man/man1/rtcontrib.1

.\" RCSid "$Id: rtcontrib.1,v 1.12 2005/10/06 05:49:44 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, and this is critical for output files containing multiple values
per record.
Since bin numbers start from 0, the bin count is always equal to
the last bin plus 1.
Set the this value to 0 if the bin count 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:	1.13
Committed:	Thu Oct 6 16:28:59 2005 UTC (18 years, 7 months ago) by greg
Branch:	MAIN
Changes since 1.12:	+6 -3 lines
Log Message:	Fixes in new rtcontrib -bn option
#	User	Rev	Content
1	greg	1.13	.\" RCSid "$Id: rtcontrib.1,v 1.12 2005/10/06 05:49:44 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	greg	1.13	option, and this is critical for output files containing multiple values
93			per record.
94			Since bin numbers start from 0, the bin count is always equal to
95			the last bin plus 1.
96			Set the this value to 0 if the bin count is unknown (the default).
97	greg	1.1	The most recent
98	greg	1.12	.I \-b,
99			.I \-bn
100	greg	1.1	and
101			.I \-o
102	greg	1.2	options to the left of each
103	greg	1.1	.I \-m
104	greg	1.2	setting affect only that modifier.
105			(The ordering of other options is unimportant.)\0
106	greg	1.1	.PP
107	greg	1.2	If a
108			.I \-b
109			expression is defined for a particular modifier,
110			the bin number will be evaluated at run time for each
111			ray contribution from
112			.I rtrace.
113			Specifically, each ray's world intersection point will be assigned to
114			the variables Px, Py, and Pz, and the normalized ray direction
115			will be assigned to Dx, Dy, and Dz.
116			These parameters may be combined with definitions given in
117			.I \-e
118	greg	1.3	arguments and files read using the
119	greg	1.2	.I \-f
120	greg	1.3	option.
121			The computed bin value will be
122	greg	1.2	rounded to the nearest whole number.
123			This mechanism allows the user to define precise regions or directions
124			they wish to accumulate, such as the Tregenza sky discretization,
125			which would be otherwise impossible to specify
126			as a set of RADIANCE primitives.
127	greg	1.3	The rules and predefined functions available for these expressions are
128			described in the
129			.I rcalc(1)
130			man page.
131	greg	1.6	Unlike
132			.I rcalc,
133			.I rtcontrib
134			will search the RADIANCE library directories for each file given in a
135			.I \-f
136			option.
137	greg	1.1	.PP
138			If no
139			.I \-o
140			specification is given, results are written on the standard output in order
141			of modifier (as given on the command line) then bin number.
142	greg	1.7	Concatenated data is also sent to a single destination (i.e., an initial
143	greg	1.2	.I \-o
144			specification without formatting strings).
145	greg	1.1	If a "%s" format appears but no "%d" in the
146			.I \-o
147			specification, then each modifier will have its own output file, with
148			multiple values per record in the case of a non-zero
149			.I \-b
150			definition.
151			If a "%d" format appears but no "%s", then each bin will get its own
152			output file, with modifiers output in order in each record.
153			For text output, each RGB coefficient triple is separated by a tab,
154			with a newline at the end of each ray record.
155			For binary output formats, there is no such delimiter to mark
156			the end of each record.
157			.PP
158	greg	1.2	Input and output format defaults to plain text, where each ray's
159			origin and direction (6 real values) are given on input,
160			and one line is produced per output file per ray.
161			Alternative data representations may be specified by the
162			.I \-f[io]
163			option, which is described in the
164			.I rtrace
165			man page along with the associated
166			.I \-x
167			and
168			.I \-y
169			resolution settings.
170			In particular, the color ('c') output data representation
171			together with positive dimensions for
172			.I \-x
173			and
174			.I \-y
175			will produce an uncompressed RADIANCE picture,
176			suitable for manipulation with
177			.I pcomb(1)
178			and related tools.
179	greg	1.1	.PP
180			If the
181			.I \-n
182			option is specified with a value greater than 1, multiple
183	greg	1.2	.I rtrace
184	greg	1.1	processes will be used to accelerate computation on a shared
185			memory machine.
186			Note that there is no benefit to using more processes
187	greg	1.2	than there are local CPUs available to do the work, and the
188			.I rtcontrib
189			process itself may use a considerable amount of CPU time.
190	greg	1.1	.PP
191			Options may be given on the command line and/or read from the
192			environment and/or read from a file.
193			A command argument beginning with a dollar sign ('$') is immediately
194			replaced by the contents of the given environment variable.
195			A command argument beginning with an at sign ('@') is immediately
196			replaced by the contents of the given file.
197	greg	1.2	.SH EXAMPLES
198			To compute the proportional contributions from sources modified
199			by "light1" vs. "light2" on a set of illuminance values:
200	greg	1.1	.IP "" .2i
201	greg	1.2	rtcontrib -I+ @render.opt -o c_%s.dat -m light1 -m light2 scene.oct < test.dat
202			.PP
203			To generate a pair of images corresponding to these two lights'
204			contributions:
205	greg	1.1	.IP "" .2i
206	greg	1.2	vwrays -ff -x 1024 -y 1024 -vf best.vf \|
207			rtcontrib -ffc `vwrays -d -x 1024 -y 1024 -vf best.vf`
208			@render.opt -o c_%s.pic -m light1 -m light2 scene.oct
209			.PP
210			These images may then be recombined using the desired outputs
211			of light1 and light2:
212	greg	1.1	.IP "" .2i
213	greg	1.2	pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
214	greg	1.1	.PP
215	greg	1.2	To compute an array of illuminance contributions according to a Tregenza sky:
216			.IP "" .2i
217	greg	1.11	rtcontrib -I+ -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
218	greg	1.2	@render.opt -f tregenza.cal scene.oct < test.dat
219	greg	1.6	.SH ENVIRONMENT
220	greg	1.10	RAYPATH path to search for -f and -M files
221	greg	1.1	.SH AUTHOR
222			Greg Ward
223			.SH "SEE ALSO"
224			cnt(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
225			rcalc(1), rpict(1), rtrace(1), vwrays(1), ximage(1)