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.\" RCSid "$Id$" |
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.\" Print using the -ms macro package |
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< |
.DA 09/18/2015 |
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.DA 07/10/2016 |
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.LP |
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< |
.tl """Copyright \(co 2015 Regents, University of California |
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.tl """Copyright \(co 2017 Regents, University of California |
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.sp 2 |
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.TL |
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The |
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8 red green blue spec urough vrough trans tspec |
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.DE |
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.LP |
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.UL Ashik2 |
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.PP |
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Ashik2 is the anisotropic reflectance model by Ashikhmin & Shirley. |
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The string arguments are the same as for plastic2, but the real |
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arguments have additional flexibility to specify the specular color. |
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Also, rather than roughness, specular power is used, which has no |
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physical meaning other than larger numbers are equivalent to a smoother |
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surface. |
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.DS |
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mod ashik2 id |
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4+ ux uy uz funcfile transform |
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0 |
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8 dred dgrn dblu sred sgrn sblu u-power v-power |
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.DE |
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.LP |
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.UL Dielectric |
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.PP |
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A dielectric material is transparent, and it refracts light |
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Unlike other data-driven material types, the BSDF type is fully |
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supported and all parts of the distribution are properly sampled. |
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.LP |
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.UL sBSDF |
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.PP |
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The sBSDF material is identical to the BSDF type with two important |
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differences. |
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First, proxy geometry is not supported, so there is no thickness parameter. |
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Second, an sBSDF is assumed to have some specular through component, which |
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is treated specially during the direct calculation and when viewing the |
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material. |
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Based on the BSDF data, the coefficient of specular transmission is |
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determined and used for modifying unscattered shadow and view rays. |
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.DS |
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mod sBSDF id |
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5+ BSDFfile ux uy uz funcfile transform |
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0 |
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0|3|6|9 |
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rfdif gfdif bfdif |
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rbdif gbdif bbdif |
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rtdif gtdif btdif |
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.DE |
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.LP |
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If a material has no specular transmitted component, it is much better |
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to use the BSDF type with a zero thickness than to use sBSDF. |
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.LP |
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.UL Antimatter |
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.PP |
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Antimatter is a material that can "subtract" volumes from other volumes. |
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The first modifier will also be used to shade the area leaving the |
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antimatter volume and entering the regular volume. |
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If mod1 is void, the antimatter volume is completely invisible. |
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Antimatter does not work properly with the material type "trans", |
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and multiple antimatter surfaces should be disjoint. |
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If shading is desired at antimatter surfaces, it is important |
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that the related volumes are closed with outward-facing normals. |
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Antimatter surfaces should not intersect with other antimatter boundaries, |
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and it is unwise to use the same modifier in nested antimatter volumes. |
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The viewpoint must be outside all volumes concerned for a correct |
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rendering. |
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.NH 3 |
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in Lausanne, Switzerland. |
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.NH 1 |
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References |
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.LP |
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Lee, Eleanor S., David Geisler-Moroder, Gregory Ward, |
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``Modeling the direct sun component in buildings using matrix |
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algebraic approaches: Methods and validation,'' |
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.I Solar Energy, |
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vol. 160, 15 January 2018, pp 380-395. |
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.LP |
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Ward, G., M. Kurt & N. Bonneel, |
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``Reducing Anisotropic BSDF Measurement to Common Practice,'' |
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.I Workshop on Material Appearance Modeling, |
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2014. |
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.LP |
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McNeil, A., C.J. Jonsson, D. Appelfeld, G. Ward, E.S. Lee, |
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``A validation of a ray-tracing tool used to generate |
