The Alchemy Screen-Space Ambient Obscurance Algorithm

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dc.contributor.authorMcGuire, Morganen_US
dc.contributor.authorOsman, Brianen_US
dc.contributor.authorBukowski, Michaelen_US
dc.contributor.authorHennessy, Padraicen_US
dc.contributor.editorCarsten Dachsbacher and William Mark and Jacopo Pantaleonien_US
dc.date.accessioned2016-02-18T11:01:47Z
dc.date.available2016-02-18T11:01:47Z
dc.date.issued2011en_US
dc.description.abstractAmbient obscurance (AO) produces perceptually important illumination effects such as darkened corners, cracks, and wrinkles; proximity darkening; and contact shadows. We present the AO algorithm from the Alchemy engine used at Vicarious Visions in commercialgames. It is based on a new derivation of screen-space obscurance for robustness, and the insight that a falloff function can cancel terms in a visibility integral to favor efficient operations. Alchemy creates contact shadows that conform to surfaces, capturesobscurance from geometry of varying scale, and provides four intuitive appearance parameters: world-space radius and bias, and aesthetic intensity and contrast. The algorithm estimates obscurance at a pixel from sample points read from depth and normal buffers. It processes dynamic scenes at HD 720p resolution in about 4.5 ms on Xbox 360 and 3 ms onNVIDIA GeForce580.en_US
dc.description.sectionheadersApproximate Global Illuminationen_US
dc.description.seriesinformationEurographics/ ACM SIGGRAPH Symposium on High Performance Graphicsen_US
dc.identifier.doi10.1145/2018323.2018327en_US
dc.identifier.isbn978-1-4503-0896-0en_US
dc.identifier.issn2079-8687en_US
dc.identifier.pages25-32en_US
dc.identifier.urihttps://doi.org/10.1145/2018323.2018327en_US
dc.publisherACMen_US
dc.subjectI.3.3 [Picture/Image Generation]en_US
dc.subjectDisplay Algorithmsen_US
dc.subjectI.3.7 [Three Dimensional Graphics and Realism]en_US
dc.subjectColoren_US
dc.subjectshadingen_US
dc.subjectshadowingen_US
dc.subjectand textureen_US
dc.subjectambient occlusionen_US
dc.subjectambient obscuranceen_US
dc.subjectscreen spaceen_US
dc.titleThe Alchemy Screen-Space Ambient Obscurance Algorithmen_US
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High-Performance Graphics 2011