man/man1/rtcontrib.1

.\" RCSid "$Id: rtcontrib.1,v 1.12 2005/10/06 05:49:44 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 "\-bn nbins"
]
{
.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.
The RAYPATH environment variable determines directories to search for
this file.
(No search takes place if a file name begins with a '.', '/' or '~'
character.)\0
.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.
If the number of bins is known in advance, it should be specified with the
.I \-bn
option, and this is critical for output files containing multiple values
per record.
Since bin numbers start from 0, the bin count is always equal to
the last bin plus 1.
Set the this value to 0 if the bin count is unknown (the default).
The most recent
.I \-b,
.I \-bn
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.
.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 -I+ -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 and -M 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:	1.13
Committed:	Thu Oct 6 16:28:59 2005 UTC (18 years, 8 months ago) by greg
Branch:	MAIN
Changes since 1.12:	+6 -3 lines
Log Message:	Fixes in new rtcontrib -bn option
#	Content
1	.\" RCSid "$Id: rtcontrib.1,v 1.12 2005/10/06 05:49:44 greg Exp $"
2	.TH RTCONTRIB 1 5/25/05 RADIANCE
3	.SH NAME
4	rtcontrib - compute contribution coefficients in a RADIANCE scene
5	.SH SYNOPSIS
6	.B rtcontrib
7	[
8	.B "\-n nprocs"
9	][
10	.B \-r
11	][
12	.B "\-e expr"
13	][
14	.B "\-f source"
15	][
16	.B "\-o ospec"
17	][
18	.B "\-b binv"
19	][
20	.B "\-bn nbins"
21	]
22	{
23	.B "\-m mod \| \-M file"
24	}
25	..
26	[
27	.B $EVAR
28	]
29	[
30	.B @file
31	]
32	[
33	rtrace options
34	]
35	.B octree
36	.br
37	.B "rtcontrib [ options ] \-defaults"
38	.SH DESCRIPTION
39	.I Rtcontrib
40	computes ray contributions (i.e., color coefficients)
41	for objects whose modifiers are named in one or more
42	.I \-m
43	settings.
44	These modifiers are usually materials associated with
45	light sources or sky domes, and must directly modify some geometric
46	primitives to be considered in the output.
47	A modifier list may also be read from a file using the
48	.I \-M
49	option.
50	The RAYPATH environment variable determines directories to search for
51	this file.
52	(No search takes place if a file name begins with a '.', '/' or '~'
53	character.)\0
54	.PP
55	The output of
56	.I rtcontrib
57	has many potential uses.
58	Source contributions can be used as components in linear combination to
59	reproduce any desired variation, e.g., simulating lighting controls or
60	changing sky conditions via daylight coefficients.
61	More generally,
62	.I rtcontrib
63	can be used to compute arbitrary input-output relationships in optical
64	systems, such as luminaires, light pipes, and shading devices.
65	.PP
66	.I Rtcontrib
67	calls
68	.I rtrace(1)
69	with the -oTW option to calculate the daughter ray
70	contributions for each input ray, and the output tallies
71	are sent to one or more destinations according to the given
72	.I \-o
73	specification.
74	If a destination begins with an exclamation mark ('!'), then
75	a pipe is opened to a command and data is sent to its standard input.
76	Otherwise, the destination is treated as a file.
77	An existing file of the same name is clobbered, unless the
78	.I \-r
79	option is specified, in which case data recovery is attempted.
80	If an output specification contains a "%s" format, this will be
81	replaced by the modifier name.
82	The
83	.I \-b
84	option may be used to further define
85	a "bin number" within each object if finer resolution is needed, and
86	this will be applied to a "%d" format in the output file
87	specification if present.
88	The actual bin number is computed at run time based on ray direction
89	and surface intersection, as described below.
90	If the number of bins is known in advance, it should be specified with the
91	.I \-bn
92	option, and this is critical for output files containing multiple values
93	per record.
94	Since bin numbers start from 0, the bin count is always equal to
95	the last bin plus 1.
96	Set the this value to 0 if the bin count is unknown (the default).
97	The most recent
98	.I \-b,
99	.I \-bn
100	and
101	.I \-o
102	options to the left of each
103	.I \-m
104	setting affect only that modifier.
