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.SH SYNOPSIS |
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.B bsdf2ttree |
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[ |
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.B "\-pC" |
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][ |
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.B "{+|-}a" |
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][ |
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.B "\-g Nlog2" |
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][ |
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< |
.B "\-t pctcull |
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< |
] |
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< |
[ |
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.B "\-t pctcull" |
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> |
][ |
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> |
.B "\-n nss" |
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> |
][ |
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.B "\-s thresh" |
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][ |
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.B "\-l maxlobes" |
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> |
][ |
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.B "bsdf.sir .." |
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] |
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.br |
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.B bsdf2ttree |
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.B "\-t{3|4}" |
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[ |
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.B "\-pC" |
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][ |
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.B "{+|-}a" |
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+ |
][ |
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.B "\-g Nlog2" |
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][ |
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< |
.B "\-t pctcull |
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> |
.B "\-t pctcull" |
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][ |
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+ |
.B "\-n nss" |
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][ |
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.B "\-s thresh" |
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][ |
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.B "{+|-}forward" |
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][ |
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.B "{+|-}backward" |
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][ |
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< |
.B "\-e expr |
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> |
.B "\-e expr" |
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][ |
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< |
.B "\-f file |
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> |
.B "\-f file" |
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] |
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.B bsdf_func |
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.SH DESCRIPTION |
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A complete XML description is written to the standard output, |
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which is normally redirected to a file. |
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.PP |
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The |
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.I \-p |
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option by itself turns off the progress bar, whose length may be set |
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by an immediately following integer argument. |
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(The default progress bar length is 79 characters.)\0 |
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.PP |
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The |
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.I \+a |
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option turns on reciprocity averaging for isotropic scattering or anisotropic reflection. |
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Normally off (-a), this enforces each tensor-tree hemisphere to follow symmetry |
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implied by Helmholtz reciprocity, and is designed to reduce noise in measured data. |
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However, for some data, reciprocity averaging can make the output worse. |
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.PP |
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The maximum resolution of the tensor tree may be controlled by the |
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.I \-g |
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option, which defaults to a value of 6. |
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Setting this parameter to -1 turns culling off entirely, which may be |
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useful for comparisons. |
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.PP |
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The |
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.I \-n |
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option controls the number of super-samples to send in patches whose |
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difference to its neighbors exceeds some threshold. |
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The default number of super-samples is 256. |
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The difference threshold for super-sampling is controlled by the |
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.I \-s |
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option, and defaults to 0.35. |
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.PP |
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The first invocation form takes a intermediate scattering representation |
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as produced by |
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.I pabopto2bsdf(1) |
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the four components, and if the first component |
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is isotropic, all components must be isotropic. |
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A similar rule holds for anisotropic inputs. |
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The |
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.I \-l |
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option may be used to specify the maximum number of lobes in any |
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interpolated radial basis function. |
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The default value is 15000, which generally keeps the interpolation tractable. |
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Setting the value to 0 turns off this limit. |
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Parameter options may be altered between input files, in case a different |
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resolution or culling percentage is indicated for transmission versus |
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reflection for example. |
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.PP |
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In the second invocation form, |
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.I bsdf2ttree |
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options, and should obey both Helmholtz reciprocity and |
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integrate to less than 1 over each projected incident hemisphere |
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for energy conservation. |
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The variable and function definitions in each |
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.I \-f source |
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file are read and compiled from the RADIANCE library where it is found. |
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If the |
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.I \-t3 |
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option is specified, the defined function is assumed to be isotropic. |
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is recommended when rays will be impinging from either side. |
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.SH EXAMPLE |
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To take two components of an intermediate BSDF representation and create |
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< |
a high-resolution tensor tree with 85% culling: |
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> |
a high-resolution tensor tree with 85% culling on transmission and 95% |
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> |
culling on reflection: |
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.IP "" .2i |
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< |
bsdf2ttree -g 7 -t 85 transmitted.sir reflected.sir > combined.xml |
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> |
bsdf2ttree -g 7 -t 85 transmitted.sir -t 95 reflected.sir > combined.xml |
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.PP |
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To create a low-res BSDF corresponding to a one-sided, |
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isotropic Phong distribution: |
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.IP "" .2i |
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bsdf2ttree -g 5 -t3 -e 'phong(ix,iy,iz,ox,oy,oz) = if(iz, .1+((iz+oz)/sqrt((ix+ox)^2+(iy+oy)^2+(iz+oz)^2))^50, 0)' phong > phong.xml |
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.SH ENVIRONMENT |
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RAYPATH the directories to check for auxiliary files. |
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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), icalc(1), genBSDF(1), pkgBSDF(1) |
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> |
bsdf2klems(1), icalc(1), genBSDF(1), pabopto2bsdf(1), pabopto2xyz(1), |
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> |
pkgBSDF(1), rcontrib(1), rfluxmtx(1), wrapBSDF(1) |
