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Sampling Projected Spherical Caps in Real Time

Peters, Christoph; Dachsbacher, Carsten

Abstract (englisch):
Stochastic shading with area lights requires methods to sample the light sources. For diffuse materials, the best strategy is to sample proportionally to projected solid angle. Recent work in offline rendering has addressed this problem for spherical light sources, but the solution is unsuitable for a GPU implementation. We present a far more efficient solution. It offers results without noteworthy noise for diffuse surfaces lit by an unoccluded spherical light source while being only two to three times more costly than simple sampling of the solid angle. The core insight of the technique is that a projected spherical cap can be decomposed into, or at least approximated by, cut disks. We present an efficient method to sample cut disks and show how to use it to sample projected spherical caps. In some cases, our method does not sample exactly proportionally to projected solid angle but the deviation is provably bounded.

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Postprint §
DOI: 10.5445/IR/1000119985
Veröffentlicht am 17.06.2020
DOI: 10.1145/3320282
Zitationen: 5
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Visualisierung und Datenanalyse (IVD)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 06.2019
Sprache Englisch
Identifikator ISSN: 2577-6193
KITopen-ID: 1000119985
Erschienen in Proceedings of the ACM on Computer Graphics and Interactive Techniques
Band 2
Heft 1
Seiten 1.1 - 1.16
Bemerkung zur Veröffentlichung Artikel-Nr.1
Vorab online veröffentlicht am 31.05.2019
Schlagwörter sampling, projected spherical caps, spherical light sources, area lights, diffuse shading, real-time shadows, ray traced soft shadows
Nachgewiesen in Dimensions
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