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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.<\/jats:p>","DOI":"10.1145\/3320282","type":"journal-article","created":{"date-parts":[[2019,6,4]],"date-time":"2019-06-04T16:01:38Z","timestamp":1559664098000},"page":"1-16","update-policy":"https:\/\/doi.org\/10.1145\/crossmark-policy","source":"Crossref","is-referenced-by-count":9,"title":["Sampling Projected Spherical Caps in Real Time"],"prefix":"10.1145","volume":"2","author":[{"given":"Christoph","family":"Peters","sequence":"first","affiliation":[{"name":"Karlsruhe Institute of Technology, Karlsruhe, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Carsten","family":"Dachsbacher","sequence":"additional","affiliation":[{"name":"Karlsruhe Institute of Technology, Karlsruhe, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"320","published-online":{"date-parts":[[2019,6,3]]},"reference":[{"doi-asserted-by":"publisher","key":"e_1_2_2_1_1","DOI":"10.1145\/218380.218500"},{"key":"e_1_2_2_2_1","volume-title":"The Falcor Rendering Framework 3.2. 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(March 1996), 30 pages. https:\/\/www.microsoft.com\/en-us\/research\/publication\/area-light-sources-for-real-time-graphics\/ Microsoft technical report MSR-TR-96-11."},{"key":"e_1_2_2_15_1","volume-title":"Proc. SPIE","author":"Ulichney Robert A.","year":"1993","unstructured":"Robert A. Ulichney . 1993 . Void-and-cluster method for dither array generation . Proc. SPIE 1913, 1--12. Robert A. Ulichney. 1993. Void-and-cluster method for dither array generation. Proc. SPIE 1913, 1--12."},{"key":"e_1_2_2_16_1","volume-title":"Computation of Irradiance from Triangles by Adaptive Sampling. Computer Graphics Forum 2","author":"Ure\u00f1a Carlos","year":"2000","unstructured":"Carlos Ure\u00f1a . 2000. Computation of Irradiance from Triangles by Adaptive Sampling. Computer Graphics Forum 2 ( 2000 ). Carlos Ure\u00f1a. 2000. Computation of Irradiance from Triangles by Adaptive Sampling. 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