man/man1/rtcontrib.1

.\" RCSid "$Id: rtcontrib.1,v 1.11 2005/07/23 19:53:36 greg Exp $"
.TH RTCONTRIB 1 5/25/05 RADIANCE
.SH NAME
rtcontrib - compute contribution coefficients in a RADIANCE scene
.SH SYNOPSIS
.B rtcontrib
[
.B "\-n nprocs"
][
.B \-r
][
.B "\-e expr"
][
.B "\-f source"
][
.B "\-o ospec"
][
.B "\-b binv"
][
.B "\-bn nbins"
]
{
.B "\-m mod | \-M file"
}
..
[
.B $EVAR
]
[
.B @file
]
[
rtrace options
]
.B octree
.br
.B "rtcontrib [ options ] \-defaults"
.SH DESCRIPTION
.I Rtcontrib
computes ray contributions (i.e., color coefficients)
for objects whose modifiers are named in one or more
.I \-m
settings.
These modifiers are usually materials associated with
light sources or sky domes, and must directly modify some geometric
primitives to be considered in the output.
A modifier list may also be read from a file using the
.I \-M
option.
The RAYPATH environment variable determines directories to search for
this file.
(No search takes place if a file name begins with a '.', '/' or '~'
character.)\0
.PP
The output of
.I rtcontrib
has many potential uses.
Source contributions can be used as components in linear combination to
reproduce any desired variation, e.g., simulating lighting controls or
changing sky conditions via daylight coefficients.
More generally,
.I rtcontrib
can be used to compute arbitrary input-output relationships in optical
systems, such as luminaires, light pipes, and shading devices.
.PP
.I Rtcontrib
calls
.I rtrace(1)
with the -oTW option to calculate the daughter ray
contributions for each input ray, and the output tallies
are sent to one or more destinations according to the given
.I \-o
specification.
If a destination begins with an exclamation mark ('!'), then
a pipe is opened to a command and data is sent to its standard input.
Otherwise, the destination is treated as a file.
An existing file of the same name is clobbered, unless the
.I \-r
option is specified, in which case data recovery is attempted.
If an output specification contains a "%s" format, this will be
replaced by the modifier name.
The
.I \-b
option may be used to further define
a "bin number" within each object if finer resolution is needed, and
this will be applied to a "%d" format in the output file
specification if present.
The actual bin number is computed at run time based on ray direction
and surface intersection, as described below.
If the number of bins is known in advance, it should be specified with the
.I \-bn
option, especially for output files containing multiple bins.
Set this to 0 if the number of bins is unknown (the default).
The most recent
.I \-b,
.I \-bn
and
.I \-o
options to the left of each
.I \-m
setting affect only that modifier.
(The ordering of other options is unimportant.)\0
.PP
If a
.I \-b
expression is defined for a particular modifier,
the bin number will be evaluated at run time for each
ray contribution from
.I rtrace.
Specifically, each ray's world intersection point will be assigned to
the variables Px, Py, and Pz, and the normalized ray direction
will be assigned to Dx, Dy, and Dz.
These parameters may be combined with definitions given in
.I \-e
arguments and files read using the
.I \-f
option.
The computed bin value will be
rounded to the nearest whole number.
This mechanism allows the user to define precise regions or directions
they wish to accumulate, such as the Tregenza sky discretization,
which would be otherwise impossible to specify
as a set of RADIANCE primitives.
The rules and predefined functions available for these expressions are
described in the
.I rcalc(1)
man page.
Unlike
.I rcalc,
.I rtcontrib
will search the RADIANCE library directories for each file given in a
.I \-f
option.
.PP
If no
.I \-o
specification is given, results are written on the standard output in order
of modifier (as given on the command line) then bin number.
Concatenated data is also sent to a single destination (i.e., an initial
.I \-o
specification without formatting strings).
If a "%s" format appears but no "%d" in the
.I \-o
specification, then each modifier will have its own output file, with
multiple values per record in the case of a non-zero
.I \-b
definition.
If a "%d" format appears but no "%s", then each bin will get its own
output file, with modifiers output in order in each record.
For text output, each RGB coefficient triple is separated by a tab,
with a newline at the end of each ray record.
For binary output formats, there is no such delimiter to mark
the end of each record.
.PP
Input and output format defaults to plain text, where each ray's
origin and direction (6 real values) are given on input,
and one line is produced per output file per ray.
Alternative data representations may be specified by the
.I \-f[io]
option, which is described in the
.I rtrace
man page along with the associated
.I \-x
and
.I \-y
resolution settings.
In particular, the color ('c') output data representation
together with positive dimensions for
.I \-x
and
.I \-y
will produce an uncompressed RADIANCE picture,
suitable for manipulation with
.I pcomb(1)
and related tools.
