Graphics Reference
In-Depth Information
Figure 3.5
Volume rendering technique presented by Robert A. Drebin, Loren Carpenter, and Pat
Hanrahan. (From [Drebin et al. 88] c
1988 ACM, Inc. Included here by permission.)
as a collection of polygons or other surface primitives. The marching cubes al-
gorithm has trouble reconstructing a surface with fine detail because of the huge
number of polygons needed. Furthermore, connectivity issues arise when surfaces
have too many branches.
The method described in the “Volume Rendering” paper assumes that several
substances are mixed in a voxel. In human CT data these substances are air, soft
tissue, fat, and bone. The first step is to compute the percentage of each material
in each voxel, then a voxel density is computed from the product of the physical
