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# Line 1 | Line 1
1   <html>
2   <head>
3   <title>
4 < The RADIANCE 3.7 Synthetic Imaging System
4 > The RADIANCE 4.1 Synthetic Imaging System
5   </title>
6   </head>
7   <body>
# Line 9 | Line 9 | The RADIANCE 3.7 Synthetic Imaging System
9   <p>
10  
11   <h1>
12 < The RADIANCE 3.7 Synthetic Imaging System
12 > The RADIANCE 4.1 Synthetic Imaging System
13   </h1>
14  
15   <p>
# Line 564 | Line 564 | A material defines the way light interacts with a  sur
564          </a>
565  
566   <dd>
567 <        Mirror is used for planar surfaces that produce  secondary source reflections.  
567 >        Mirror is used for planar surfaces that produce  virtual source reflections.  
568          This material should be used sparingly, as it may cause the light source calculation to  blow up  if  it is applied to many small surfaces.  
569          This material is only supported for flat surfaces  such  as  <a HREF="#Polygon">polygons</a>  and <a HREF="#Ring">rings</a>.  
570          The arguments are simply the RGB reflectance values, which should be between 0 and 1.  
# Line 587 | Line 587 | This is only appropriate if the surface hides other (m
587          </a>
588  
589   <dd>
590 <        The prism1 material is for  general  light  redirection from prismatic glazings, generating secondary light sources.
590 >        The prism1 material is for  general  light  redirection from prismatic glazings, generating virtual light sources.
591          It can only be used  to  modify  a  planar  surface  
592          (i.e.,  a <a HREF="#Polygon">polygon</a>  or <a HREF="#Ring">disk</a>)
593          and should not result in either light concentration or scattering.  
594          The new direction of the ray  can be  on either side of the material,
595 <        and the definitions must have the correct bidirectional properties to  work  properly with  secondary light sources.  
595 >        and the definitions must have the correct bidirectional properties to  work  properly with virtual light sources.  
596          The arguments give the coefficient for the redirected light and its direction.
597  
598   <pre>
# 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 &quot;up&quot; 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 &quot;thickness&quot; 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 +        The sign of the thickness is important, as it indicates
1096 +        whether the proxied geometry is behind the <em>BSDF</em>
1097 +        surface (when thickness is positive) or in front (when
1098 +        thickness is negative).
1099 + <p>
1100 +        The second string argument is the name of the BSDF file,
1101 +        which is found in the usual auxiliary locations.  The
1102 +        following three string parameters name variables for an
1103 +        &quot;up&quot; vector, which together with the surface
1104 +        normal, define the local coordinate system that orients the
1105 +        BSDF.  These variables, along with the thickness, are defined
1106 +        in a function file given as the next string argument.  An
1107 +        optional transform is used to scale the thickness and
1108 +        reorient the up vector.
1109 + <p>
1110 +        If no real arguments are given, the BSDF is used by itself
1111 +        to determine reflection and transmission.  If there are at
1112 +        least 3 real arguments, the first triplet is an additional
1113 +        diffuse reflectance for the front side.  At least 6 real
1114 +        arguments adds diffuse reflectance to the rear side of the
1115 +        surface.  If there are 9 real arguments, the final triplet
1116 +        will be taken as an additional diffuse transmittance.  All
1117 +        diffuse components as well as the non-diffuse transmission
1118 +        are modified by patterns applied to this material.  The
1119 +        non-diffuse reflection from either side are unaffected.
1120 +        Textures perturb the effective surface normal in the usual
1121 +        way.
1122 + <p>
1123 +        The surface normal of this type is not altered to face the
1124 +        incoming ray, so the front and back BSDF reflections may
1125 +        differ.  (Transmission is identical front-to-back by physical
1126 +        law.) If back visibility is turned off during rendering and
1127 +        there is no transmission or back-side reflection, only then
1128 +        the surface will be invisible from behind.  Unlike other
1129 +        data-driven material types, the BSDF type is fully supported
1130 +        and all parts of the distribution are properly sampled.
1131 + <p>
1132 +
1133 + <dt>
1134          <a NAME="Antimatter">
1135          <b>Antimatter</b>
1136          </a>
# Line 1365 | Line 1443 | A mixfunc mixes  two  modifiers  procedurally.   It  i
1443          which serves as a form of opacity control when used with a material.)
