The Free On-line Dictionary of Computing (30 December 2018):
A technique used in computer graphics to create
realistic images by calculating the paths taken by rays of
light entering the observer's eye at different angles. The
paths are traced backward from the viewpoint, through a point
(a pixel) in the image plane until they hit some object in
the scene or go off to infinity. Objects are modelled as
collections of abutting surfaces which may be rectangles,
triangles, or more complicated shapes such as 3D splines.
The optical properties of different surfaces (colour,
reflectance, transmitance, refraction, texture) also affect
how it will contribute to the colour and brightness of the
ray. The position, colour, and brightness of light sources,
including ambient lighting, is also taken into account.
Ray tracing is an ideal application for parallel processing
since there are many pixels, each of whose values is
independent and can thus be calculated in parallel.
Usenet newsgroup: news:comp.graphics.raytracing.