The VSBUFFER: visibility ordering of unstructured volume primitives by polygon drawing

Different techniques have been proposed for rendering volumetric scalar data sets. Usually these approaches are focusing on o rthog- onal cartesian grids, but in the last years research did also concen- trate on arbitrary structured or even unstructured topolog ies. In par- ticular, direct volume rendering of these data types is nume rically complex and mostly requires sorting the whole data base. In this paper we present a new approach to direct rendering of convex, vo- luminous polyhedra on arbitrary grid topologies, which effi ciently use hardware assisted polygon drawing to support the sorting pro- cedure. The key idea of this technique lies in a two-pass rendering approach. First, the volume primitives are drawn in polygon mode to obtain their cross-sections in the VSBUFFER orthogonal to the viewing plane. Second, this buffer is traversed in front-to -back or- der and the volume integration is performed. Thus, the complexity of the sorting procedure is reduced. Furthermore, any conne ctiv- ity information can be completely neglected, which allows for the rendering of arbitrary scattered, convex polyhedra.