1444          Vname is the coefficient defined in funcfile that determines  the  influence  of  foreground.  
1445          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.
1446  
1447   <p>
1448  
# Line 1528 | Line 1604 | If no file is needed by a given primitive because all
1604   the  required  variables  are global,  
1605   a  period  (`.')  can be given in place of the file name.  
1606   It is also possible to give an expression instead
1607 < of a  straight  variable  name  in  a scene file,
1608 < although such expressions should be kept
1533 < simple if possible.
1534 < Also, functions (requiring parameters) must be given
1607 > of a  straight  variable  name  in  a scene file.
1608 > Functions (requiring parameters) must be given
1609   as names and not as expressions.
1610  
1611   <p>
# Line 1749 | Line 1823 | or converted a standard image format using one of the
1823   <pre>
1824   The Radiance Software License, Version 1.0
1825  
1826 < Copyright (c) 1990 - 2002 The Regents of the University of California,
1826 > Copyright (c) 1990 - 2010 The Regents of the University of California,
1827   through Lawrence Berkeley National Laboratory.   All rights reserved.
1828  
1829   Redistribution and use in source and binary forms, with or without
# Line 1822 | Line 1896 | Ecole  Polytechnique  Federale de Lausanne (EPFL Unive
1896   </h2>
1897   <p>
1898   <ul>
1899 +    <li>Cater, Kirsten, Alan Chalmers, Greg Ward,
1900 +        &quot;<a href="http://www.anyhere.com/gward/papers/egsr2003.pdf">Detail to Attention:
1901 +        Exploiting Visual Tasks for Selective Rendering</a>,&quot;
1902 +        <em>Eurographics Symposium
1903 +        on Rendering 2003</em>, June 2003.
1904      <li>Ward, Greg, Elena Eydelberg-Vileshin,
1905 <        ``<a HREF="http://viz.cs.berkeley.edu/~gwlarson/papers/egwr02/index.html">Picture Perfect RGB
1905 >        ``<a HREF="http://www.anyhere.com/gward/papers/egwr02/index.html">Picture Perfect RGB
1906          Rendering Using Spectral Prefiltering and Sharp Color Primaries</a>,''
1907          Thirteenth Eurographics Workshop on Rendering (2002),
1908          P. Debevec and S. Gibson (Editors), June 2002.
1909      <li>Ward, Gregory,
1910 <        ``<a HREF="http://viz.cs.berkeley.edu/~gwlarson/papers/cic01.pdf">High Dynamic Range Imaging</a>,''
1910 >        ``<a HREF="http://www.anyhere.com/gward/papers/cic01.pdf">High Dynamic Range Imaging</a>,''
1911          Proceedings of the Ninth Color Imaging Conference, November 2001.
1912      <li>Ward, Gregory and Maryann Simmons,
1913 <        ``<a HREF="http://viz.cs.berkeley.edu/~gwlarson/papers/tog99.pdf">
1913 >        ``<a HREF="http://www.anyhere.com/gward/papers/tog99.pdf">
1914          The Holodeck Ray Cache: An Interactive Rendering System for Global Illumination in Nondiffuse
1915          Environments</a>,'' ACM Transactions on Graphics, 18(4):361-98, October 1999.
1916 <    <li>Larson, G.W., ``<a HREF="http://viz.cs.berkeley.edu/~gwlarson/papers/ewp98.pdf">The Holodeck: A Parallel
1916 >    <li>Larson, G.W., ``<a HREF="http://www.anyhere.com/gward/papers/ewp98.pdf">The Holodeck: A Parallel
1917          Ray-caching Rendering System</a>,'' Proceedings of the Second
1918          Eurographics Workshop on Parallel Graphics and Visualisation,
1919          September 1998.
# Line 1920 | Line 1999 | SURFACES       MATERIALS       TEXTURES        PATTERNS        MIXTURES</h4>
1999                  <a HREF="#Plasdata">Plasdata</a>
2000                  <a HREF="#Metdata">Metdata</a>
2001                  <a HREF="#Transdata">Transdata</a>
2002 +                <a HREF="#BSDF">BSDF</a>
2003                  <a HREF="#Antimatter">Antimatter</a>
2004                                  
2005   </pre>

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