man/man1/rtcontrib.1

.\" RCSid "$Id: rtcontrib.1,v 1.7 2005/06/02 04:47:26 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 .."
[
.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.
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:	1.8
Committed:	Thu Jun 9 17:27:27 2005 UTC (18 years, 11 months ago) by greg
Branch:	MAIN
Changes since 1.7:	+6 -2 lines
Log Message:	Implementaed rtcontrib -r (recover) option, added MODIFIER= + BIN= to header
#	User	Rev	Content
1	greg	1.8	.\" RCSid "$Id: rtcontrib.1,v 1.7 2005/06/02 04:47:26 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	1.2	.B "\-m mod .."
21	greg	1.1	[
22			.B $EVAR
23			]
24			[
25			.B @file
26			]
27			[
28			rtrace options
29			]
30			.B octree
31	greg	1.4	.br
32			.B "rtcontrib [ options ] \-defaults"
33	greg	1.1	.SH DESCRIPTION
34			.I Rtcontrib
35			computes ray contributions (i.e., color coefficients)
36			for objects whose modifiers are named in one or more
37			.I \-m
38			settings.
39	greg	1.2	These modifiers are usually materials associated with
40			light sources or sky domes, and must directly modify some geometric
41			primitives to be considered in the output.
42	greg	1.3	The output of
43			.I rtcontrib
44			has many potential uses.
45			Source contributions can be used as components in linear combination to
46	greg	1.1	reproduce any desired variation, e.g., simulating lighting controls or
47			changing sky conditions via daylight coefficients.
48			More generally,
49			.I rtcontrib
50	greg	1.3	can be used to compute arbitrary input-output relationships in optical
51			systems, such as luminaires, light pipes, and shading devices.
52	greg	1.1	.PP
53	greg	1.2	.I Rtcontrib
54			calls
55			.I rtrace(1)
56	greg	1.5	with the -oTW option to calculate the daughter ray
57			contributions for each input ray, and the output tallies
58	greg	1.7	are sent to one or more destinations according to the given
59	greg	1.1	.I \-o
60			specification.
61	greg	1.7	If a destination begins with an exclamation mark ('!'), then
62			a pipe is opened to a command and data is sent to its standard input.
63			Otherwise, the destination is treated as a file.
64	greg	1.8	An existing file of the same name is clobbered, unless the
65			.I \-r
66			option is specified, in which case data recovery is attempted.
67	greg	1.2	If an output specification contains a "%s" format, this will be
68	greg	1.1	replaced by the modifier name.
69			The
70			.I \-b
71			option may be used to further define
72	greg	1.2	a "bin number" within each object if finer resolution is needed, and
73			this will be applied to a "%d" format in the output file
74	greg	1.1	specification if present.
75	greg	1.3	The actual bin number is computed at run time based on ray direction
76			and surface intersection, as described below.
77	greg	1.1	The most recent
78			.I \-b
79			and
80			.I \-o
81	greg	1.2	options to the left of each
82	greg	1.1	.I \-m
83	greg	1.2	setting affect only that modifier.
84			(The ordering of other options is unimportant.)\0
85	greg	1.1	.PP
86	greg	1.2	If a
87			.I \-b
88			expression is defined for a particular modifier,
89			the bin number will be evaluated at run time for each
90			ray contribution from
91			.I rtrace.
92			Specifically, each ray's world intersection point will be assigned to
93			the variables Px, Py, and Pz, and the normalized ray direction
94			will be assigned to Dx, Dy, and Dz.
95			These parameters may be combined with definitions given in
96			.I \-e
97	greg	1.3	arguments and files read using the
98	greg	1.2	.I \-f
99	greg	1.3	option.
100			The computed bin value will be
101	greg	1.2	rounded to the nearest whole number.
102			This mechanism allows the user to define precise regions or directions
103			they wish to accumulate, such as the Tregenza sky discretization,
104			which would be otherwise impossible to specify
105			as a set of RADIANCE primitives.