105	(The ordering of other options is unimportant.)\0
106	.PP
107	If a
108	.I \-b
109	expression is defined for a particular modifier,
110	the bin number will be evaluated at run time for each
111	ray contribution from
112	.I rtrace.
113	Specifically, each ray's world intersection point will be assigned to
114	the variables Px, Py, and Pz, and the normalized ray direction
115	will be assigned to Dx, Dy, and Dz.
116	These parameters may be combined with definitions given in
117	.I \-e
118	arguments and files read using the
119	.I \-f
120	option.
121	The computed bin value will be
122	rounded to the nearest whole number.
123	This mechanism allows the user to define precise regions or directions
124	they wish to accumulate, such as the Tregenza sky discretization,
125	which would be otherwise impossible to specify
126	as a set of RADIANCE primitives.
127	The rules and predefined functions available for these expressions are
128	described in the
129	.I rcalc(1)
130	man page.
131	Unlike
132	.I rcalc,
133	.I rtcontrib
134	will search the RADIANCE library directories for each file given in a
135	.I \-f
136	option.
137	.PP
138	If no
139	.I \-o
140	specification is given, results are written on the standard output in order
141	of modifier (as given on the command line) then bin number.
142	Concatenated data is also sent to a single destination (i.e., an initial
143	.I \-o
144	specification without formatting strings).
145	If a "%s" format appears but no "%d" in the
146	.I \-o
147	specification, then each modifier will have its own output file, with
148	multiple values per record in the case of a non-zero
149	.I \-b
150	definition.
151	If a "%d" format appears but no "%s", then each bin will get its own
152	output file, with modifiers output in order in each record.
153	For text output, each RGB coefficient triple is separated by a tab,
154	with a newline at the end of each ray record.
155	For binary output formats, there is no such delimiter to mark
156	the end of each record.
157	.PP
158	Input and output format defaults to plain text, where each ray's
159	origin and direction (6 real values) are given on input,
160	and one line is produced per output file per ray.
161	Alternative data representations may be specified by the
162	.I \-f[io]
163	option, which is described in the
164	.I rtrace
165	man page along with the associated
166	.I \-x
167	and
168	.I \-y
169	resolution settings.
170	In particular, the color ('c') output data representation
171	together with positive dimensions for
172	.I \-x
173	and
174	.I \-y
175	will produce an uncompressed RADIANCE picture,
176	suitable for manipulation with
177	.I pcomb(1)
178	and related tools.
179	.PP
180	If the
181	.I \-n
182	option is specified with a value greater than 1, multiple
183	.I rtrace
184	processes will be used to accelerate computation on a shared
185	memory machine.
186	Note that there is no benefit to using more processes
187	than there are local CPUs available to do the work, and the
188	.I rtcontrib
189	process itself may use a considerable amount of CPU time.
190	.PP
191	Options may be given on the command line and/or read from the
192	environment and/or read from a file.
193	A command argument beginning with a dollar sign ('$') is immediately
194	replaced by the contents of the given environment variable.
195	A command argument beginning with an at sign ('@') is immediately
196	replaced by the contents of the given file.
197	.SH EXAMPLES
198	To compute the proportional contributions from sources modified
199	by "light1" vs. "light2" on a set of illuminance values:
200	.IP "" .2i
201	rtcontrib -I+ @render.opt -o c_%s.dat -m light1 -m light2 scene.oct < test.dat
202	.PP
203	To generate a pair of images corresponding to these two lights'
204	contributions:
205	.IP "" .2i
206	vwrays -ff -x 1024 -y 1024 -vf best.vf \|
207	rtcontrib -ffc `vwrays -d -x 1024 -y 1024 -vf best.vf`
208	@render.opt -o c_%s.pic -m light1 -m light2 scene.oct
209	.PP
210	These images may then be recombined using the desired outputs
211	of light1 and light2:
212	.IP "" .2i
213	pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
214	.PP
215	To compute an array of illuminance contributions according to a Tregenza sky:
216	.IP "" .2i
217	rtcontrib -I+ -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
218	@render.opt -f tregenza.cal scene.oct < test.dat
219	.SH ENVIRONMENT
220	RAYPATH path to search for -f and -M files
221	.SH AUTHOR
222	Greg Ward
223	.SH "SEE ALSO"
224	cnt(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
225	rcalc(1), rpict(1), rtrace(1), vwrays(1), ximage(1)