A hidden surface removal system is described that generates a three-space description of an input scene. The system acts upon objects modelled as non.penetrating, 3D, triangular flat-plates. The process uses 'boundary traversal' algorithms to replace each partially obscured surface with a set of triangular surfaces that comprise its visible portions. The process is particularly relevant to analytic modelling applications.
Hidden-surface, graphics, boundary troversal, geometric analysis, flat plate, analytic modelling
The pervasive application of computer graphics to aid design and modelling efforts has stimulated interest in the problems of hidden surface removal. Since the primary goal of many researchers has been the generation of realistic displays, it is not surprising that the most popular approaches to hidden surface removal have involved a fundamental integration of hidden surface removal and graphics display generation. Most approaches 'remove' hidden surfaces by overlaying them with visible oortions of the scene to be displayed. The approach described in this paper, however, is predicated upon redefining each partially hidden surface as a collection of entirely visible surfaces.
This approach involves examining two surfaces at a time. Boundary traversal techniques are used when one of the surfaces partially obscures the other. The contours of the partly hiaden surface's visible portions are obtained by traversing the contours of the two surfaces in an appropriate manner.
The boundary traversal approach was developed to support signal-return modelling. This application is perspective dependent, for it models the signal-return from each surface in a scene that is 'visible' to the signal-receiving instrumentation. The instrument's location in three-space defines the viewpoint from which a modelled object will be studied. A 3D description of each unobscured surface is necessary for the requisite mathematics that model signal return. The process operates on 3D nonpenetrating, triangular flatplates, described as a counter-clockwise triplet of vertex coordinates.