| 10 |
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.B "\-n nproc" |
| 11 |
|
][ |
| 12 |
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.B "\-s symmetry" |
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+ |
][ |
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+ |
.B "\-g angle | 'A'" |
| 15 |
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] |
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.B "meas1 meas2 .." |
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.SH DESCRIPTION |
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.I Pabopto2bsdf |
| 19 |
|
takes two or more pab-opto |
| 20 |
|
.I Mountain |
| 21 |
< |
files, each corresponding |
| 22 |
< |
to a different incident beam angle, and produces a |
| 23 |
< |
Scattering Interpolant Representation (SIR) |
| 21 |
> |
files, each nominally containing |
| 22 |
> |
different incident beam angles or sampling patterns, |
| 23 |
> |
and produces a Scattering Interpolant Representation (SIR) |
| 24 |
|
on the standard output for further processing. |
| 25 |
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The binary SIR contains a Radial Basis Function fitting |
| 26 |
|
each incident BSDF data file |
| 27 |
< |
and a "transport plan" between neighboring RBF |
| 27 |
> |
and a "transport plan" matrix for each pair of neighboring RBF |
| 28 |
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directions in a spherical Delaunay mesh. |
| 29 |
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.PP |
| 30 |
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The SIR provides a complete 4-dimensional |
| 38 |
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front reflection, back reflection, front transmission, |
| 39 |
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and back transmission. |
| 40 |
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Theoretically, only one transmission direction is required, |
| 41 |
< |
but it is often safest to measure both if they |
| 41 |
> |
but it is often safest to measure both if they are to |
| 42 |
|
be used in a simulation. |
| 43 |
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(See |
| 44 |
|
.I bsdf2klems(1) |
| 56 |
|
.I \-t |
| 57 |
|
option reverses the assumed sample orientation front-to-back, |
| 58 |
|
and is discussed below under the "#intheta" header entry. |
| 59 |
+ |
.PP |
| 60 |
|
Multi-processing may be used to accelerate the program |
| 61 |
|
on systems that support it via the |
| 62 |
|
.I \-n |
| 99 |
|
.I \-s |
| 100 |
|
option must be specified if the default mirroring is not appropriate. |
| 101 |
|
.PP |
| 102 |
+ |
If a |
| 103 |
+ |
.I \-g |
| 104 |
+ |
option is present, it will cull scattered measurements that are nearer |
| 105 |
+ |
to grazing than the given angle in degrees. |
| 106 |
+ |
If the word "auto" (which can be abbreviated as 'a' or 'A') is given |
| 107 |
+ |
instead of an angle, then the near-grazing angle will be determined |
| 108 |
+ |
by the lowest incident angle measurement present in the input data. |
| 109 |
+ |
This is sometimes necessary to eliminate noise and edge effects that |
| 110 |
+ |
some measurements exhibit near grazing. |
| 111 |
+ |
.PP |
| 112 |
|
The |
| 113 |
|
.I Mountain |
| 114 |
< |
software operates the pg2 goniophotometer to |
| 115 |
< |
capture BSDF scattering data in separate text files for each incident |
| 116 |
< |
angle, beginning with a header |
| 114 |
> |
program, written by Peter Apian-Bennewitz, stores data taken by |
| 115 |
> |
his pg2 goniophotometer in separate |
| 116 |
> |
BSDF scattering files for each incident angle, beginning with a header |
| 117 |
|
whose lines each start with a pound sign ('#'). |
| 118 |
|
Some header settings require colons and others do not, as indicated below. |
| 119 |
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The |
| 123 |
|
.TP |
| 124 |
|
.BR #sample_name |
| 125 |
|
A double-quoted string containing the name associated with this sample. |
| 126 |
< |
If input files contain different sample names, the one read |
| 127 |
< |
will be the sample name passed to the SIR output. |
| 126 |
> |
If input files contain different sample names, the final sample name read |
| 127 |
> |
will be the one passed to the SIR output. |
| 128 |
|
.TP |
| 129 |
|
.BR #format: |
| 130 |
|
The data format, typically one of "theta phi DSF" or "theta phi BSDF". |
| 255 |
|
so theta=180 is the opposite side surface normal. |
| 256 |
|
This differs from the WINDOW, which use separate |
| 257 |
|
coordinate systems for the front and the back. |
| 258 |
< |
To confusing things further, notions of "front" and "back" are |
| 258 |
> |
To confuse things further, notions of "front" and "back" are |
| 259 |
|
opposite in WINDOW and RADIANCE. |
| 260 |
|
In RADIANCE, the normal of a window surface usually faces the |
| 261 |
< |
interior of a space. |
| 261 |
> |
interior of a space, where the WINDOW convention uses "FRONT" |
| 262 |
> |
for the exterior of a building. |
| 263 |
|
.PP |
| 264 |
|
In the |
| 265 |
|
.I genBSDF(1) |
| 266 |
|
utility, the world coordinate system follows trigonometric |
| 267 |
|
conventions with theta=0 aligning to the Z-axis, |
| 268 |
|
the X-axis matches (theta,phi)=(90,0), and the Y-axis |
| 269 |
< |
is has (theta,phi)=(90,90). |
| 269 |
> |
corresponds to (theta,phi)=(90,90). |
| 270 |
|
The latter is thought of as the "up" direction for the sample. |
| 271 |
|
This usually needs to be rotated into position, since most |
| 272 |
|
RADIANCE models use the Z-axis as the world "up" direction. |
| 274 |
|
Greg Ward |
| 275 |
|
.SH "SEE ALSO" |
| 276 |
|
bsdf2klems(1), bsdf2rad(1), bsdf2ttree(1), bsdfview(1), genBSDF(1), |
| 277 |
< |
pabopto2xyz(1) |
| 277 |
> |
pabopto2xyz(1) |
