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Rendering with these materials can be costly, since we must simulate these transport effects at every evaluation of the underlying reflectance model. Rendering an image requires thousands of such evaluations, per pixel. Recent work treats this complexity by introducing significant approximations, requiring large precomputed datasetsper material, or simplifying the light transport simulations within the materials. Even the most effective of these methods struggle with the complexity induced by high\u2010frequency variation in reflectance parameters and micro\u2010surface normal variation, as well as anisotropic volumetric scattering between the layer interfaces. We present a more efficient, unbiased estimator for light transport in such general, complex layered appearance models. By conducting an analysis of the types of transport paths that contribute most to the aggregate reflectance dynamics, we propose an effective and unbiased path sampling method that reduces variance in the reflectance evaluations. Our method additionally supports reflectance importance sampling, does not rely on any precomputation, and so integrates readily into existing renderers. We consistently outperform the state\u2010of\u2010the\u2010art by~2 \u2013 6<\/jats:bold>\u00d7 in equal\u2010quality (i.e., equal error) comparisons.<\/jats:p>","DOI":"10.1111\/cgf.13936","type":"journal-article","created":{"date-parts":[[2020,7,13]],"date-time":"2020-07-13T11:37:33Z","timestamp":1594640253000},"page":"363-371","update-policy":"http:\/\/dx.doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":12,"title":["An Efficient Transport Estimator for Complex Layered Materials"],"prefix":"10.1111","volume":"39","author":[{"ORCID":"http:\/\/orcid.org\/0000-0002-6439-1974","authenticated-orcid":false,"given":"Luis E.","family":"Gamboa","sequence":"first","affiliation":[{"name":"Universit\u00e9 de Montr\u00e9al Canada"}]},{"ORCID":"http:\/\/orcid.org\/0000-0003-0773-2725","authenticated-orcid":false,"given":"Adrien","family":"Gruson","sequence":"additional","affiliation":[{"name":"McGill University Canada"}]},{"ORCID":"http:\/\/orcid.org\/0000-0002-4279-1774","authenticated-orcid":false,"given":"Derek","family":"Nowrouzezahrai","sequence":"additional","affiliation":[{"name":"McGill University Canada"}]}],"member":"311","published-online":{"date-parts":[[2020,7,13]]},"reference":[{"key":"e_1_2_8_2_2","doi-asserted-by":"publisher","DOI":"10.1145\/3197517.3201289"},{"key":"e_1_2_8_3_2","unstructured":"BitterliB.:Rendering resources 2016. 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