man/man1/rtcontrib.1

.\" RCSid "$Id: rtcontrib.1,v 1.2 2005/05/26 18:53:04 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
.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:	1.3
Committed:	Thu May 26 19:19:19 2005 UTC (18 years, 11 months ago) by greg
Branch:	MAIN
Changes since 1.2:	+17 -9 lines
Log Message:	More wording fixes
#	User	Rev	Content
1	greg	1.3	.\" RCSid "$Id: rtcontrib.1,v 1.2 2005/05/26 18:53:04 greg Exp $"
2			.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			.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	greg	1.3	The output of
39			.I rtcontrib
40			has many potential uses.
41			Source contributions can be used as components in linear combination to
42	greg	1.1	reproduce any desired variation, e.g., simulating lighting controls or
43			changing sky conditions via daylight coefficients.
44			More generally,
45			.I rtcontrib
46	greg	1.3	can be used to compute arbitrary input-output relationships in optical
47			systems, such as luminaires, light pipes, and shading devices.
48	greg	1.1	.PP
49	greg	1.2	.I Rtcontrib
50			calls
51			.I rtrace(1)
52			to calculate the contributions for each input ray,
53	greg	1.1	and the output tallies are sent to one or more files according to the
54			.I \-o
55			specification.
56	greg	1.2	If an output specification contains a "%s" format, this will be
57	greg	1.1	replaced by the modifier name.
58			The
59			.I \-b
60			option may be used to further define
61	greg	1.2	a "bin number" within each object if finer resolution is needed, and
62			this will be applied to a "%d" format in the output file
63	greg	1.1	specification if present.
64	greg	1.3	The actual bin number is computed at run time based on ray direction
65			and surface intersection, as described below.
66	greg	1.1	The most recent
67			.I \-b
68			and
69			.I \-o
70	greg	1.2	options to the left of each
71	greg	1.1	.I \-m
72	greg	1.2	setting affect only that modifier.
73			(The ordering of other options is unimportant.)\0
74	greg	1.1	.PP
75	greg	1.2	If a
76			.I \-b
77			expression is defined for a particular modifier,
78			the bin number will be evaluated at run time for each
79			ray contribution from
80			.I rtrace.
81			Specifically, each ray's world intersection point will be assigned to
82			the variables Px, Py, and Pz, and the normalized ray direction
83			will be assigned to Dx, Dy, and Dz.
84			These parameters may be combined with definitions given in
85			.I \-e
86	greg	1.3	arguments and files read using the
87	greg	1.2	.I \-f
88	greg	1.3	option.
89			The computed bin value will be
90	greg	1.2	rounded to the nearest whole number.
91			This mechanism allows the user to define precise regions or directions
92			they wish to accumulate, such as the Tregenza sky discretization,
93			which would be otherwise impossible to specify
94			as a set of RADIANCE primitives.
95	greg	1.3	The rules and predefined functions available for these expressions are
96			described in the
97			.I rcalc(1)
98			man page.
99	greg	1.1	.PP
100			If no
101			.I \-o
102			specification is given, results are written on the standard output in order
103			of modifier (as given on the command line) then bin number.
104	greg	1.2	Concatenated data is also sent to a lone output file (i.e., an initial
105			.I \-o
106			specification without formatting strings).
107	greg	1.1	If a "%s" format appears but no "%d" in the
108			.I \-o
109			specification, then each modifier will have its own output file, with
110			multiple values per record in the case of a non-zero
111			.I \-b
112			definition.
113			If a "%d" format appears but no "%s", then each bin will get its own
114			output file, with modifiers output in order in each record.
115			For text output, each RGB coefficient triple is separated by a tab,
116			with a newline at the end of each ray record.
117			For binary output formats, there is no such delimiter to mark
118			the end of each record.
119			.PP
120	greg	1.2	Input and output format defaults to plain text, where each ray's
121			origin and direction (6 real values) are given on input,
122			and one line is produced per output file per ray.
123			Alternative data representations may be specified by the
124			.I \-f[io]
125			option, which is described in the
126			.I rtrace
127			man page along with the associated
128			.I \-x
129			and
130			.I \-y
131			resolution settings.
132			In particular, the color ('c') output data representation
133			together with positive dimensions for
134			.I \-x
135			and
136			.I \-y
137			will produce an uncompressed RADIANCE picture,
138			suitable for manipulation with
139			.I pcomb(1)
140			and related tools.
141	greg	1.1	.PP
142			If the
143			.I \-n
144			option is specified with a value greater than 1, multiple
145	greg	1.2	.I rtrace
146	greg	1.1	processes will be used to accelerate computation on a shared
147			memory machine.
148			Note that there is no benefit to using more processes
149	greg	1.2	than there are local CPUs available to do the work, and the
150			.I rtcontrib
151			process itself may use a considerable amount of CPU time.
152	greg	1.1	.PP
153			Options may be given on the command line and/or read from the
154			environment and/or read from a file.
155			A command argument beginning with a dollar sign ('$') is immediately
156			replaced by the contents of the given environment variable.
157			A command argument beginning with an at sign ('@') is immediately
158			replaced by the contents of the given file.
159	greg	1.2	.SH EXAMPLES
160			To compute the proportional contributions from sources modified
161			by "light1" vs. "light2" on a set of illuminance values:
162	greg	1.1	.IP "" .2i
163	greg	1.2	rtcontrib -I+ @render.opt -o c_%s.dat -m light1 -m light2 scene.oct < test.dat
164			.PP
165			To generate a pair of images corresponding to these two lights'
166			contributions:
167	greg	1.1	.IP "" .2i
168	greg	1.2	vwrays -ff -x 1024 -y 1024 -vf best.vf \|
169			rtcontrib -ffc `vwrays -d -x 1024 -y 1024 -vf best.vf`
170			@render.opt -o c_%s.pic -m light1 -m light2 scene.oct
171			.PP
172			These images may then be recombined using the desired outputs
173			of light1 and light2:
174	greg	1.1	.IP "" .2i
175	greg	1.2	pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
176	greg	1.1	.PP
177	greg	1.2	To compute an array of illuminance contributions according to a Tregenza sky:
178			.IP "" .2i
179			rtcontrib -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
180			@render.opt -f tregenza.cal scene.oct < test.dat
181	greg	1.1	.SH AUTHOR
182			Greg Ward
183			.SH "SEE ALSO"
184			cnt(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
185			rcalc(1), rpict(1), rtrace(1), vwrays(1), ximage(1)