man/man1/rfluxmtx.1

.\" RCSid "$Id: rfluxmtx.1,v 1.5 2014/08/29 08:33:34 greg Exp $"
.TH RFLUXMTX 1 07/22/14 RADIANCE
.SH NAME
rfluxmtx - compute flux transfer matrix(es) for RADIANCE scene
.SH SYNOPSIS
.B rfluxmtx
[
.B \-v
][
.B "rcontrib options"
]
.B "{ sender.rad | - }"
.B receivers.rad
.B "[ -i system.oct ]"
.B "[ system.rad .. ]"
.SH DESCRIPTION
.I Rfluxmtx
samples rays uniformly over the surface given in
.I sender.rad
and records rays arriving at surfaces in the file
.I receivers.rad,
producing a flux transfer matrix per receiver.
A system octree to which the receivers will be appended may be given with a
.I \-i
option following the receiver file.
Additional system surfaces may be given in one or more
.I system.rad
files, which are compiled before the receiver file into an octree sent to the
.I rcontrib(1)
program to do the actual work.
If a single hyphen ('-') is given in place of the sender file, then
.I rfluxmtx
passes ray samples from its standard input directly to
.I rcontrib
without interpretation.
By default, all resulting matrix data are interleaved and sent to the standard output
in ASCII format, but this behavior is typically overridden using inline options
as described below.
.PP
The
.I \-v
option turns on verbose reporting for the number of samples and the executed
.I rcontrib
command.
All other supported options are passed on to
.I rcontrib(1).
However, the
.I \-f,
.I \-e,
.I \-p,
.I \-b,
.I \-bn,
.I \-m,
and
.I \-M
options are controlled by
.I rfluxmtx
and may not be set by the user.
Also, the
.I \-x,
.I \-y,
and
.I \-ld
options are ignored unless
.I rfluxmtx
is invoked in the pass-through mode,
in which case they may be needed to generate RADIANCE views from
.I vwrays(1).
The sample count, unless set by the
.I \-c
option, defaults to 10000 when a sender file is given, or to 1 for pass-through mode.
.SH VARIABLES
The sender and receiver scene files given to
.I rfluxmtx
contain controlling parameters in special comments of the form:
.nf

        #@rfluxmtx variable=value ..

.fi
At minimum, both sender and receiver must specify one of the
hemisphere sampling types, and there must be at least
one surface in each file.
.TP 10n
.BI h =u
Set hemisphere sampling to "uniform," meaning a single bin
of (cosine-distributed) samples.
In the case of distant "source" primitives, this is the only
sampling method that supports arbitrary receiver sizes.
The other methods below require a full hemispherical source.
.TP
.BI h =kf
Divide the hemisphere using the LBNL/Klems "full" sampling basis.
.TP
.BI h =kh
Divide the hemisphere using the LBNL/Klems "half" sampling basis.
.TP
.BI h =kq
Divide the hemisphere using the LBNL/Klems "quarter" sampling basis.
.TP
.BI h =rN
Divide the hemisphere using Reinhart's substructuring of the Tregenza
sky pattern with
.I N
divisions in each dimension.
If it is not given,
.I N
defaults to 1, which is just the Tregenza sky.
.TP
.BI h =scN
Subdivide the hemisphere using the Shirley-Chiu square-to-disk mapping with an
.I NxN
grid over the square.
.TP
.BI u =[-]{X|Y|Z|ux,uy,uz}
Orient the "up" direction for the hemisphere using the indicated axis or direction
vector.
.TP
.BI o =output.mtx
Send the matrix data for this receiver to the indicated output file.
The file format will be determined by the command-line
.I \-fio
option and will include an information header unless the
.I \-h
option was used to turn headers off.
(The output file specification is ignored for senders.)\0
.PP
In normal execution, only a single sender surface is sampled, but it may be
comprised of any number of subsurfaces, as in a triangle mesh or similar.
The surface normal will be computed as the average of all the constituent
subsurfaces.
The subsurfaces themselves must be planar, thus only
.I polygon
and
.I ring
surface primitives are supported.
