ViewVC Help
View File | Revision Log | Show Annotations | Download File | Root Listing
root/Development/ray/doc/ray.html
(Generate patch)

Comparing ray/doc/ray.html (file contents):
Revision 1.9 by greg, Fri Mar 12 18:43:30 2010 UTC vs.
Revision 1.11 by greg, Wed Apr 6 22:03:04 2011 UTC

# Line 1 | Line 1
1   <html>
2   <head>
3   <title>
4 < The RADIANCE 4.0 Synthetic Imaging System
4 > The RADIANCE 4.1 Synthetic Imaging System
5   </title>
6   </head>
7   <body>
# Line 9 | Line 9 | The RADIANCE 4.0 Synthetic Imaging System
9   <p>
10  
11   <h1>
12 < The RADIANCE 4.0 Synthetic Imaging System
12 > The RADIANCE 4.1 Synthetic Imaging System
13   </h1>
14  
15   <p>
# 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 + <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 &quot;up&quot; 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.)
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 1921 | 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>

Diff Legend

– Removed lines
+ Added lines
< Changed lines (old)
> Changed lines (new)