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<!-- RCSid $Id$ --> |
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<head> |
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<title> |
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The RADIANCE 5.4 Synthetic Imaging System |
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The RADIANCE 6.0 Synthetic Imaging System |
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</title> |
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</head> |
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<body> |
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<p> |
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<h1> |
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The RADIANCE 5.4 Synthetic Imaging System |
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The RADIANCE 6.0 Synthetic Imaging System |
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</h1> |
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<p> |
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A section of text meant to depict a picture, perhaps using a special purpose font such as hexbit4x1.fnt, calls for uniform spacing. |
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Reasonable magnitudes for proportional spacing are between 0.1 (for tightly spaced characters) and 0.3 (for wide spacing). |
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<p> |
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<dt> |
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<a NAME="Spectrum"> |
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<b>Spectrum</b> |
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</a> |
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|
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<dd> |
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The spectrum primitive is the most basic type for introducing spectral |
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color to a material. |
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Since materials only provide RGB parameters, spectral patterns |
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are the only way to superimpose wavelength-dependent behavior. |
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|
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<pre> |
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mod spectrum id |
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0 |
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0 |
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5+ nmA nmB s1 s2 .. sN |
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</pre> |
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|
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<p> |
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The first two real arguments indicate the extrema of the |
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spectral range in nanometers. |
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Subsequent real values correspond to multipliers at each wavelength. |
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The nmA wavelength may be greater or less than nmB, |
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but they may not be equal, and their ordering matches |
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the order of the spectral values. |
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A minimum of 3 values must be given, which would act |
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more or less the same as a constant RGB multiplier. |
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As with RGB values, spectral quantities normally range between 0 |
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and 1 at each wavelength, or average to 1.0 against a standard |
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sensitivity functions such as V(lambda). |
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The best results obtain when the spectral range and number |
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of samples match rendering options, though resampling will handle |
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any differences, zero-filling wavelenths outside the nmA to nmB |
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range. |
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A warning will be issued if the given wavelength range does not |
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adequately cover the visible spectrum. |
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|
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<p> |
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|
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<dt> |
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<a NAME="Specfile"> |
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<b>Specfile</b> |
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</a> |
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|
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<dd> |
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The specfile primitive is equivalent to the spectrum type, but |
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the wavelength range and values are contained in a 1-dimensional |
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data file. |
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This may be a more convenient way to specify a spectral color, |
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especially one corresponding to a standard illuminant such as D65 |
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or a library of measured spectra. |
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|
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<pre> |
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mod specfile id |
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1 datafile |
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0 |
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0 |
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</pre> |
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|
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<p> |
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As with the spectrum type, rendering wavelengths outside the defined |
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range will be zero-filled. |
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Unlike the spectrum type, the file may contain non-uniform samples. |
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|
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<p> |
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|
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<dt> |
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<a NAME="Specfunc"> |
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<b>Specfunc</b> |
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</a> |
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|
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<dd> |
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The specfunc primitive offers dynamic control over a spectral |
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pattern, similar to the colorfunc type. |
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|
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<pre> |
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mod specfunc id |
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2+ sfunc funcfile transform |
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0 |
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2+ nmA nmB A3 .. |
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</pre> |
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|
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<p> |
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Like the spectrum primitive, the wavelength range is specified |
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in the first two real arguments, and additional real values are |
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set in the evaluation context. |
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This function is fed a wavelenth sample |
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between nmA and nmB as its only argument, |
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and it returns the corresponding spectral intensity. |
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|
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<dt> |
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<a NAME="Specdata"> |
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<b>Specdata</b> |
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</a> |
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|
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<dd> |
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Specdata is like brightdata and colordata, but with more |
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than 3 specular samples. |
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|
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<pre> |
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mod specdata id |
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3+n+ |
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func datafile |
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funcfile x1 x2 .. xn transform |
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0 |
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m A1 A2 .. Am |
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</pre> |
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|
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<p> |
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The data file must have one more dimension than the coordinate |
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variable count, as this final dimension corresponds to the covered |
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spectrum. |
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The starting and ending wavelengths are specified in "datafile" |
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as well as the number of spectral samples. |
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The function "func" will be called with two parameters, the |
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interpolated spectral value for the current coordinate and the |
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associated wavelength. |
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If the spectrum is broken into 12 components, then 12 calls |
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will be made to "func" for the relevant ray evaluation. |
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|
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<dt> |
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<a NAME="Specpict"> |
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<b>Specpict</b> |
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</a> |
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|
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<dd> |
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Specpict is a special case of specdata, where the pattern is |
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a hyperspectral image stored in the common-exponent file format. |
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The dimensions of the image data are determined by the picture |
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just as with the colorpict primitive. |
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|
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<pre> |
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mod specpict id |
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5+ |
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func specfile |
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funcfile u v transform |
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0 |
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m A1 A2 .. Am |
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</pre> |
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|
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<p> |
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The function "func" is called with the interpolated pixel value |
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and the wavelength sample in nanometers, the same as specdata, |
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with as many calls made as there are components in "specfile". |
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|
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</dl> |
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<p> |
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</h2> |
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<p> |
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<ul> |
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<li>Ward, Gregory J., Bruno Bueno, David Geisler-Moroder, |
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Lars O. Grobe, Jacob C. Jonsson, Eleanor |
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S. Lee, Taoning Wang, Helen Rose Wilson, |
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"<a href="https://doi.org/10.1016/j.enbuild.2022.111890">Daylight |
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Simulation Workflows Incorporating Measured Bidirectional |
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Scattering Distribution Functions</a>" |
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<em>Energy & Buildings</em>, Vol. 259, No. 11890, 2022. |
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<li>Wang, Taoning, Gregory Ward, Eleanor Lee, |
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"<a href="https://authors.elsevier.com/a/1XQ0a1M7zGwT7v">Efficient |
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modeling of optically-complex, non-coplanar exterior shading: |
