man/man1/rtcontrib.1

.\" RCSid "$Id: rtcontrib.1,v 1.3 2005/05/26 19:19:19 greg Exp $"
.TH RTCONTRIB 1 5/25/05 RADIANCE
.SH NAME
rtcontrib - compute contributions in a RADIANCE scene
.SH SYNOPSIS
.B rtcontrib
[
.B "\-n nprocs"
][
.B "\-e expr"
][
.B "\-f source"
][
.B "\-o fspec"
][
.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)
to calculate the contributions for each input ray,
and the output tallies are sent to one or more files according to the
.I \-o
specification.
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.
.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 lone output file (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 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:	1.4
Committed:	Thu May 26 21:03:22 2005 UTC (19 years ago) by greg
Branch:	MAIN
Changes since 1.3:	+3 -1 lines
Log Message:	Added -defaults invocation to synopsis
#	User	Rev	Content
1	greg	1.4	.\" RCSid "$Id: rtcontrib.1,v 1.3 2005/05/26 19:19:19 greg Exp $"
2	greg	1.3	.TH RTCONTRIB 1 5/25/05 RADIANCE
3	greg	1.1	.SH NAME
4			rtcontrib - compute contributions in a RADIANCE scene
5			.SH SYNOPSIS
6			.B rtcontrib
7			[
8			.B "\-n nprocs"
9			][
10			.B "\-e expr"
11			][
12			.B "\-f source"
13			][
14			.B "\-o fspec"
15			][
16			.B "\-b binv"
17			]
18	greg	1.2	.B "\-m mod .."
19	greg	1.1	[
20			.B $EVAR
21			]
22			[
23			.B @file
24			]
25			[
26			rtrace options
27			]
28			.B octree
29	greg	1.4	.br
30			.B "rtcontrib [ options ] \-defaults"
31	greg	1.1	.SH DESCRIPTION
32			.I Rtcontrib
33			computes ray contributions (i.e., color coefficients)
34			for objects whose modifiers are named in one or more
35			.I \-m
36			settings.
37	greg	1.2	These modifiers are usually materials associated with
38			light sources or sky domes, and must directly modify some geometric
39			primitives to be considered in the output.
40	greg	1.3	The output of
41			.I rtcontrib
42			has many potential uses.
43			Source contributions can be used as components in linear combination to
44	greg	1.1	reproduce any desired variation, e.g., simulating lighting controls or
45			changing sky conditions via daylight coefficients.
46			More generally,
47			.I rtcontrib
48	greg	1.3	can be used to compute arbitrary input-output relationships in optical
49			systems, such as luminaires, light pipes, and shading devices.
50	greg	1.1	.PP
51	greg	1.2	.I Rtcontrib
52			calls
53			.I rtrace(1)
54			to calculate the contributions for each input ray,
55	greg	1.1	and the output tallies are sent to one or more files according to the
56			.I \-o
57			specification.
58	greg	1.2	If an output specification contains a "%s" format, this will be
59	greg	1.1	replaced by the modifier name.
60			The
61			.I \-b
62			option may be used to further define
63	greg	1.2	a "bin number" within each object if finer resolution is needed, and
64			this will be applied to a "%d" format in the output file
65	greg	1.1	specification if present.
66	greg	1.3	The actual bin number is computed at run time based on ray direction
67			and surface intersection, as described below.
68	greg	1.1	The most recent
69			.I \-b
70			and
71			.I \-o
72	greg	1.2	options to the left of each
73	greg	1.1	.I \-m
74	greg	1.2	setting affect only that modifier.
75			(The ordering of other options is unimportant.)\0
76	greg	1.1	.PP
77	greg	1.2	If a
78			.I \-b
79			expression is defined for a particular modifier,
80			the bin number will be evaluated at run time for each
81			ray contribution from
82			.I rtrace.
83			Specifically, each ray's world intersection point will be assigned to
84			the variables Px, Py, and Pz, and the normalized ray direction
85			will be assigned to Dx, Dy, and Dz.
