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 orthogonal cartesian grids, but in the last years research did also concentrate on arbitrary structured or even unstructured topologies. In particular, direct volume rendering of these data types is numerically complex and mostly requires sorting the whole data base. In this paper we present a new approach to direct rendering of convex, voluminous polyhedra on arbitrary grid topologies, which efficiently use hardware assisted polygon drawing to support the sorting procedure. 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 order and the volume integration is performed. Thus, the complexity of the sorting procedure is reduced. Furthermore, any connectivity information can be completely neglected, which allows for the rendering of arbitrary scattered, convex polyhedra.