Erzeugung von Festkörpermodellen mit dem Spannverfahren unter Anwendung von Würfelteilung

摘要

A span processor receives volumetric data from an imaging apparatus and stores the data as a condensed display list in a span memory. After the volumetric data has been stored, the span processor converts the display list to a display list comprised of points and normal vectors which is stored in a point and normal display list memory. A model clipping circuit determines points which are to be displayed corresponding to desired model cut planes. A rotate circuit transforms the point and normal display list according to the desired orientation, and also converts the normal vectors into levels of shading according to the direction of the normal vector. The points in the transformed display list are clipped to a desired screen viewing region by a screen clipping circuit. A depth buffer, compare circuit, and an AND circuit determine voxels which do not lie behind other surfaces, and are proper to display. The AND circuit allows update of the depth buffer and an image memory buffer, the image memory buffer being a screen map. The image memory is displayed on a monitor. The models are manipulated and cut much more rapidly on a low end workstation than would be possible using conventional methods.