PART I : General Issues in the Design and Use of Virtual and Adaptive Environments Visual Perception Egocentric ~ istance in Real and Virtual Environments

Even after decades of research, visual space perception remains the subject of active investigation, indicating that it is indeed a challenging problem. Even at a functional level, we are still far from fully understanding some fundamental issues, such as the mapping between physical and visual space (visually perceived space), the connection between visual space and action, and which aspects of visual stimulation are most important in determining the structure of visual space. In the absence of a functional-level understanding, it is hardly surprising that our understanding of the underlying physiological mechanisms lags further behind. Nowhere is our lack of understanding more apparent than when one attempts to synthesize realistic virtual environments using computer graphics; most challenging in this regard is making large-scale vistas and structures appear as immense as their real-world counterparts.