Fast projective volume rendering: approximating the rendering process or simplifying the data ?

How to render very complex datasets, and yet maintain interactive response times, is a hot topic in volume rendering. In this paper we focus on projective visualization of datasets represented via tetrahedral tessellations. Direct projective visualization is performed by sorting tetrahedra with respect to view direction and then by projecting them onto the screen. Different sorting algorythms and "per tetrahedra" projection techniques are reviewed and evaluated. anew method fot tetrahedra projection approximation is presented. In addiction, we compare the results obtained by the optimization of rendering process with those obtained by adopting a data simplification approach