A CUBIC TETRAHEDRAL ADAPTATION OF THE HEMI-CUBE ALGORITHM

Publisher Summary This chapter discusses cubic tetrahedral adaptation of the hemi-cube algorithm. The hemi-cube algorithm has become the most popular method of calculating radiosity solutions for complex environments containing hidden surfaces and shadows. A cubic tetrahedral adaptation of this algorithm increases performance by reducing the number of projection planes from five to three, while maintaining the simplicity of the required clipping and projection operations. The hemi-cube algorithm calculates the amount of light landing on a patch from every other patch by transforming the environment so that the receiving patch's center is at the origin and its normal coincides with the positive z axis. An imaginary cube is constructed around the center of the receiving patch. The upper half of this cube provides four half-faces and one full face onto which the environment is projected. Each of these faces is divided into square pixels at a given resolution. The hemi-cube is illustrated in the chapter. An advantage of the cubic tetrahedral adaptation is the fact that each of the faces is identical. The hemi-cube uses four half-faces and one full face of a cube, thus requiring the top face to be treated differently than the four side faces.