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# Line 1 | Line 1
1   <html>
2   <head>
3   <title>
4 < The RADIANCE 3.8 Synthetic Imaging System
4 > The RADIANCE 4.1 Synthetic Imaging System
5   </title>
6   </head>
7   <body>
# Line 9 | Line 9 | The RADIANCE 3.8 Synthetic Imaging System
9   <p>
10  
11   <h1>
12 < The RADIANCE 3.8 Synthetic Imaging System
12 > The RADIANCE 4.1 Synthetic Imaging System
13   </h1>
14  
15   <p>
# Line 659 | Line 659 | a perfectly scattering medium (no absorption).
659   The scattering eccentricity parameter will likewise override the global
660   setting if it is present.
661   Scattering eccentricity indicates how much scattered light favors the
662 < forward direction, as fit by the Heyney-Greenstein function:
662 > forward direction, as fit by the Henyey-Greenstein function:
663  
664   <pre>
665          P(theta) = (1 - g*g) / (1 + g*g - 2*g*cos(theta))^1.5
# Line 1053 | Line 1053 | unless the line integrals consider enclosed geometry.
1053   <p>
1054  
1055   <dt>
1056 +        <a NAME="BSDF">
1057 +        <b>BSDF</b>
1058 +        </a>
1059 +
1060 + <dd>
1061 +        The BSDF material type loads an XML (eXtensible Markup Language)
1062 +        file describing a bidirectional scattering distribution function.
1063 +        Real arguments to this material may define additional
1064 +        diffuse components that augment the BSDF data.
1065 +        String arguments are used to define thickness for proxied
1066 +        surfaces and the "up" orientation for the material.
1067 +
1068 + <pre>
1069 +        mod BSDF id
1070 +        6+ thick BSDFfile ux uy uz funcfile transform
1071 +        0
1072 +        0|3|6|9
1073 +                rfdif gfdif bfdif
1074 +                rbdif gbdif bbdif
1075 +                rtdif gtdif btdif
1076 + </pre>
1077 +
1078 + <p>
1079 +        The first string argument is a "thickness" parameter that may be used
1080 +        to hide detail geometry being proxied by an aggregate BSDF material.
1081 +        If a view or shadow ray hits a BSDF proxy with non-zero thickness,
1082 +        it will pass directly through as if the surface were not there.
1083 +        Similar to the illum type, this permits direct viewing and
1084 +        shadow testing of complex geometry.
1085 +        The BSDF is used when a scattered (indirect) ray hits the surface,
1086 +        and any transmitted sample rays will be offset by the thickness amount
1087 +        to avoid the hidden geometry and gather samples from the other side.
1088 +        In this manner, BSDF surfaces can improve the results for indirect
1089 +        scattering from complex systems without sacrificing appearance or
1090 +        shadow accuracy.
1091 +        If the BSDF has transmission and back-side reflection data,
1092 +        a parallel BSDF surface may be
1093 +        placed slightly less than the given thickness away from the front surface
1094 +        to enclose the complex geometry on both sides.
1095 + <p>
1096 +        The second string argument is the name of the BSDF file, which is
1097 +        found in the usual auxiliary locations.
1098 +        The following three string parameters name variables for an "up" vector,
1099 +        which together with the surface normal, define the
1100 +        local coordinate system that orients the BSDF.
1101 +        These variables, along with the thickness, are defined in a function
1102 +        file given as the next string argument.
1103 +        An optional transform is used to scale the thickness and reorient the up vector.
1104 + <p>
1105 +        If no real arguments are given, the BSDF is used by itself to determine
1106 +        reflection and transmission.
1107 +        If there are at least 3 real arguments, the first triplet is an
1108 +        additional diffuse reflectance for the front side.
1109 +        At least 6 real arguments adds diffuse reflectance to the rear side of the surface.
1110 +        If there are 9 real arguments, the final triplet will be taken as an additional
1111 +        diffuse transmittance.
1112 +        All diffuse components as well as the non-diffuse transmission are
1113 +        modified by patterns applied to this material.
1114 +        The non-diffuse reflection from either side are unaffected.
1115 +        Textures perturb the effective surface normal in the usual way.
1116 + <p>
1117 +        The surface normal of this type is not altered to face the incoming ray,
1118 +        so the front and back BSDF reflections may differ.
1119 +        (Transmission is identical front-to-back by physical law.)\0
1120 +        If back visibility is turned off during rendering and there is no
1121 +        transmission or back-side reflection, only then the surface will be
1122 +        invisible from behind.
1123 +        Unlike other data-driven material types, the BSDF type is fully
1124 +        supported and all parts of the distribution are properly sampled.
