Accurate Computation of Single Scattering in Participating Media with Refractive Boundaries

• Published in: Computer graphics forum Vol. 34; no. 6; pp. 48 - 59
• Main Author: Holzschuch, N.
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01.09.2015; Wiley
• Subjects: Algorithms; Analysis; Cameras; Categories and Subject Descriptors (according to ACM CCS)): I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism.Colour; Categories and Subject Descriptors (according to ACM CCS)): I.3.7 [Computer Graphics]: Three‐Dimensional Graphics and Realism.Colour, shading, shadowing and texture; Computation; Computer Science; Federations; Focusing; Graphics; illumination rendering; Image processing systems; Media; Opacity; Radiance; Refraction; rendering; Scattering; shading; shadowing and texture; Studies; volume rendering; shading; participating media; shadowing and texture
• ISSN: 0167-7055; 1467-8659
• DOI: 10.1111/cgf.12517

Volume caustics are high‐frequency effects appearing in participating media with low opacity, when refractive interfaces are focusing the light rays. Refractions make them hard to compute, since screen locality does not correlate with spatial locality in the medium. In this paper, we give a new method for accurate computation of single scattering effects in a participating media enclosed by refractive interfaces. Our algorithm is based on the observation that although radiance along each camera ray is irregular, contributions from individual triangles are smooth. Our method gives more accurate results than existing methods, faster. It uses minimal information and requires no pre‐computation or additional data structures. Volume caustics are high‐frequency effects appearing in participating media with low opacity, when refractive interfaces are focusing the light rays. Refractions make them hard to compute, since screen locality does not correlate with spatial locality in the medium. In this paper, we give a new method for accurate computation of single scattering effects in a participating media enclosed by refractive interfaces. Our algorithm is based on the observation that although radiance along each camera ray is irregular, contributions from individual triangles are smooth. Our method gives more accurate results than existing methods, faster. It uses minimal information and requires no pre‐computation or additional data structures.