the user's cranial vault, really had only one serious flaw--it was twenty years ahead of its time in the computer power required to make it practical.
Now that fast CPUs and special-purpose graphics hardware have made real-time generation of realistic 3D images widely available at reasonable cost, and every expectation is that the ongoing trend of increasing performance at decreasing cost will soon bring that power to personal computers, the technological groundwork is in place to bring Sutherland's prototype into the mainstream of computer graphics. Interest in head mounted displays and other cyberspace technologies is growing. Attached to this paper are an article from the October 1987 Scientific American titled ``Interfaces for Advanced Computing'' which surveys the field and describes current technology, a paper titled ``Virtual Environment Display System'' by the group at NASA Ames who built the first modern cyberspace system, an article from the August 15th, 1988 Aviation Week and Space Technology describing a helmet-mounted display with head tracking being tested by Navy aviators, and an article from the August 22nd issue of the Independent Journal which indicates that the potential of cyberspace is beginning to filter down to even minor suburban dailies.
Editor: John Walker