106	greg	1.3	The rules and predefined functions available for these expressions are
107			described in the
108			.I rcalc(1)
109			man page.
110	greg	1.6	Unlike
111			.I rcalc,
112			.I rtcontrib
113			will search the RADIANCE library directories for each file given in a
114			.I \-f
115			option.
116			(No search takes place if a file name begins with a '.', '/' or '~'
117			character.)\0
118	greg	1.1	.PP
119			If no
120			.I \-o
121			specification is given, results are written on the standard output in order
122			of modifier (as given on the command line) then bin number.
123	greg	1.7	Concatenated data is also sent to a single destination (i.e., an initial
124	greg	1.2	.I \-o
125			specification without formatting strings).
126	greg	1.1	If a "%s" format appears but no "%d" in the
127			.I \-o
128			specification, then each modifier will have its own output file, with
129			multiple values per record in the case of a non-zero
130			.I \-b
131			definition.
132			If a "%d" format appears but no "%s", then each bin will get its own
133			output file, with modifiers output in order in each record.
134			For text output, each RGB coefficient triple is separated by a tab,
135			with a newline at the end of each ray record.
136			For binary output formats, there is no such delimiter to mark
137			the end of each record.
138			.PP
139	greg	1.2	Input and output format defaults to plain text, where each ray's
140			origin and direction (6 real values) are given on input,
141			and one line is produced per output file per ray.
142			Alternative data representations may be specified by the
143			.I \-f[io]
144			option, which is described in the
145			.I rtrace
146			man page along with the associated
147			.I \-x
148			and
149			.I \-y
150			resolution settings.
151			In particular, the color ('c') output data representation
152			together with positive dimensions for
153			.I \-x
154			and
155			.I \-y
156			will produce an uncompressed RADIANCE picture,
157			suitable for manipulation with
158			.I pcomb(1)
159			and related tools.
160	greg	1.1	.PP
161			If the
162			.I \-n
163			option is specified with a value greater than 1, multiple
164	greg	1.2	.I rtrace
165	greg	1.1	processes will be used to accelerate computation on a shared
166			memory machine.
167			Note that there is no benefit to using more processes
168	greg	1.2	than there are local CPUs available to do the work, and the
169			.I rtcontrib
170			process itself may use a considerable amount of CPU time.
171	greg	1.1	.PP
172			Options may be given on the command line and/or read from the
173			environment and/or read from a file.
174			A command argument beginning with a dollar sign ('$') is immediately
175			replaced by the contents of the given environment variable.
176			A command argument beginning with an at sign ('@') is immediately
177			replaced by the contents of the given file.
178	greg	1.2	.SH EXAMPLES
179			To compute the proportional contributions from sources modified
180			by "light1" vs. "light2" on a set of illuminance values:
181	greg	1.1	.IP "" .2i
182	greg	1.2	rtcontrib -I+ @render.opt -o c_%s.dat -m light1 -m light2 scene.oct < test.dat
183			.PP
184			To generate a pair of images corresponding to these two lights'
185			contributions:
186	greg	1.1	.IP "" .2i
187	greg	1.2	vwrays -ff -x 1024 -y 1024 -vf best.vf \|
188			rtcontrib -ffc `vwrays -d -x 1024 -y 1024 -vf best.vf`
189			@render.opt -o c_%s.pic -m light1 -m light2 scene.oct
190			.PP
191			These images may then be recombined using the desired outputs
192			of light1 and light2:
193	greg	1.1	.IP "" .2i
194	greg	1.2	pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
195	greg	1.1	.PP
196	greg	1.2	To compute an array of illuminance contributions according to a Tregenza sky:
197			.IP "" .2i
198			rtcontrib -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
199			@render.opt -f tregenza.cal scene.oct < test.dat
200	greg	1.6	.SH ENVIRONMENT
201			RAYPATH path to search for -f files
202	greg	1.1	.SH AUTHOR
203			Greg Ward
204			.SH "SEE ALSO"
205			cnt(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
206			rcalc(1), rpict(1), rtrace(1), vwrays(1), ximage(1)