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Hier finden Sie wissenschaftliche Publikationen aus den FraunhoferInstituten. Methods for efficient sampling of arbitrary distributed volume densities
 Bouatouch, K. ; European Association for Computer Graphics EUROGRAPHICS: Photorealism in computer graphics : Eurographics workshop held in Rennes, France, in June 1990 Berlin: Springer, 1992 (Eurographic Seminars. Tutorials and Perspectives in Computer Graphics) ISBN: 3540542655 ISBN: 0387542655 S.211230 
 Eurographics Workshop on Photosimulation, Realism and Physics in Computer Graphics <1, 1990, Rennes> 

 Englisch 
 Konferenzbeitrag 
 Fraunhofer IGD () 
 Monte Carlo technique; rendering; sampling; solid texturing; volume densities 
Abstract
In recent years a number of techniques have been developed for rendering volume effects (haze, fog, smoke, clouds, etc.). Such techniques have been implemented for projective scanline renderers, raytracers and for radiosity. Roughly speaking, such a method depends on an illumination model which accounts for the lightmaterial interaction, together with a sampling strategy for reading the data of the density field.
The illumination models proposed in literature are quite complicated and require several timeconsuming operations, such as exponential functions, roots and trigonometrical functions. Raytracing and radiosity evaluate the illumination model at every voxel of the density field. Since several hundred complicated calculations are necessary for each ray, such a rigorous evaluation is very timeconsuming. On the other hand, methods proposed for scanline renderes solve the equations describing scattering and reflection of light analytically along each ray within a volume; thus, such methods do not account for arbitrary density distribution.
The purpose of this paper is not to propose a new illumination model, but to compare several methods for efficiently sampling arbitrary distributed data, i.e. , efficiently distribute the samples within the sampling volume. We propose that several sampling strategies can be used to reduce the number of evaluations of the illumination calculations along a ray and, thus, reduce the rendering time needed. Such methods are well suited for scanline renderers but can be used with raytracers. We propose a MonteCarlo approach and an approximative method with useradjustable accuracy to sample the volume data.