Selectively meshed surface representation

Surface rendering is an important technique for volume visualization. Any surface rendering algorithm has two phases surface generation and rendering. We present a new surface rendering algorithm, which focuses on constructing the surface in a manner that speeds up the rendering phase. The motivation behind this is to reduce the response time for surface manipulations such as interactive rotations. We utilize a MC-like (Marching Cubes) approach to calculate the intersection points and their normals for each cube. But we dynamically link the intersection points to form triangles within the cube according to the locations of the last and the next visited neighboring cubes so that a good meshed surface can be generated. The difficulty with such an approach is that thousands of special cases need to be considered. But, we have found that the occurrence of 5 specific configurations out of the 14 basic MC cube configurations account for over 95% of all the cubes intersected by the iso-surface in most data sets. We process cubes belonging to these 5 configurations in a mesh mode, and the rest are processed in a non-mesh mode. As a result, the number of special cases are reduced substantially. Then a very careful analysis of the 5 configurations for mesh processing leads to just 136 cases, which makes the algorithm very simple. Test results show that the rendering time is almost halved compared to the time required for the rendering of a nonmeshed surface generated by MC.