Other primitives will be silently ignored and will have no effect on the calculation.
.PP
In the receiver file, the
.I source
primitive is supported as well, and multiple receivers (and multiple output
matrices) are identified by different modifier names.
Though it may be counter-intuitive, receivers are often light sources,
since samples end up there in a backwards ray-tracing system such as RADIANCE.
When using local geometry, the overall aperture shape should be close to flat.
Large displacements may give rise to errors due to a convex receiver's
larger profile at low angles of incidence.
.PP
Rays always emanate from the back side of the sender surface and arrive at the
front side of receiver surfaces.
In this way, a receiver surface may be reused as a sender in a subsequent
.I rfluxmtx
calculation and the resulting matrices will concatenate properly.
(Note that it is important to keep receiver surfaces together, otherwise a
"duplicate modifier" error will result.)\0
.SH EXAMPLES
To generate a flux transfer matrix connecting input and output apertures
on a light pipe:
.IP "" .3i
rfluxmtx int_aperture.rad ext_aperture.rad lpipe.rad > lpipe.mtx
.SH AUTHOR
Greg Ward
.SH "SEE ALSO"
genBSDF(1), getinfo(1), rcalc(1), rcollate(1), rcontrib(1), rmtxop(1),
vwrays(1), wrapBSDF(1)
Revision:	1.6
Committed:	Fri Feb 20 18:26:08 2015 UTC (10 years, 8 months ago) by greg
Branch:	MAIN
Changes since 1.5:	+3 -2 lines
Log Message:	Created wrapBSDF tool and major overhaul of genBSDF to use it with rfluxmtx
#	User	Rev	Content
1	greg	1.6	.\" RCSid "$Id: rfluxmtx.1,v 1.5 2014/08/29 08:33:34 greg Exp $"
2	greg	1.1	.TH RFLUXMTX 1 07/22/14 RADIANCE
3			.SH NAME
4			rfluxmtx - compute flux transfer matrix(es) for RADIANCE scene
5			.SH SYNOPSIS
6			.B rfluxmtx
7			[
8			.B \-v
9			][
10			.B "rcontrib options"
11			]
12			.B "{ sender.rad \| - }"
13			.B receivers.rad
14	greg	1.4	.B "[ -i system.oct ]"
15			.B "[ system.rad .. ]"
16	greg	1.1	.SH DESCRIPTION
17			.I Rfluxmtx
18			samples rays uniformly over the surface given in
19			.I sender.rad
20			and records rays arriving at surfaces in the file
21			.I receivers.rad,
22			producing a flux transfer matrix per receiver.
23	greg	1.4	A system octree to which the receivers will be appended may be given with a
24			.I \-i
25			option following the receiver file.
26			Additional system surfaces may be given in one or more
27			.I system.rad
28			files, which are compiled before the receiver file into an octree sent to the
29	greg	1.1	.I rcontrib(1)
30			program to do the actual work.
31			If a single hyphen ('-') is given in place of the sender file, then
32			.I rfluxmtx
33			passes ray samples from its standard input directly to
34			.I rcontrib
35			without interpretation.
36			By default, all resulting matrix data are interleaved and sent to the standard output
37			in ASCII format, but this behavior is typically overridden using inline options
38			as described below.
39			.PP
40			The
41			.I \-v
42			option turns on verbose reporting for the number of samples and the executed
43			.I rcontrib
44			command.
45			All other supported options are passed on to
46			.I rcontrib(1).
47			However, the
48			.I \-f,
49			.I \-e,
50			.I \-p,
51			.I \-b,
52			.I \-bn,
53			.I \-m,
54			and
55			.I \-M
56			options are controlled by
57			.I rfluxmtx
58			and may not be set by the user.
59			Also, the
60			.I \-x,
61			.I \-y,
62			and
63			.I \-ld
64			options are ignored unless
65			.I rfluxmtx
66			is invoked in the pass-through mode,
67			in which case they may be needed to generate RADIANCE views from
68			.I vwrays(1).
69			The sample count, unless set by the
70			.I \-c
71	greg	1.2	option, defaults to 10000 when a sender file is given, or to 1 for pass-through mode.