1125 + <p>
1126 +
1127 + <dt>
1128          <a NAME="Antimatter">
1129          <b>Antimatter</b>
1130          </a>
# Line 1365 | Line 1437 | A mixfunc mixes  two  modifiers  procedurally.   It  i
1437          which serves as a form of opacity control when used with a material.)
1438          Vname is the coefficient defined in funcfile that determines  the  influence  of  foreground.  
1439          The background coefficient is always (1-vname).  
1368 –        Since the references are not resolved until run-time,  the  last  definitions  of  the modifier id's will be used.  
1369 –        This can result in modifier loops, which are detected by the renderer.
1440  
1441   <p>
1442  
# Line 1528 | Line 1598 | If no file is needed by a given primitive because all
1598   the  required  variables  are global,  
1599   a  period  (`.')  can be given in place of the file name.  
1600   It is also possible to give an expression instead
1601 < of a  straight  variable  name  in  a scene file,
1602 < although such expressions should be kept
1533 < simple if possible.
1534 < Also, functions (requiring parameters) must be given
1601 > of a  straight  variable  name  in  a scene file.
1602 > Functions (requiring parameters) must be given
1603   as names and not as expressions.
1604  
1605   <p>
# Line 1749 | Line 1817 | or converted a standard image format using one of the
1817   <pre>
1818   The Radiance Software License, Version 1.0
1819  
1820 < Copyright (c) 1990 - 2006 The Regents of the University of California,
1820 > Copyright (c) 1990 - 2010 The Regents of the University of California,
1821   through Lawrence Berkeley National Laboratory.   All rights reserved.
1822  
1823   Redistribution and use in source and binary forms, with or without
# Line 1823 | Line 1891 | Ecole  Polytechnique  Federale de Lausanne (EPFL Unive
1891   <p>
1892   <ul>
1893      <li>Cater, Kirsten, Alan Chalmers, Greg Ward,
1894 <        &quot;<a href="papers/egsr2003.pdf">Detail to Attention:
1894 >        &quot;<a href="http://www.anyhere.com/gward/papers/egsr2003.pdf">Detail to Attention:
1895          Exploiting Visual Tasks for Selective Rendering</a>,&quot;
1896          <em>Eurographics Symposium
1897          on Rendering 2003</em>, June 2003.
1898      <li>Ward, Greg, Elena Eydelberg-Vileshin,
1899 <        ``<a HREF="http://viz.cs.berkeley.edu/~gwlarson/papers/egwr02/index.html">Picture Perfect RGB
1899 >        ``<a HREF="http://www.anyhere.com/gward/papers/egwr02/index.html">Picture Perfect RGB
1900          Rendering Using Spectral Prefiltering and Sharp Color Primaries</a>,''
1901          Thirteenth Eurographics Workshop on Rendering (2002),
1902          P. Debevec and S. Gibson (Editors), June 2002.
1903      <li>Ward, Gregory,
1904 <        ``<a HREF="http://viz.cs.berkeley.edu/~gwlarson/papers/cic01.pdf">High Dynamic Range Imaging</a>,''
1904 >        ``<a HREF="http://www.anyhere.com/gward/papers/cic01.pdf">High Dynamic Range Imaging</a>,''
1905          Proceedings of the Ninth Color Imaging Conference, November 2001.
1906      <li>Ward, Gregory and Maryann Simmons,
1907 <        ``<a HREF="http://viz.cs.berkeley.edu/~gwlarson/papers/tog99.pdf">
1907 >        ``<a HREF="http://www.anyhere.com/gward/papers/tog99.pdf">
1908          The Holodeck Ray Cache: An Interactive Rendering System for Global Illumination in Nondiffuse
1909          Environments</a>,'' ACM Transactions on Graphics, 18(4):361-98, October 1999.
1910 <    <li>Larson, G.W., ``<a HREF="http://viz.cs.berkeley.edu/~gwlarson/papers/ewp98.pdf">The Holodeck: A Parallel
1910 >    <li>Larson, G.W., ``<a HREF="http://www.anyhere.com/gward/papers/ewp98.pdf">The Holodeck: A Parallel
1911          Ray-caching Rendering System</a>,'' Proceedings of the Second
1912          Eurographics Workshop on Parallel Graphics and Visualisation,
1913          September 1998.
# Line 1925 | Line 1993 | SURFACES       MATERIALS       TEXTURES        PATTERNS        MIXTURES</h4>
1993                  <a HREF="#Plasdata">Plasdata</a>
1994                  <a HREF="#Metdata">Metdata</a>
1995                  <a HREF="#Transdata">Transdata</a>
1996 +                <a HREF="#BSDF">BSDF</a>
1997                  <a HREF="#Antimatter">Antimatter</a>
1998                                  
1999   </pre>

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