Diffuse ray tracing
Diffuse ray tracing, also known as stochastic ray tracing or distributed ray tracing , is an algorithm for image synthesis published in 1984 .
Diffuse ray tracing is an extension of normal ray tracing , in which, in certain situations, not just one ray, but several randomly generated rays are used to determine a value. This Monte Carlo simulation can be used to simulate certain “soft” or “blurry” phenomena.
In detail, the following effects can be achieved through diffuse ray tracing:
- Real, soft light shadows (by scanning the visible surface of the light sources)
- Blurred light reflections on shiny surfaces (by distributing the direction of the reflected rays according to the BRDF )
- Depth of field (by scanning the lens surface of the virtual camera system)
- Motion blur (through temporal distribution of the rays during the " exposure time " of a single image )
- Antialiasing of the image (by distributing the rays over the area of the pixels in the image plane)
The nature of the method requires a more or less high number of beams in order to generate low-noise images.
Diffuse ray tracing makes it possible to increase the quality of the image and to take certain effects into account, but diffuse ray tracing does not in itself allow the calculation of global lighting , since secondary rays are only emitted for reflective or shiny surfaces, but not for diffuse surfaces. For this purpose, methods such as path tracing , photon mapping or extended forms of radiosity were developed.
literature
- Robert Cook, Thomas Porter, Loren Carpenter: Distributed ray tracing. In: Hank Christiansen (Ed.): SIGGRAPH '84. 11th annual conference on computer graphics and interactive techniques, Minneapolis, July 1984, proceedings (= Computer Graphics. Vol. 18, No. 3). ACM, New York NY 1984, ISBN 0-89791-138-5 , pp. 137-145, doi: 10.1145 / 800031.808590 .