Visual Modality in Virtual Reality
Sight is perhaps the most important of all human senses, and the visual modality is thus also a key component of virtual reality. This chapter begins with the biological basics of human visual perception, with a particular focus on depth perception. It then explores the basic elements of computer graphics. It describes the basic models used in virtual environments (polygons, implicit and parametric surfaces, constructive solid geometry, solid modeling) as well as the process of rendering a model (via projections and transformations, clipping, determining visible objects, illumination, and finally pixel conversion). The chapter concludes with a description of various visual displays, from two-dimensional liquid crystal and plasma systems to stereoscopic displays such as head-mounted, spatially multiplexed, temporally multiplexed and volumetric displays.