ray tracing

A rendering method that simulates light reflections, refractions and shadows. It follows a light path from a specific source and computes each pixel in the image to simulate the effect of the light. It is a very process-intensive operation. See reflection mapping and radiosity.

Ray-Traced Image
Many of the first graphics simulations were done at the University of Utah, and this is one of them. The shadows in this picture were created by software algorithms that simulate a beam of light from a designated source. (Image courtesy of Computer Sciences Department, University of Utah.)

Modern-day Ray Tracing
This image created in MicroStation Modeler and rendered in the MasterPiece visualization program contains the kinds of realistic shadows and reflections that make a digital object photorealistic. As good as this looks, this picture was reduced to only 256 colors for online and CD-ROM presentation. (Image courtesy of Bentley Systems, Inc.)

The Most Realistic
Although incredibly computation intensive, ray tracing provides the most realistic shadows, reflections and refractions. (Image courtesy of Intergraph Computer Systems.)

(graphics)

ray tracing - 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.

Compare: radiosity.

Usenet newsgroup: news:comp.graphics.raytracing.

http://directory.google.com/Top/Computers/Software/Graphics/3D/Ray_Tracing/.