Efficient Volume Rendering by IsoRegion Leaping Acceleration

This paper introduces a new acceleration technique for ray casting type volume rendering called IsoRegion Leaping. A factorization of the sample composition equation leads to our new algorithm which is based on homogeneity inside a volume. We create an IsoRegion data structure to help identifying homogeneous voxel cubes, which is independent of the viewing parameters and shading conditions, thus can be pre-processed. Accumulated colors and transparencies of homogeneous ray segments are pre-computed into a look-up table according to different voxel values and ray segment lengths. Attributes of ray segments piercing through IsoRegion blocks are looked-up from the table. Therefore, unnecessary sample compositions within IsoRegions are saved. This voxel leaping technique is experimentally proved to be efficient even for real-life medical volume data. A speedup of 2 to 3 times is measured while preserving the image quality. Images generated by our algorithm and the ones from the original algorithm without IsoRegion Leaping acceleration are identical, both theoretically