86			These parameters may be combined with definitions given in
87			.I \-e
88	greg	1.3	arguments and files read using the
89	greg	1.2	.I \-f
90	greg	1.3	option.
91			The computed bin value will be
92	greg	1.2	rounded to the nearest whole number.
93			This mechanism allows the user to define precise regions or directions
94			they wish to accumulate, such as the Tregenza sky discretization,
95			which would be otherwise impossible to specify
96			as a set of RADIANCE primitives.
97	greg	1.3	The rules and predefined functions available for these expressions are
98			described in the
99			.I rcalc(1)
100			man page.
101	greg	1.1	.PP
102			If no
103			.I \-o
104			specification is given, results are written on the standard output in order
105			of modifier (as given on the command line) then bin number.
106	greg	1.2	Concatenated data is also sent to a lone output file (i.e., an initial
107			.I \-o
108			specification without formatting strings).
109	greg	1.1	If a "%s" format appears but no "%d" in the
110			.I \-o
111			specification, then each modifier will have its own output file, with
112			multiple values per record in the case of a non-zero
113			.I \-b
114			definition.
115			If a "%d" format appears but no "%s", then each bin will get its own
116			output file, with modifiers output in order in each record.
117			For text output, each RGB coefficient triple is separated by a tab,
118			with a newline at the end of each ray record.
119			For binary output formats, there is no such delimiter to mark
120			the end of each record.
121			.PP
122	greg	1.2	Input and output format defaults to plain text, where each ray's
123			origin and direction (6 real values) are given on input,
124			and one line is produced per output file per ray.
125			Alternative data representations may be specified by the
126			.I \-f[io]
127			option, which is described in the
128			.I rtrace
129			man page along with the associated
130			.I \-x
131			and
132			.I \-y
133			resolution settings.
134			In particular, the color ('c') output data representation
135			together with positive dimensions for
136			.I \-x
137			and
138			.I \-y
139			will produce an uncompressed RADIANCE picture,
140			suitable for manipulation with
141			.I pcomb(1)
142			and related tools.
143	greg	1.1	.PP
144			If the
145			.I \-n
146			option is specified with a value greater than 1, multiple
147	greg	1.2	.I rtrace
148	greg	1.1	processes will be used to accelerate computation on a shared
149			memory machine.
150			Note that there is no benefit to using more processes
151	greg	1.2	than there are local CPUs available to do the work, and the
152			.I rtcontrib
153			process itself may use a considerable amount of CPU time.
154	greg	1.1	.PP
155			Options may be given on the command line and/or read from the
156			environment and/or read from a file.
157			A command argument beginning with a dollar sign ('$') is immediately
158			replaced by the contents of the given environment variable.
159			A command argument beginning with an at sign ('@') is immediately
160			replaced by the contents of the given file.
161	greg	1.2	.SH EXAMPLES
162			To compute the proportional contributions from sources modified
163			by "light1" vs. "light2" on a set of illuminance values:
164	greg	1.1	.IP "" .2i
165	greg	1.2	rtcontrib -I+ @render.opt -o c_%s.dat -m light1 -m light2 scene.oct < test.dat
166			.PP
167			To generate a pair of images corresponding to these two lights'
168			contributions:
169	greg	1.1	.IP "" .2i
170	greg	1.2	vwrays -ff -x 1024 -y 1024 -vf best.vf \|
171			rtcontrib -ffc `vwrays -d -x 1024 -y 1024 -vf best.vf`
172			@render.opt -o c_%s.pic -m light1 -m light2 scene.oct
173			.PP
174			These images may then be recombined using the desired outputs
175			of light1 and light2:
176	greg	1.1	.IP "" .2i
177	greg	1.2	pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
178	greg	1.1	.PP
179	greg	1.2	To compute an array of illuminance contributions according to a Tregenza sky:
180			.IP "" .2i
181			rtcontrib -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
182			@render.opt -f tregenza.cal scene.oct < test.dat
183	greg	1.1	.SH AUTHOR
184			Greg Ward
185			.SH "SEE ALSO"
186			cnt(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
187			rcalc(1), rpict(1), rtrace(1), vwrays(1), ximage(1)