Chapter 13

Introduction The capabilities and limitations of users drive many of the design decisions of virtual environment technology. These considerations affect both the design of the hardware and the design of the software. To be interactive, a VE software application needs to constantly present the current "view" of a computer-generated world, and have that world react quickly to the user's actions. To be convincing, the presentation must provide enough detail to make objects easily recognizable, and enough objects to give the user the sense of being in the world. To be useful, the environment must respond to the user, perhaps by changing a parameter of a visualization or a dimension of an object's design, or by having objects respond as the real objects that they represent would respond. An environment can be described as a geometry, which describes the spatial relationship of objects to the user or users, and the behavior of these objects. Objects may have a visual appearance, may make