.PP
If the
.I \-n
option is specified with a value greater than 1, multiple
.I rtrace
processes will be used to accelerate computation on a shared
memory machine.
Note that there is no benefit to using more processes
than there are local CPUs available to do the work, and the
.I rtcontrib
process itself may use a considerable amount of CPU time.
.PP
Options may be given on the command line and/or read from the
environment and/or read from a file.
A command argument beginning with a dollar sign ('$') is immediately
replaced by the contents of the given environment variable.
A command argument beginning with an at sign ('@') is immediately
replaced by the contents of the given file.
.SH EXAMPLES
To compute the proportional contributions from sources modified
by "light1" vs. "light2" on a set of illuminance values:
.IP "" .2i
rtcontrib -I+ @render.opt -o c_%s.dat -m light1 -m light2 scene.oct < test.dat
.PP
To generate a pair of images corresponding to these two lights'
contributions:
.IP "" .2i
vwrays -ff -x 1024 -y 1024 -vf best.vf |
rtcontrib -ffc `vwrays -d -x 1024 -y 1024 -vf best.vf`
@render.opt -o c_%s.pic -m light1 -m light2 scene.oct
.PP
These images may then be recombined using the desired outputs
of light1 and light2:
.IP "" .2i
pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
.PP
To compute an array of illuminance contributions according to a Tregenza sky:
.IP "" .2i
rtcontrib -I+ -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
@render.opt -f tregenza.cal scene.oct < test.dat
.SH ENVIRONMENT
RAYPATH         path to search for -f and -M files
.SH AUTHOR
Greg Ward
.SH "SEE ALSO"
cnt(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
rcalc(1), rpict(1), rtrace(1), vwrays(1), ximage(1)
Revision:	1.12
Committed:	Thu Oct 6 05:49:44 2005 UTC (18 years, 7 months ago) by greg
Branch:	MAIN
Changes since 1.11:	+9 -2 lines
Log Message:	Extensive changes to support rtcontrib -bn option and fix -r problems
#	Content
1	.\" RCSid "$Id: rtcontrib.1,v 1.11 2005/07/23 19:53:36 greg Exp $"
2	.TH RTCONTRIB 1 5/25/05 RADIANCE
3	.SH NAME
4	rtcontrib - compute contribution coefficients in a RADIANCE scene
5	.SH SYNOPSIS
6	.B rtcontrib
7	[
8	.B "\-n nprocs"
9	][
10	.B \-r
11	][
12	.B "\-e expr"
13	][
14	.B "\-f source"
15	][
16	.B "\-o ospec"
17	][
18	.B "\-b binv"
19	][
20	.B "\-bn nbins"
21	]
22	{
23	.B "\-m mod \| \-M file"
24	}
25	..
26	[
27	.B $EVAR
28	]
29	[
30	.B @file
31	]
32	[
33	rtrace options
34	]
35	.B octree
36	.br
37	.B "rtcontrib [ options ] \-defaults"
38	.SH DESCRIPTION
39	.I Rtcontrib
40	computes ray contributions (i.e., color coefficients)
41	for objects whose modifiers are named in one or more
42	.I \-m
43	settings.
44	These modifiers are usually materials associated with
45	light sources or sky domes, and must directly modify some geometric
46	primitives to be considered in the output.
47	A modifier list may also be read from a file using the
48	.I \-M
49	option.
50	The RAYPATH environment variable determines directories to search for
51	this file.
52	(No search takes place if a file name begins with a '.', '/' or '~'
53	character.)\0
54	.PP
55	The output of
56	.I rtcontrib
57	has many potential uses.
58	Source contributions can be used as components in linear combination to
59	reproduce any desired variation, e.g., simulating lighting controls or
60	changing sky conditions via daylight coefficients.
61	More generally,
62	.I rtcontrib
63	can be used to compute arbitrary input-output relationships in optical
64	systems, such as luminaires, light pipes, and shading devices.
65	.PP
66	.I Rtcontrib
67	calls
68	.I rtrace(1)
69	with the -oTW option to calculate the daughter ray
70	contributions for each input ray, and the output tallies
71	are sent to one or more destinations according to the given
72	.I \-o
73	specification.
74	If a destination begins with an exclamation mark ('!'), then
75	a pipe is opened to a command and data is sent to its standard input.
76	Otherwise, the destination is treated as a file.
77	An existing file of the same name is clobbered, unless the
78	.I \-r
79	option is specified, in which case data recovery is attempted.
80	If an output specification contains a "%s" format, this will be
81	replaced by the modifier name.
82	The
83	.I \-b
84	option may be used to further define
85	a "bin number" within each object if finer resolution is needed, and
86	this will be applied to a "%d" format in the output file
87	specification if present.
88	The actual bin number is computed at run time based on ray direction
89	and surface intersection, as described below.
