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
#	User	Rev	Content
1	greg	1.12	.\" RCSid "$Id: rtcontrib.1,v 1.11 2005/07/23 19:53:36 greg Exp $"
2	greg	1.3	.TH RTCONTRIB 1 5/25/05 RADIANCE
3	greg	1.1	.SH NAME
4	greg	1.5	rtcontrib - compute contribution coefficients in a RADIANCE scene
5	greg	1.1	.SH SYNOPSIS
6			.B rtcontrib
7			[
8			.B "\-n nprocs"
9			][
10	greg	1.8	.B \-r
11			][
12	greg	1.1	.B "\-e expr"
13			][
14			.B "\-f source"
15			][
16	greg	1.7	.B "\-o ospec"
17	greg	1.1	][
18			.B "\-b binv"
19	greg	1.12	][
20			.B "\-bn nbins"
21	greg	1.1	]
22	greg	1.9	{
23			.B "\-m mod \| \-M file"
24			}
25			..
26	greg	1.1	[
27			.B $EVAR
28			]
29			[
30			.B @file
31			]
32			[
33			rtrace options
34			]
35			.B octree
36	greg	1.4	.br
37			.B "rtcontrib [ options ] \-defaults"
38	greg	1.1	.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	greg	1.2	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	greg	1.9	A modifier list may also be read from a file using the
48			.I \-M
49			option.
50	greg	1.10	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	greg	1.9	.PP
55	greg	1.3	The output of
56			.I rtcontrib
57			has many potential uses.
58			Source contributions can be used as components in linear combination to
59	greg	1.1	reproduce any desired variation, e.g., simulating lighting controls or
60			changing sky conditions via daylight coefficients.
61			More generally,
62			.I rtcontrib
63	greg	1.3	can be used to compute arbitrary input-output relationships in optical
64			systems, such as luminaires, light pipes, and shading devices.
65	greg	1.1	.PP
66	greg	1.2	.I Rtcontrib
67			calls
68			.I rtrace(1)
69	greg	1.5	with the -oTW option to calculate the daughter ray
70			contributions for each input ray, and the output tallies
71	greg	1.7	are sent to one or more destinations according to the given
72	greg	1.1	.I \-o
73			specification.
74	greg	1.7	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	greg	1.8	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	greg	1.2	If an output specification contains a "%s" format, this will be
81	greg	1.1	replaced by the modifier name.
82			The
83			.I \-b
84			option may be used to further define
85	greg	1.2	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	greg	1.1	specification if present.
88	greg	1.3	The actual bin number is computed at run time based on ray direction
89			and surface intersection, as described below.
90	greg	1.12	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	greg	1.1	The most recent
95	greg	1.12	.I \-b,
96			.I \-bn
97	greg	1.1	and
98			.I \-o
99	greg	1.2	options to the left of each
100	greg	1.1	.I \-m
101	greg	1.2	setting affect only that modifier.
102			(The ordering of other options is unimportant.)\0
103	greg	1.1	.PP
104	greg	1.2	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	greg	1.3	arguments and files read using the
116	greg	1.2	.I \-f
117	greg	1.3	option.
118			The computed bin value will be
119	greg	1.2	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	greg	1.3	The rules and predefined functions available for these expressions are
125			described in the
126			.I rcalc(1)
127			man page.
128	greg	1.6	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	greg	1.1	.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	greg	1.7	Concatenated data is also sent to a single destination (i.e., an initial
140	greg	1.2	.I \-o
141			specification without formatting strings).
142	greg	1.1	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	greg	1.2	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	greg	1.1	.PP
177			If the
178			.I \-n
179			option is specified with a value greater than 1, multiple
180	greg	1.2	.I rtrace
181	greg	1.1	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	greg	1.2	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	greg	1.1	.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	greg	1.2	.SH EXAMPLES
195			To compute the proportional contributions from sources modified
196			by "light1" vs. "light2" on a set of illuminance values:
197	greg	1.1	.IP "" .2i
198	greg	1.2	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	greg	1.1	.IP "" .2i
203	greg	1.2	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	greg	1.1	.IP "" .2i
210	greg	1.2	pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
211	greg	1.1	.PP
212	greg	1.2	To compute an array of illuminance contributions according to a Tregenza sky:
213			.IP "" .2i
214	greg	1.11	rtcontrib -I+ -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
215	greg	1.2	@render.opt -f tregenza.cal scene.oct < test.dat
216	greg	1.6	.SH ENVIRONMENT
217	greg	1.10	RAYPATH path to search for -f and -M files
218	greg	1.1	.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)