Vision and virtual environments
This chapter is intended to provide the reader with knowledge of the pertinent aspects of human visual processing that are relevant to virtual simulation of various environments. Before considering how real-world vision is simulated, it is perhaps prudent to review the kinds of information that are usually extracted by the visual system. It would, of course, be fruitless to provide visual detail that is rarely or never available to the senses, and it may be fatal to the endeavor to omit detail that is crucial. Thus, an overview of normal visual capabilities and idiosyncrasies is provided in Section 3.2. Section 3.3 reviews some of the ways that perceptual systems provide shortcuts to simulating the visual world. The existence of these phenomena allows system developers to compensate for hardware shortcomings with user inferences. One of the most exciting advantages of virtual environment (VE) technology is that it allows a more elaborate and complex interaction between the VE and the observer. Section 3.4 reviews a number of the ways in which we interact with the world and how these mechanisms might augment and detract from virtual simulation. After the discussion of what vision entails, a discussion of techniques that use 2-D renditions of the visual world to simulate normal viewing of the 3-D world is provided in Section 3.5. The emphasis here will be to address the design requirements of VE displays and to determine if existing displays are machine or observer limited. Considering what is optimally required by the user, a review of the adequacy of existing visual displays is also provided in Section 3.6. Suggestions are made as to how existing limitations might be overcome and speculations are made concerning what new technology might allow in Section 3.7.