Image space graphics
Richard Kiesenfeld, Lance Williams · 2000
This dissertation consists of three papers: Casting Curved Shadows on Curved Surfaces (1978), Pyramidal Parametrics (1983), and View Interpolation for Image Synthesis (1993). (1) Shadowing has historically been used to increase the intelligibility of scenes in electron microscopy and aerial survey. Various methods have been published for shadows in computer synthesized scenes. The display of shadows may make the shape and relative position of objects in such scenes more comprehensible; it is a technique lending vividness and realism to computer animation. In order to attain good results, the discrete nature of the visible-surface computations must be treated with care. The effects of dither, interpolation, and geometric quantization of the shadowing algorithm are examined. This paper describes one of the first applications of “jitter sampling” in computer graphics. (2) The mapping of images onto surfaces may substantially increase the realism and information content of computer-generated imagery. As the projected scale of the surface increases, interpolation between the original samples of the source image is necessary; as the scale is reduced, approximation of multiple samples in the source is required. Thus a constantly changing sampling window of view-dependent shape must traverse the source image. Although the mapping of texture onto surfaces is an excellent example of the process and provided the original motivation for its development, pyramidal parametric data structures admit of wider application. The aliasing of not only surface texture, but also highlights and even the surface representations themselves, may be minimized by pyramidal parametric means. (3) Texture mapping has been used to provide a means for images to be used as display primitives. This paper endeavors to carry this concept to its logical extreme by using interpolated images to portray three-dimensional (3D) scenes. View interpolation to synthesize 3D scenes has two main advantages. First, the 3D representation of the scene may be replaced with images. Second, the image synthesis time is independent of the scene complexity. Potential applications of the method include virtual holograms, a walkthrough in a virtual environment, image-based primitives and incremental rendering.