90	If the number of bins is known in advance, it should be specified with the
91	.I \-bn
92	option, especially for output files containing multiple bins.
93	Set this to 0 if the number of bins is unknown (the default).
94	The most recent
95	.I \-b,
96	.I \-bn
97	and
98	.I \-o
99	options to the left of each
100	.I \-m
101	setting affect only that modifier.
102	(The ordering of other options is unimportant.)\0
103	.PP
104	If a
105	.I \-b
106	expression is defined for a particular modifier,
107	the bin number will be evaluated at run time for each
108	ray contribution from
109	.I rtrace.
110	Specifically, each ray's world intersection point will be assigned to
111	the variables Px, Py, and Pz, and the normalized ray direction
112	will be assigned to Dx, Dy, and Dz.
113	These parameters may be combined with definitions given in
114	.I \-e
115	arguments and files read using the
116	.I \-f
117	option.
118	The computed bin value will be
119	rounded to the nearest whole number.
120	This mechanism allows the user to define precise regions or directions
121	they wish to accumulate, such as the Tregenza sky discretization,
122	which would be otherwise impossible to specify
123	as a set of RADIANCE primitives.
124	The rules and predefined functions available for these expressions are
125	described in the
126	.I rcalc(1)
127	man page.
128	Unlike
129	.I rcalc,
130	.I rtcontrib
131	will search the RADIANCE library directories for each file given in a
132	.I \-f
133	option.
134	.PP
135	If no
136	.I \-o
137	specification is given, results are written on the standard output in order
138	of modifier (as given on the command line) then bin number.
139	Concatenated data is also sent to a single destination (i.e., an initial
140	.I \-o
141	specification without formatting strings).
142	If a "%s" format appears but no "%d" in the
143	.I \-o
144	specification, then each modifier will have its own output file, with
145	multiple values per record in the case of a non-zero
146	.I \-b
147	definition.
148	If a "%d" format appears but no "%s", then each bin will get its own
149	output file, with modifiers output in order in each record.
150	For text output, each RGB coefficient triple is separated by a tab,
151	with a newline at the end of each ray record.
152	For binary output formats, there is no such delimiter to mark
153	the end of each record.
154	.PP
155	Input and output format defaults to plain text, where each ray's
156	origin and direction (6 real values) are given on input,
157	and one line is produced per output file per ray.
158	Alternative data representations may be specified by the
159	.I \-f[io]
160	option, which is described in the
161	.I rtrace
162	man page along with the associated
163	.I \-x
164	and
165	.I \-y
166	resolution settings.
167	In particular, the color ('c') output data representation
168	together with positive dimensions for
169	.I \-x
170	and
171	.I \-y
172	will produce an uncompressed RADIANCE picture,
173	suitable for manipulation with
174	.I pcomb(1)
175	and related tools.
176	.PP
177	If the
178	.I \-n
179	option is specified with a value greater than 1, multiple
180	.I rtrace
181	processes will be used to accelerate computation on a shared
182	memory machine.
183	Note that there is no benefit to using more processes
184	than there are local CPUs available to do the work, and the
185	.I rtcontrib
186	process itself may use a considerable amount of CPU time.
187	.PP
188	Options may be given on the command line and/or read from the
189	environment and/or read from a file.
190	A command argument beginning with a dollar sign ('$') is immediately
191	replaced by the contents of the given environment variable.
192	A command argument beginning with an at sign ('@') is immediately
193	replaced by the contents of the given file.
194	.SH EXAMPLES
195	To compute the proportional contributions from sources modified
196	by "light1" vs. "light2" on a set of illuminance values:
197	.IP "" .2i
198	rtcontrib -I+ @render.opt -o c_%s.dat -m light1 -m light2 scene.oct < test.dat
199	.PP
200	To generate a pair of images corresponding to these two lights'
201	contributions:
202	.IP "" .2i
203	vwrays -ff -x 1024 -y 1024 -vf best.vf \|
204	rtcontrib -ffc `vwrays -d -x 1024 -y 1024 -vf best.vf`
205	@render.opt -o c_%s.pic -m light1 -m light2 scene.oct
206	.PP
207	These images may then be recombined using the desired outputs
208	of light1 and light2:
209	.IP "" .2i
210	pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
211	.PP
212	To compute an array of illuminance contributions according to a Tregenza sky:
213	.IP "" .2i
214	rtcontrib -I+ -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
215	@render.opt -f tregenza.cal scene.oct < test.dat
216	.SH ENVIRONMENT
217	RAYPATH path to search for -f and -M files
218	.SH AUTHOR
219	Greg Ward
220	.SH "SEE ALSO"
221	cnt(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
222	rcalc(1), rpict(1), rtrace(1), vwrays(1), ximage(1)