man/man1/genBSDF.1

.\" RCSid $Id: genBSDF.1,v 1.4 2011/02/22 22:51:23 greg Exp $
.TH GENBSDF 1 9/3/2010 RADIANCE
.SH NAME
genBSDF - generate BSDF description from Radiance or MGF input
.SH SYNOPSIS
.B genBSDF
[
.B "\-c Nsamp"
][
.B "\-n Nproc"
][
.B "\-r 'rtcontrib opts...'"
][
.B "{+|-}forward"
][
.B "{+|-}backward"
][
.B "{+|-}mgf"
][
.B "{+|-}geom
][
.B "\-dim Xmin Xmax Ymin Ymax Zmin Zmax"
]
[
.B "geom .."
]
.SH DESCRIPTION
.I GenBSDF
computes a bidirectional scattering distribution function from
a Radiance or MGF scene description given on the input.
The program assumes the input is in Radiance format unless the
.I \+mgf
option is specified.
The output conforms to the LBNL Window 6 XML standard for BSDF data,
and will include an MGF representation of the input geometry if the
.I \+geom
option is given.
(This is the default, and may be switched off using
.I \-geom.)\0
.PP
Normally,
.I genBSDF
computes components needed by a backwards ray-tracing process,
.I \+backward.
If both forward and backward (front and back) distributions are needed, the
.I \+forward
option may be given.
To turn off backward components, use the
.I \-backward
option.
Computing both components takes about twice as long as one component.
.PP
The geometry must fit a rectangular profile, whose width is along the X-axis,
height is in the Y-axis, and depth is in the Z-axis.
The positive Z-axis points into the room, and the input geometry should
not extend into the room.
(I.e., it should not contain any positive Z values, since the putative 
emitting surface is assumed to lie at Z=0.)\0
The entire window system should be modeled, including sills and
edge geometry anticipated in the final installation, otherwise
accuracy will be impaired.
Similarly, materials in the description should be carefully measured.
.PP
Normally, the input geometry will be positioned according to its actual
bounding box, but this may be overridden with the
.I \-dim
option.
Use this in cases where the fenestration system is designed to fit a
smaller (or larger) opening or is offset somehow.
.PP
The variance in the results may be reduced by increasing the number of
samples per incident direction using the
.I \-c
option.
This value defaults to 1000 samples distributed over the incoming plane
for each of the 145 Klems hemisphere directions.
.PP
In some cases, the processing time may be reduced by the
.I \-n
option, which specifies the number of simultaneous
.I rtrace(1)
processes to run in
.I rtcontrib(1).
The
.I \-r
option may be used to specify a set of quoted arguments to be
included on the
.I rtcontrib
command line.
.SH EXAMPLE
To create a BSDF description including geometry from a set of venetian blinds:
.IP "" .2i
genblinds blind_white blind1 .07 3 1.5 30 40 | xform -rz -90 -rx 90 > blind1.rad
.br
genBSDF -r @rtc.opt blind_white.mat glazing.rad blind1.rad > blind1.xml
.SH AUTHOR
Greg Ward
.SH "SEE ALSO"
dctimestep(1), genklemsamp(1), genskyvec(1), mkillum(1), rtcontrib(1), rtrace(1)
Revision:	1.5
Committed:	Fri May 6 23:58:09 2011 UTC (14 years, 6 months ago) by greg
Branch:	MAIN
Changes since 1.4:	+1 -7 lines
Log Message:	Removed outdated note
#	User	Rev	Content
1	greg	1.5	.\" RCSid $Id: genBSDF.1,v 1.4 2011/02/22 22:51:23 greg Exp $
2	greg	1.1	.TH GENBSDF 1 9/3/2010 RADIANCE
3			.SH NAME
4			genBSDF - generate BSDF description from Radiance or MGF input
5			.SH SYNOPSIS
6			.B genBSDF
7			[
8			.B "\-c Nsamp"
9			][
10			.B "\-n Nproc"
11			][
12	greg	1.4	.B "\-r 'rtcontrib opts...'"
13			][
14	greg	1.3	.B "{+\|-}forward"
15			][
16			.B "{+\|-}backward"
17			][
18	greg	1.1	.B "{+\|-}mgf"
19			][
20			.B "{+\|-}geom
21			][
22			.B "\-dim Xmin Xmax Ymin Ymax Zmin Zmax"
23			]
24			[
25			.B "geom .."
26			]
27			.SH DESCRIPTION
28			.I GenBSDF
29	greg	1.3	computes a bidirectional scattering distribution function from
30	greg	1.1	a Radiance or MGF scene description given on the input.
31			The program assumes the input is in Radiance format unless the
32			.I \+mgf
33			option is specified.
34			The output conforms to the LBNL Window 6 XML standard for BSDF data,
35			and will include an MGF representation of the input geometry if the
36			.I \+geom
37			option is given.
38	greg	1.3	(This is the default, and may be switched off using
39	greg	1.1	.I \-geom.)\0
40			.PP
41	greg	1.3	Normally,
42			.I genBSDF
43			computes components needed by a backwards ray-tracing process,
44			.I \+backward.
45			If both forward and backward (front and back) distributions are needed, the
46			.I \+forward
47			option may be given.
48			To turn off backward components, use the
49			.I \-backward
50			option.
51			Computing both components takes about twice as long as one component.
52			.PP
53	greg	1.1	The geometry must fit a rectangular profile, whose width is along the X-axis,
54			height is in the Y-axis, and depth is in the Z-axis.
55			The positive Z-axis points into the room, and the input geometry should
56			not extend into the room.
57			(I.e., it should not contain any positive Z values, since the putative
58			emitting surface is assumed to lie at Z=0.)\0
59			The entire window system should be modeled, including sills and
60			edge geometry anticipated in the final installation, otherwise
61			accuracy will be impaired.
62			Similarly, materials in the description should be carefully measured.
63			.PP
64			Normally, the input geometry will be positioned according to its actual
65			bounding box, but this may be overridden with the
66			.I \-dim
67			option.
68			Use this in cases where the fenestration system is designed to fit a
69			smaller (or larger) opening or is offset somehow.
70			.PP
71			The variance in the results may be reduced by increasing the number of
72			samples per incident direction using the
73			.I \-c
74			option.
75			This value defaults to 1000 samples distributed over the incoming plane
76			for each of the 145 Klems hemisphere directions.
77			.PP
78			In some cases, the processing time may be reduced by the
79			.I \-n
80			option, which specifies the number of simultaneous
81			.I rtrace(1)
82			processes to run in
83			.I rtcontrib(1).
84	greg	1.4	The
85			.I \-r
86			option may be used to specify a set of quoted arguments to be
87			included on the
88			.I rtcontrib
89			command line.
90	greg	1.1	.SH EXAMPLE
91			To create a BSDF description including geometry from a set of venetian blinds:
92			.IP "" .2i
93	greg	1.2	genblinds blind_white blind1 .07 3 1.5 30 40 \| xform -rz -90 -rx 90 > blind1.rad
94	greg	1.1	.br
95	greg	1.4	genBSDF -r @rtc.opt blind_white.mat glazing.rad blind1.rad > blind1.xml
96	greg	1.1	.SH AUTHOR
97			Greg Ward
98			.SH "SEE ALSO"
99			dctimestep(1), genklemsamp(1), genskyvec(1), mkillum(1), rtcontrib(1), rtrace(1)