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Bidirectional Importance Sampling for Unstructured Direct Illumination
University of Massachusetts.
Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
2009 (English)In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 28, no 2, 269-278 p.Article in journal (Refereed) Published
Abstract [en]

Recent research in bidirectional importance sampling has focused primarily on structured illumination sources such as distant environment maps, while unstructured illumination has received little attention. In this paper, we present a method for bidirectional importance sampling of unstructured illumination, allowing us to use the same method for sampling both distant as well as local/indirect sources. Building upon recent work in [WFA*05], we model complex illumination as a large set of point lights. The subsequent sampling process draws samples only from this point set. We start by constructing a piecewise constant approximation for the lighting using an illumination cut [CPWAP08]. We show that this cut can be used directly for illumination importance sampling. We then use BRDF importance sampling followed by sample counting to update the cut, resulting in a bidirectional distribution that closely approximates the product of the illumination and BRDF. Drawing visibility samples from this new distribution significantly reduces the sampling variance. As a main advance over previous work, our method allows for unstructured sources, including arbitrary local direct lighting and one-bounce of indirect lighting.

Place, publisher, year, edition, pages
Blackwell Publishing Ltd , 2009. Vol. 28, no 2, 269-278 p.
Keyword [en]
Computer Graphics [I.3.7]: Three-Dimensional Graphics and Realism; Raytracing
National Category
Medical and Health Sciences
URN: urn:nbn:se:liu:diva-55093DOI: 10.1111/j.1467-8659.2009.01366.xISI: 000264544700012OAI: diva2:315346
Available from: 2010-04-29 Created: 2010-04-29 Last updated: 2010-04-29

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