72	greg	1.1	.SH VARIABLES
73			The sender and receiver scene files given to
74			.I rfluxmtx
75	greg	1.3	contain controlling parameters in special comments of the form:
76	greg	1.1	.nf
77
78			#@rfluxmtx variable=value ..
79
80			.fi
81			At minimum, both sender and receiver must specify one of the
82			hemisphere sampling types, and there must be at least
83			one surface in each file.
84			.TP 10n
85			.BI h =u
86			Set hemisphere sampling to "uniform," meaning a single bin
87			of (cosine-distributed) samples.
88	greg	1.3	In the case of distant "source" primitives, this is the only
89	greg	1.1	sampling method that supports arbitrary receiver sizes.
90			The other methods below require a full hemispherical source.
91			.TP
92			.BI h =kf
93			Divide the hemisphere using the LBNL/Klems "full" sampling basis.
94			.TP
95			.BI h =kh
96			Divide the hemisphere using the LBNL/Klems "half" sampling basis.
97			.TP
98			.BI h =kq
99			Divide the hemisphere using the LBNL/Klems "quarter" sampling basis.
100			.TP
101			.BI h =rN
102			Divide the hemisphere using Reinhart's substructuring of the Tregenza
103			sky pattern with
104			.I N
105			divisions in each dimension.
106			If it is not given,
107			.I N
108			defaults to 1, which is just the Tregenza sky.
109			.TP
110			.BI h =scN
111			Subdivide the hemisphere using the Shirley-Chiu square-to-disk mapping with an
112			.I NxN
113			grid over the square.
114			.TP
115			.BI u =[-]{X\|Y\|Z\|ux,uy,uz}
116			Orient the "up" direction for the hemisphere using the indicated axis or direction
117			vector.
118			.TP
119			.BI o =output.mtx
120			Send the matrix data for this receiver to the indicated output file.
121			The file format will be determined by the command-line
122			.I \-fio
123			option and will include an information header unless the
124			.I \-h
125			option was used to turn headers off.
126			(The output file specification is ignored for senders.)\0
127			.PP
128			In normal execution, only a single sender surface is sampled, but it may be
129			comprised of any number of subsurfaces, as in a triangle mesh or similar.
130			The surface normal will be computed as the average of all the constituent
131			subsurfaces.
132	greg	1.2	The subsurfaces themselves must be planar, thus only
133	greg	1.1	.I polygon
134			and
135			.I ring
136			surface primitives are supported.
137			Other primitives will be silently ignored and will have no effect on the calculation.
138			.PP
139			In the receiver file, the
140			.I source
141			primitive is supported as well, and multiple receivers (and multiple output
142			matrices) are identified by different modifier names.
143			Though it may be counter-intuitive, receivers are often light sources,
144			since samples end up there in a backwards ray-tracing system such as RADIANCE.
145	greg	1.2	When using local geometry, the overall aperture shape should be close to flat.
146			Large displacements may give rise to errors due to a convex receiver's
147			larger profile at low angles of incidence.
148	greg	1.1	.PP
149	greg	1.3	Rays always emanate from the back side of the sender surface and arrive at the
150	greg	1.1	front side of receiver surfaces.
151			In this way, a receiver surface may be reused as a sender in a subsequent
152			.I rfluxmtx
153			calculation and the resulting matrices will concatenate properly.
154			(Note that it is important to keep receiver surfaces together, otherwise a
155			"duplicate modifier" error will result.)\0
156			.SH EXAMPLES
157			To generate a flux transfer matrix connecting input and output apertures
158			on a light pipe:
159			.IP "" .3i
160	greg	1.5	rfluxmtx int_aperture.rad ext_aperture.rad lpipe.rad > lpipe.mtx
161	greg	1.1	.SH AUTHOR
162			Greg Ward
163			.SH "SEE ALSO"
164	greg	1.6	genBSDF(1), getinfo(1), rcalc(1), rcollate(1), rcontrib(1), rmtxop(1),
165			vwrays(1), wrapBSDF(1)