man/man1/rtcontrib.1

.\" RCSid "$Id: rtcontrib.1,v 1.1 2005/05/26 06:55:22 greg Exp $"
.TH RPIECE 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
.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 computed contributions can then be used in linear combination to
reproduce any desired variation, e.g., simulating lighting controls or
changing sky conditions via daylight coefficients.
More generally,
.I rtcontrib
may be used to compute input-output relationships in optical
systems, such as 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.)\0
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
options and files read in
.I \-f
options, to compute the bin, which 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.
.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:	1.2
Committed:	Thu May 26 18:53:04 2005 UTC (18 years, 11 months ago) by greg
Branch:	MAIN
Changes since 1.1:	+82 -126 lines
Log Message:	Finished basic man page
#	User	Rev	Content
1	greg	1.2	.\" RCSid "$Id: rtcontrib.1,v 1.1 2005/05/26 06:55:22 greg Exp $"
2	greg	1.1	.TH RPIECE 1 5/25/05 RADIANCE
3			.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			.SH DESCRIPTION
30			.I Rtcontrib
31			computes ray contributions (i.e., color coefficients)
32			for objects whose modifiers are named in one or more
33			.I \-m
34			settings.
35	greg	1.2	These modifiers are usually materials associated with
36			light sources or sky domes, and must directly modify some geometric
37			primitives to be considered in the output.
38			The computed contributions can then be used in linear combination to
39	greg	1.1	reproduce any desired variation, e.g., simulating lighting controls or
40			changing sky conditions via daylight coefficients.
41			More generally,
42			.I rtcontrib
43	greg	1.2	may be used to compute input-output relationships in optical
44	greg	1.1	systems, such as light pipes and shading devices.
45			.PP
46	greg	1.2	.I Rtcontrib
47			calls
48			.I rtrace(1)
49			to calculate the contributions for each input ray,
50	greg	1.1	and the output tallies are sent to one or more files according to the
51			.I \-o
52			specification.
53	greg	1.2	If an output specification contains a "%s" format, this will be
54	greg	1.1	replaced by the modifier name.
55			The
56			.I \-b
57			option may be used to further define
58	greg	1.2	a "bin number" within each object if finer resolution is needed, and
59			this will be applied to a "%d" format in the output file
60	greg	1.1	specification if present.
61			(The actual bin number is computed at run time based on ray direction
62			and surface intersection, as described below.)\0
63			The most recent
64			.I \-b
65			and
66			.I \-o
67	greg	1.2	options to the left of each
68	greg	1.1	.I \-m
69	greg	1.2	setting affect only that modifier.
70			(The ordering of other options is unimportant.)\0
71	greg	1.1	.PP
72	greg	1.2	If a
73			.I \-b
74			expression is defined for a particular modifier,
75			the bin number will be evaluated at run time for each
76			ray contribution from
77			.I rtrace.
78			Specifically, each ray's world intersection point will be assigned to
79			the variables Px, Py, and Pz, and the normalized ray direction
80			will be assigned to Dx, Dy, and Dz.
81			These parameters may be combined with definitions given in
82			.I \-e
83			options and files read in
84			.I \-f
85			options, to compute the bin, which will be
86			rounded to the nearest whole number.
87			This mechanism allows the user to define precise regions or directions
88			they wish to accumulate, such as the Tregenza sky discretization,
89			which would be otherwise impossible to specify
90			as a set of RADIANCE primitives.
91	greg	1.1	.PP
92			If no
93			.I \-o
94			specification is given, results are written on the standard output in order
95			of modifier (as given on the command line) then bin number.
96	greg	1.2	Concatenated data is also sent to a lone output file (i.e., an initial
97			.I \-o
98			specification without formatting strings).
99	greg	1.1	If a "%s" format appears but no "%d" in the
100			.I \-o
101			specification, then each modifier will have its own output file, with
102			multiple values per record in the case of a non-zero
103			.I \-b
104			definition.
105			If a "%d" format appears but no "%s", then each bin will get its own
106			output file, with modifiers output in order in each record.
107			For text output, each RGB coefficient triple is separated by a tab,
108			with a newline at the end of each ray record.
109			For binary output formats, there is no such delimiter to mark
110			the end of each record.
111			.PP
112	greg	1.2	Input and output format defaults to plain text, where each ray's
113			origin and direction (6 real values) are given on input,
114			and one line is produced per output file per ray.
115			Alternative data representations may be specified by the
116			.I \-f[io]
117			option, which is described in the
118			.I rtrace
119			man page along with the associated
120			.I \-x
121			and
122			.I \-y
123			resolution settings.
124			In particular, the color ('c') output data representation
125			together with positive dimensions for
126			.I \-x
127			and
128			.I \-y
129			will produce an uncompressed RADIANCE picture,
130			suitable for manipulation with
131			.I pcomb(1)
132			and related tools.
133	greg	1.1	.PP
134			If the
135			.I \-n
136			option is specified with a value greater than 1, multiple
137	greg	1.2	.I rtrace
138	greg	1.1	processes will be used to accelerate computation on a shared
139			memory machine.
140			Note that there is no benefit to using more processes
141	greg	1.2	than there are local CPUs available to do the work, and the
142			.I rtcontrib
143			process itself may use a considerable amount of CPU time.
144	greg	1.1	.PP
145			Options may be given on the command line and/or read from the
146			environment and/or read from a file.
147			A command argument beginning with a dollar sign ('$') is immediately
148			replaced by the contents of the given environment variable.
149			A command argument beginning with an at sign ('@') is immediately
150			replaced by the contents of the given file.
151	greg	1.2	.SH EXAMPLES
152			To compute the proportional contributions from sources modified
153			by "light1" vs. "light2" on a set of illuminance values:
154	greg	1.1	.IP "" .2i
155	greg	1.2	rtcontrib -I+ @render.opt -o c_%s.dat -m light1 -m light2 scene.oct < test.dat
156			.PP
157			To generate a pair of images corresponding to these two lights'
158			contributions:
159	greg	1.1	.IP "" .2i
160	greg	1.2	vwrays -ff -x 1024 -y 1024 -vf best.vf \|
161			rtcontrib -ffc `vwrays -d -x 1024 -y 1024 -vf best.vf`
162			@render.opt -o c_%s.pic -m light1 -m light2 scene.oct
163			.PP
164			These images may then be recombined using the desired outputs
165			of light1 and light2:
166	greg	1.1	.IP "" .2i
167	greg	1.2	pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
168	greg	1.1	.PP
169	greg	1.2	To compute an array of illuminance contributions according to a Tregenza sky:
170			.IP "" .2i
171			rtcontrib -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
172			@render.opt -f tregenza.cal scene.oct < test.dat
173	greg	1.1	.SH AUTHOR
174			Greg Ward
175			.SH "SEE ALSO"
176			cnt(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
177			rcalc(1), rpict(1), rtrace(1), vwrays(1), ximage(1)