Like many seminal notions, "virtual reality" eludes definition at first — but we know it when we see it! At LEEP Systems we think of it, for now any way, as a brand new medium — the most versatile medium ever conceived.

The single most important ingredient of virtual reality is the sense of inhabiting another space. So, because the human sensorium is dominantly visual, the dominant implement of this new medium is the very wide angle stereoscopic display, which , as NASA puts it, "immerses the user" in a virtual space. The head mount and head position sensor enable a full spherical view of the computer-generated, or of the remote, virtual world.

And we would make a special point of that last duality: the virtual world can be computer-generated, hence "artificial"; it can also be perfectly real, but remote. In fact it is the remote virtual realities, the hazardous waste spaces, the landscape of Mars, the ocean deeps, the vacuum outside the space station, the cross-continental surgery, the intra-arterial excavation, the mines and oil wells and sewers — all the places it may be useful but dangerous or impossible to go — that will provide the first gainful employment for virtual reality. LEEP Systems provides standard commercial sight and sound systems for experiment in these regions, and we will soon have dual resolution systems that will enable exacting work at a distance.

The other kind of virtual reality, the artificial, computed space, is the one that inspires the press, partly because it tells of another way of dealing with computers as such, and partly because it conjures worlds that are not constrained by mundane matters like physics and realizable materials. Here the returns will be slower — because it is hard for an affordable computer to calculate and paint complex spaces as fast as video cameras can see them. Surely entertainment will be the first major beneficiary of this side of this new medium, for it demands less verisimilitude — of shapes, colors, sounds or time. Fantastic is good enough.

Note that the "sense" of inhabiting another space does not mean fooling the eye. For the foreseeable future there will be no technology allowing the user to mistake the visual virtual world for a real world, but this is no more a handicap for virtual reality than it is for television or cinema; it is easy for the explorer to suspend disbelief and function effectively, or to be delightfully beguiled. Rather than wasting computing power and channel capacity on spurious detail, the authors (or reporters) of virtual worlds will spend their assets usefully. The images are good enough for entertainment now, and by the simple introduction of high resolution area-of-interest inserts, they can be made good enough to do serious work. Whether anyone will ever actually be fooled doesn't matter.

The near future holds dramatic improvements, though, in the tools and equipment of virtual reality, in the peripherals that permit useful work through massive and precise interaction with the human. With the refinement of these peripherals, we will see virtual reality come into its own.