Virtual environments and environmental instruments

1.1 Virtual environments are media Virtual environments created through computer graphics are communications media (Licklider , 1978). They have both physical and abstract components like other media. Paper, for example, is a communication medium but the paper is itself only one possible physical embodiment of the abstraction of a two-dimensional surface onto which marks may be made. Consequently, there are alternative instantiations of the same abstraction. As an alternative to paper, for example, the Apple Newton series of intelligent information appliances resemble handwriting-recognizing magic slates on which users write commands and data with a stylus (see Apple Computer Co., 1992). The corresponding abstraction for head-coupled, virtual image, stereoscopic displays that synthesize a coordinated sensory experience is an environment. Recent advances and cost reductions in the underlying technology used to create virtual environments have made possible the development of new interactive systems that can subjectively displace their users to real or imaginary remote locations. et al. Different expressions have been used to describe these synthetic experiences. Terms like "virtual world" or "virtual environment" seem preferable since they are linguistically conservative, less subject to journalistic hyperbole and easily related to well-established usage as in the term "virtual image" of geometric optics. These so called "virtual reality" media several years ago caught the international public imagination as a qualitatively new human-machine interface Because of this history, it is important to ask why displays of this sort have only recently captured public attention. The reason for the recent attention stems mainly from a change in the perception of the accessibility of the technology. Though its roots, as discussed below, can be traced to the beginnings of flight simulation and telerobotics displays, recent drops in the cost of interactive 3D graphics systems and miniature video displays have made it realistic to consider a wide variety of new applications for virtual environment displays. Furthermore, many video demonstrations in the mid-1980's gave the impression that indeed this interactive technology was ready to go. In fact, at that time, considerable development was needed before it could be practicable and these design needs still persist for many applications. Nevertheless, virtual environments can indeed become Ivan Sutherland's "ultimate computer display"; but in order to insure that they provide effective communications channels between their human users and their underlying environmental simulations, they must be designed. A well designed human-machine interface affords the user an efficient and effortless flow of information between …