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.\" RCSid "$Id: pabopto2xyz.1,v 1.2 2021/06/21 17:19:01 greg Exp $" |
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.TH PABOPTO2XYZ 1 3/1/2021 RADIANCE |
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.SH NAME |
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pabopto2xyz - convert a collection of single-channel BSDF measurements to CIE-XYZ colorimetry |
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.SH SYNOPSIS |
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.B pabopto2xyz |
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[ |
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.B "\-m X1 X2 X3 Y1 Y2 Y3 Z1 Z2 Z3" |
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][ |
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.B "\-o basename" |
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][ |
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.B "\-n nprocs" |
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] |
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.B "s1files.txt s2files.txt s3files.txt" |
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.SH DESCRIPTION |
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.I Pabopto2xyz |
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takes three sets of standard single-channel BSDF files, each |
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measured with a different light source and/or sensor filter to select |
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different wavelengths, combining them into an equivalent set of 3-channel BSDF data |
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files with CIE-XYZ colorimetry. |
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The 3x3 transform from the input file measurements to CIE XYZ color space is |
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set by the |
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.I \-m |
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option. |
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The default coefficients correspond to a specific set of filters in use at LBNL, |
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and are probably not applicable to any other instrument. |
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.PP |
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The |
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.I \-o |
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option is used to set the base output file name, which defaults to "pabopto_xyz". |
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To this base name, the theta and phi angles are added, along with a ".txt" suffix. |
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.PP |
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The |
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.I \-n |
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option may be supplied on Unix systems for multiple processes to speed up |
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the conversion. |
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.PP |
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The BSDF measurement file names must be listed in |
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the three required input files, |
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dileneated in each by white space. |
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File names or paths therein may not contain white space, and quoting/escaping |
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is not supported. |
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The same incident directions must be provided in all three measurement sets, |
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but may be broken into different files. |
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(I.e., two or more BSDF files may correspond to the same incident direction.)\0 |
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Only one file will be produced for each incident direction in the output. |
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.PP |
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.I Pabopto2xyz |
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works by resampling the second and third input channels to correspond to the |
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exiting directions measured in the first channel. |
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A 2-D interpolant is applied at each incident direction for channels 2 and 3, |
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the given 3x3 matrix is applied, |
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and a combined virtual measurement is produced in output files beginning with |
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the given base name. |
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For this reason, it is often preferably to place the "green" or "near-Y" |
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channel first. |
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.PP |
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The combined data files produced by |
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.I pabopto2xyz |
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are subsequently passed to |
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.I pabopto2bsdf(1) |
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to produce a Scattering Interpolant Representation (SIR) file for further |
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processing. |
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.SH EXAMPLE |
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To combine three sets of measurements in a REC709 color space and produce |
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a CIE-XYZ file for pabopto2bsdf, which produces a color SIR file: |
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.IP "" .2i |
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pabopto2xyz -m .358 .412 .180 .715 .213 .072 .119 .019 .951 -o blinds_xyz filesG.txt filesR.txt filesB.txt |
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.br |
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pabopto2bsdf blinds_xyz*.txt > blinds_xyz.sir |
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.SH AUTHOR |
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Greg Ward |
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.SH "SEE ALSO" |
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bsdf2klems(1), bsdf2rad(1), bsdf2ttree(1), bsdfview(1), genBSDF(1), |
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pabopto2bsdf(1) |
