[ViewVC] Diff of: Development/ray/doc/ray.html

Comparing ray/doc/ray.html (file contents):
Revision 1.32 by greg, Fri Nov 3 17:41:27 2023 UTC vs.
Revision 1.39 by greg, Mon Dec 9 19:21:38 2024 UTC

+<!-- RCSid $Id$ -->
+<head>
+<title>
-<
+The RADIANCE 5.4 Synthetic Imaging System
->
+The RADIANCE 6.0 Synthetic Imaging System
+</title>
+</head>
+<body>
+<p>
+<h1>
-<
+The RADIANCE 5.4 Synthetic Imaging System
->
+The RADIANCE 6.0 Synthetic Imaging System
+</h1>
+<p>
+<p>
+<dt>
-+
+        <a NAME="WGMDfunc">
-+
+        <b>WGMDfunc</b>
-+
+        </a>
-+
-+
+<dd>
-+
+        WGMDfunc is a more programmable version of <a HREF="#Trans2">trans2</a>,
-+
+        with separate modifier paths and variables to control each component.
-+
+        (WGMD stands for Ward-Geisler-Moroder-Duer, which is the basis for
-+
+        this empirical model, similar to previous ones beside Ashik2.)
-+
+        The specification of this material is given below.
-+
+<pre>
-+
+        mod WGMDfunc id
-+
++ rs_mod  rs  rs_urough rs_vrough
-+
+            ts_mod  ts  ts_urough ts_vrough
-+
+            td_mod
-+
+            ux uy uz  funcfile  transform
-+
-+
++  rfdif gfdif bfdif
-+
+            rbdif gbdif bbdif
-+
+            rtdif gtdif btdif
-+
+            A10 ..
-+
+</pre>
-+
-+
+The sum of specular reflectance (<I>rs</I>), specular transmittance (<I>ts</I>),
-+
+diffuse reflectance (<I>rfdif gfdif bfdif</I> for front and <I>rbdif gbdif bbdif</I> for back)
-+
+and diffuse transmittance (<I>rtdif gtdif btdif</I>) should be less than 1 for each
-+
+channel.
-+
-+
+<p>
-+
-+
+Unique to this material, separate modifier channels are
-+
+provided for each component.
-+
+The main modifier is used on the diffuse reflectance, both
-+
+front and back.
-+
+The <I>rs_mod</I> modifier is used for specular reflectance.
-+
+If "void" is given for <I>rs_mod</I>,
-+
+then the specular reflection color will be white.
-+
+The special "inherit" keyword may also be given, in which case
-+
+specular reflectance will share the main modifier.
-+
+This behavior is replicated for the specular transmittance modifier
-+
+<I>ts_mod</I>, which also has its own independent roughness expressions.
-+
+Finally, the diffuse transmittance modifier is given as
-+
+<I>td_mod</I>, which may also be "void" or "inherit".
-+
+Note that any spectra or color for specular components must be
-+
+carried by the named modifier(s).
-+
-+
+<p>
-+
-+
+The main advantage to this material over
-+
+<a HREF="#BRTDfunc">BRTDfunc</a> and
-+
+other programmable types described below is that the specular sampling is
-+
+well-defined, so that all components are fully computed.
-+
-+
+<p>
-+
-+
+<dt>
+        <a NAME="Dielectric">
+        <b>Dielectric</b>
+        </a>
+        A single line of text will often be accompanied by a negative spacing value.
+        A section of text meant to  depict  a  picture, perhaps using a special purpose font such as hexbit4x1.fnt, calls for uniform  spacing.
+        Reasonable  magnitudes  for  proportional  spacing are between 0.1 (for tightly spaced characters) and 0.3 (for wide spacing).
-+
-+
+<p>
-+
-+
+<dt>
-+
+        <a NAME="Spectrum">
-+
+        <b>Spectrum</b>
-+
+        </a>
-+
-+
+<dd>
-+
+        The spectrum primitive is the most basic type for introducing spectral
-+
+        color to a material.
-+
+        Since materials only provide RGB parameters, spectral patterns
-+
+        are the only way to superimpose wavelength-dependent behavior.
-+
-+
+<pre>
-+
+        mod spectrum id
-+
-+
-+
++ nmA nmB s1 s2 .. sN
-+
+</pre>
-+
-+
+<p>
-+
+        The first two real arguments indicate the extrema of the
-+
+        spectral range in nanometers.
-+
+        Subsequent real values correspond to multipliers at each wavelength.
-+
+        The nmA wavelength may be greater or less than nmB,
-+
+        but they may not be equal, and their ordering matches
-+
+        the order of the spectral values.
-+
+        A minimum of 3 values must be given, which would act
-+
+        more or less the same as a constant RGB multiplier.
-+
+        As with RGB values, spectral quantities normally range between 0
