from
The Free On-line Dictionary of Computing (8 July 2008)
ray casting
<graphics> A simplified form of {ray tracing}. A ray is fired
from each {pixel} in the view plane, and information is
accumulated from all the {voxels} in the volume data it
intersects.
Each voxel is first given an associated colour and opacity.
The ray is sampled at a fixed number of evenly spaced
locations and the colour and opacity are trilinearly
interpolated from the eight nearest voxels. These are then
composed linearly back to front to give a single colour for
the pixel.
Ray casting was invented by John Carmack for the game
{Wolfenstein 3D}. It is faster and lower quality than ray
tracing, and is ideal for interactive applications. It
parallelises well, although random access is needed to the
voxels.
(2004-01-06)