man/man1/rfluxmtx.1

.\" RCSid "$Id: rfluxmtx.1,v 1.4 2014/08/06 00:59:53 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)
Revision:	1.5
Committed:	Fri Aug 29 08:33:34 2014 UTC (10 years, 8 months ago) by greg
Branch:	MAIN
CVS Tags:	rad4R2P2, rad4R2P1
Changes since 1.4:	+2 -2 lines
Log Message:	Fixed typos
#	Content
1	.\" RCSid "$Id: rfluxmtx.1,v 1.4 2014/08/06 00:59:53 greg Exp $"
2	.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	.B "[ -i system.oct ]"
15	.B "[ system.rad .. ]"
16	.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	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	.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	option, defaults to 10000 when a sender file is given, or to 1 for pass-through mode.
72	.SH VARIABLES
73	The sender and receiver scene files given to
74	.I rfluxmtx
75	contain controlling parameters in special comments of the form:
76	.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	In the case of distant "source" primitives, this is the only
89	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	The subsurfaces themselves must be planar, thus only
133	.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	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	.PP
149	Rays always emanate from the back side of the sender surface and arrive at the
150	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	rfluxmtx int_aperture.rad ext_aperture.rad lpipe.rad > lpipe.mtx
161	.SH AUTHOR
162	Greg Ward
163	.SH "SEE ALSO"
164	genBSDF(1), getinfo(1), rcalc(1), rcollate(1), rcontrib(1), rmtxop(1), vwrays(1)