title: Accurate direct illumination using iterative adaptive sampling.
abstract: This paper introduces a new multipass algorithm for efficiently computing direct illumination in scenes with many lights and complex occlusion. Images are first divided into 8 x 8 pixel blocks and for each point to be shaded within a block, a probability density function (PDF) is constructed over the lights and sampled to estimate illumination using a small number of shadow rays. Information from these samples is then aggregated at both the pixel and block level and used to optimize the PDFs for the next pass. Over multiple passes the PDFs and pixel estimates are updated until convergence. Using aggregation and feedback progressively improves the sampling and automatically exploits both visibility and spatial coherence. We also use novel extensions for efficient antialiasing. Our adaptive multipass approach computes accurate direct illumination eight times faster than prior approaches in tests on several complex scenes.
authors.affiliation: 53d Test Support Squadron, Tyndall Air Force Base, FL 32403, USA. mike@graphics.cornell.edu
authors.forename: Michael
authors.initials: M
authors.lastname: Donikian
authors.forename: Bruce
authors.initials: B
authors.lastname: Walter
authors.forename: Kavita
authors.initials: K
authors.lastname: Bala
authors.forename: Sebastian
authors.initials: S
authors.lastname: Fernandez
authors.forename: Donald P
authors.initials: DP
authors.lastname: Greenberg
mesh_terms: D000465:Algorithms; D003196:Computer Graphics; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods; D008027:Light; D008029:Lighting; D010783:Photometry / Q000379:methods; D015203:Reproducibility of Results; D018401:Sample Size; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D014584:User-Computer Interface