Cell projection of convex polyhedra

Finite element methods commonly use unstructured grids as the computational domain. As a matter of fact, the volume visualization of these unstructured grids is a time consuming task. Here, the fastest known object order algorithm is the projected tetrahedra algorithm of Shirley and Tuchman. Even with the upcoming of programmable graphics hardware, the rendering performance did not keep up with the growing complexity of the simulation data. In this paper we strive to improve the performance of the cell projection technique by posing several restrictions on the optical model. This allows us to devise a simple but fast hardware-accelerated algorithm which is able to project arbitrary polyhedral cells, that is tetrahedra, prisms, hexahedra, etc. For this reason, our algorithm is well suited for the display of unstructured FEM meshes with mixed cell types, but it is also applicable to the real-time display of gaseous phenonema, such as fire and ground fog.