Abstract:
This paper presents a technique for color-shading offset surfaces
of CSG models. The offset surfaces are generated by first scan
converting the CSG model into a distance volume. A distance
volume is a volume dataset where the value stored at each voxel is the
shortest distance to the surface of the object being represented by the
volume. Extracting iso-surfaces from the distance volume at various
offset values produces the offset surfaces. The CSG model scan conversion
process also produces closest-point and color volumes. The closest-point
volume contains at each voxel the closest point on the scan converted
CSG model from that voxel location. The color volume contains at each voxel
the associated color on the CSG model at the closest point. During rendering
of the offset surface, the color volume values are used to shade regions
of constant color, and the closest point values are used to supersample
the surface colors of the CSG model in order to anti-alias regions of
changing color.