man/man1/rtcontrib.1

.\" RCSid "$Id: rtcontrib.1,v 1.8 2005/06/09 17:27:27 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 "\-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.
.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.
The most recent
.I \-b
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.
(No search takes place if a file name begins with a '.', '/' or '~'
character.)\0
.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 -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 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:	1.9
Committed:	Fri Jun 10 16:42:10 2005 UTC (18 years, 11 months ago) by greg
Branch:	MAIN
Changes since 1.8:	+9 -2 lines
Log Message:	Added rtcontrib -M option to read modifier list from a file
#	User	Rev	Content
1	greg	1.9	.\" RCSid "$Id: rtcontrib.1,v 1.8 2005/06/09 17:27:27 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			]
20	greg	1.9	{
21			.B "\-m mod \| \-M file"
22			}
23			..
24	greg	1.1	[
25			.B $EVAR
26			]
27			[
28			.B @file
29			]
30			[
31			rtrace options
32			]
33			.B octree
34	greg	1.4	.br
35			.B "rtcontrib [ options ] \-defaults"
36	greg	1.1	.SH DESCRIPTION
37			.I Rtcontrib
38			computes ray contributions (i.e., color coefficients)
39			for objects whose modifiers are named in one or more
40			.I \-m
41			settings.
42	greg	1.2	These modifiers are usually materials associated with
43			light sources or sky domes, and must directly modify some geometric
44			primitives to be considered in the output.
45	greg	1.9	A modifier list may also be read from a file using the
46			.I \-M
47			option.
48			.PP
49	greg	1.3	The output of
50			.I rtcontrib
51			has many potential uses.
52			Source contributions can be used as components in linear combination to
53	greg	1.1	reproduce any desired variation, e.g., simulating lighting controls or
54			changing sky conditions via daylight coefficients.
55			More generally,
56			.I rtcontrib
57	greg	1.3	can be used to compute arbitrary input-output relationships in optical
58			systems, such as luminaires, light pipes, and shading devices.
59	greg	1.1	.PP
60	greg	1.2	.I Rtcontrib
61			calls
62			.I rtrace(1)
63	greg	1.5	with the -oTW option to calculate the daughter ray
64			contributions for each input ray, and the output tallies
65	greg	1.7	are sent to one or more destinations according to the given
66	greg	1.1	.I \-o
67			specification.
68	greg	1.7	If a destination begins with an exclamation mark ('!'), then
69			a pipe is opened to a command and data is sent to its standard input.
70			Otherwise, the destination is treated as a file.
71	greg	1.8	An existing file of the same name is clobbered, unless the
72			.I \-r
73			option is specified, in which case data recovery is attempted.
74	greg	1.2	If an output specification contains a "%s" format, this will be
75	greg	1.1	replaced by the modifier name.
76			The
77			.I \-b
78			option may be used to further define
79	greg	1.2	a "bin number" within each object if finer resolution is needed, and
80			this will be applied to a "%d" format in the output file
81	greg	1.1	specification if present.
82	greg	1.3	The actual bin number is computed at run time based on ray direction
83			and surface intersection, as described below.
84	greg	1.1	The most recent
85			.I \-b
86			and
87			.I \-o
88	greg	1.2	options to the left of each
89	greg	1.1	.I \-m
90	greg	1.2	setting affect only that modifier.
91			(The ordering of other options is unimportant.)\0
92	greg	1.1	.PP
93	greg	1.2	If a
94			.I \-b
95			expression is defined for a particular modifier,
96			the bin number will be evaluated at run time for each
97			ray contribution from
98			.I rtrace.
99			Specifically, each ray's world intersection point will be assigned to
100			the variables Px, Py, and Pz, and the normalized ray direction
101			will be assigned to Dx, Dy, and Dz.
102			These parameters may be combined with definitions given in
103			.I \-e
104	greg	1.3	arguments and files read using the
105	greg	1.2	.I \-f
106	greg	1.3	option.
107			The computed bin value will be
108	greg	1.2	rounded to the nearest whole number.
109			This mechanism allows the user to define precise regions or directions
110			they wish to accumulate, such as the Tregenza sky discretization,
111			which would be otherwise impossible to specify
112			as a set of RADIANCE primitives.
