Voxel Elimination

Most approaches to optimize the performance of MIP rendering aim at excluding voxels from the traversal and rendering process, which contain less-important information like low-valued background noise. In fact, in addition to this low-importance data, there is usually a remarkable amount of regular-valued voxels which never contribute to a MIP image. A voxel $V$ does never contribute to a MIP and can be discarded if all possible rays through the voxel hit another voxel $W$ with $d(W)\geq d(V)$ either before or after passing through $V$, where $d(V)$ is the data value at voxel $V$. This fact can be exploited when original voxel-values are used for rendering using nearest neighbor interpolation, as it is done within the presented approach.

In the following, two algorithms for identifying non-contributing voxels are presented. The first approach performs classification based on the local neighborhood of a voxel, identifying voxels invisible from any viewing direction. The second algorithm groups possible viewing directions into several clusters and produces a set of potentially contributing voxels for each cluster. The view-point dependent elimination achieves much better elimination rates at the cost of storing several sets of voxels for rendering.

mailto:mroz@cg.tuwien.ac.at.