What does virtual reality need?: human factors issues in the design of three-dimensional computer environments

Virtual reality (VR) has invaded the public's awareness through a series of media articles that have promoted it as a new and exciting form of computer interaction. We discuss the extent to which VR may be a useful tool in visualization and attempt to disambiguate the use of VR as a general descriptor for any three-dimensional computer presentation. The argument is presented that, to warrant the use of the term virtual environment (VE), the display should satisfy criteria that arise from the nature of human spatial perception. It directly follows, therefore, that perceptual criteria are the foundations of an effective VE display. We address the task of making a VE system easy to navigate, traverse and engage, by examining the ways in which three-dimensional perception and perception of motion may be supported, and consider the potential conflict that may arise between depth cues. We propose that the design of VE systems must centre on the perceptual-motor capabilities of the user, in the context of the task to be undertaken, and establish what is essential, desirable and optimal in order to maximize the task gains, while minimizing the learning required to operate within three-dimensional interactive displays.