113	greg	1.3	The rules and predefined functions available for these expressions are
114			described in the
115			.I rcalc(1)
116			man page.
117	greg	1.6	Unlike
118			.I rcalc,
119			.I rtcontrib
120			will search the RADIANCE library directories for each file given in a
121			.I \-f
122			option.
123			(No search takes place if a file name begins with a '.', '/' or '~'
124			character.)\0
125	greg	1.1	.PP
126			If no
127			.I \-o
128			specification is given, results are written on the standard output in order
129			of modifier (as given on the command line) then bin number.
130	greg	1.7	Concatenated data is also sent to a single destination (i.e., an initial
131	greg	1.2	.I \-o
132			specification without formatting strings).
133	greg	1.1	If a "%s" format appears but no "%d" in the
134			.I \-o
135			specification, then each modifier will have its own output file, with
136			multiple values per record in the case of a non-zero
137			.I \-b
138			definition.
139			If a "%d" format appears but no "%s", then each bin will get its own
140			output file, with modifiers output in order in each record.
141			For text output, each RGB coefficient triple is separated by a tab,
142			with a newline at the end of each ray record.
143			For binary output formats, there is no such delimiter to mark
144			the end of each record.
145			.PP
146	greg	1.2	Input and output format defaults to plain text, where each ray's
147			origin and direction (6 real values) are given on input,
148			and one line is produced per output file per ray.
149			Alternative data representations may be specified by the
150			.I \-f[io]
151			option, which is described in the
152			.I rtrace
153			man page along with the associated
154			.I \-x
155			and
156			.I \-y
157			resolution settings.
158			In particular, the color ('c') output data representation
159			together with positive dimensions for
160			.I \-x
161			and
162			.I \-y
163			will produce an uncompressed RADIANCE picture,
164			suitable for manipulation with
165			.I pcomb(1)
166			and related tools.
167	greg	1.1	.PP
168			If the
169			.I \-n
170			option is specified with a value greater than 1, multiple
171	greg	1.2	.I rtrace
172	greg	1.1	processes will be used to accelerate computation on a shared
173			memory machine.
174			Note that there is no benefit to using more processes
175	greg	1.2	than there are local CPUs available to do the work, and the
176			.I rtcontrib
177			process itself may use a considerable amount of CPU time.
178	greg	1.1	.PP
179			Options may be given on the command line and/or read from the
180			environment and/or read from a file.
181			A command argument beginning with a dollar sign ('$') is immediately
182			replaced by the contents of the given environment variable.
183			A command argument beginning with an at sign ('@') is immediately
184			replaced by the contents of the given file.
185	greg	1.2	.SH EXAMPLES
186			To compute the proportional contributions from sources modified
187			by "light1" vs. "light2" on a set of illuminance values:
188	greg	1.1	.IP "" .2i
189	greg	1.2	rtcontrib -I+ @render.opt -o c_%s.dat -m light1 -m light2 scene.oct < test.dat
190			.PP
191			To generate a pair of images corresponding to these two lights'
192			contributions:
193	greg	1.1	.IP "" .2i
194	greg	1.2	vwrays -ff -x 1024 -y 1024 -vf best.vf \|
195			rtcontrib -ffc `vwrays -d -x 1024 -y 1024 -vf best.vf`
196			@render.opt -o c_%s.pic -m light1 -m light2 scene.oct
197			.PP
198			These images may then be recombined using the desired outputs
199			of light1 and light2:
200	greg	1.1	.IP "" .2i
201	greg	1.2	pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
202	greg	1.1	.PP
203	greg	1.2	To compute an array of illuminance contributions according to a Tregenza sky:
204			.IP "" .2i
205			rtcontrib -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
206			@render.opt -f tregenza.cal scene.oct < test.dat
207	greg	1.6	.SH ENVIRONMENT
208			RAYPATH path to search for -f files
209	greg	1.1	.SH AUTHOR
210			Greg Ward
211			.SH "SEE ALSO"
212			cnt(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
213			rcalc(1), rpict(1), rtrace(1), vwrays(1), ximage(1)