-+
+        and 1 at each wavelength, or average to 1.0 against a standard
-+
+        sensitivity functions such as V(lambda).
-+
+        The best results obtain when the spectral range and number
-+
+        of samples match rendering options, though resampling will handle
-+
+        any differences, zero-filling wavelenths outside the nmA to nmB
-+
+        range.
-+
+        A warning will be issued if the given wavelength range does not
-+
+        adequately cover the visible spectrum.
-+
-+
+<p>
-+
-+
+<dt>
-+
+        <a NAME="Specfile">
-+
+        <b>Specfile</b>
-+
+        </a>
-+
-+
+<dd>
-+
+        The specfile primitive is equivalent to the spectrum type, but
-+
+        the wavelength range and values are contained in a 1-dimensional
-+
+        data file.
-+
+        This may be a more convenient way to specify a spectral color,
-+
+        especially one corresponding to a standard illuminant such as D65
-+
+        or a library of measured spectra.
-+
-+
+<pre>
-+
+        mod specfile id
-+
+datafile
-+
-+
-+
+</pre>
-+
-+
+<p>
-+
+        As with the spectrum type, rendering wavelengths outside the defined
-+
+        range will be zero-filled.
-+
+        Unlike the spectrum type, the file may contain non-uniform samples.
-+
-+
+<p>
-+
-+
+<dt>
-+
+        <a NAME="Specfunc">
-+
+        <b>Specfunc</b>
-+
+        </a>
-+
-+
+<dd>
-+
+        The specfunc primitive offers dynamic control over a spectral
-+
+        pattern, similar to the colorfunc type.
-+
-+
+<pre>
-+
+        mod specfunc id
-+
++ sfunc funcfile transform
-+
-+
++ nmA nmB A3 ..
-+
+</pre>
-+
-+
+<p>
-+
+        Like the spectrum primitive, the wavelength range is specified
-+
+        in the first two real arguments, and additional real values are
-+
+        set in the evaluation context.
-+
+        This function is fed a wavelenth sample
-+
+        between nmA and nmB as its only argument,
-+
+        and it returns the corresponding spectral intensity.
-+
-+
+<dt>
-+
+       <a NAME="Specdata">
-+
+       <b>Specdata</b>
-+
+       </a>
-+
-+
+<dd>
-+
+        Specdata is like brightdata and colordata, but with more
-+
+        than 3 specular samples.
-+
-+
+<pre>
-+
+        mod specdata id
-+
++n+
-+
+                func datafile
-+
+                funcfile x1 x2 .. xn transform
-+
-+
+        m A1 A2 .. Am
-+
+</pre>
-+
-+
+<p>
-+
+        The data file must have one more dimension than the coordinate
-+
+        variable count, as this final dimension corresponds to the covered
-+
+        spectrum.
-+
+        The starting and ending wavelengths are specified in "datafile"
-+
+        as well as the number of spectral samples.
-+
+        The function "func" will be called with two parameters, the
-+
+        interpolated spectral value for the current coordinate and the
-+
+        associated wavelength.
-+
+        If the spectrum is broken into 12 components, then 12 calls
-+
+        will be made to "func" for the relevant ray evaluation.
-+
-+
+<dt>
-+
+       <a NAME="Specpict">
-+
+       <b>Specpict</b>
-+
+       </a>
-+
-+
+<dd>
-+
+        Specpict is a special case of specdata, where the pattern is
-+
+        a hyperspectral image stored in the common-exponent file format.
-+
+        The dimensions of the image data are determined by the picture
-+
+        just as with the colorpict primitive.
-+
-+
+<pre>
-+
+        mod specpict id
 +
-+
+                func specfile
-+
+                funcfile u v transform
-+
-+
+        m A1 A2 .. Am
-+
+</pre>
-+
-+
+<p>
-+
+        The function "func" is called with the interpolated pixel value
-+
+        and the wavelength sample in nanometers, the same as specdata,
-+
+        with as many calls made as there are components in "specfile".
+</dl>

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Comparing ray/doc/ray.html (file contents): Revision 1.32 by greg, Fri Nov 3 17:41:27 2023 UTC vs. Revision 1.39 by greg, Mon Dec 9 19:21:38 2024 UTC

Diff Legend

Comparing ray/doc/ray.html (file contents):
Revision 1.32 by greg, Fri Nov 3 17:41:27 2023 UTC vs.
Revision 1.39 by greg, Mon Dec 9 19:21:38 2024 UTC