man/man1/rtcontrib.1

.\" RCSid "$Id: rtcontrib.1,v 1.13 2005/10/06 16:28:59 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 \-fo
|
.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 will not be clobbered, unless the
.I \-fo
option is given.
If instead the
.I \-r
option is specified, data recovery is attempted on existing files.
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:	1.14
Committed:	Tue Oct 11 16:54:26 2005 UTC (18 years, 7 months ago) by greg
Branch:	MAIN
Changes since 1.13:	+8 -3 lines
Log Message:	Added rtcontrib -fo option to override new reluctance to clobber existing files
#	Content
1	.\" RCSid "$Id: rtcontrib.1,v 1.13 2005/10/06 16:28:59 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 \-fo
11	\|
12	.B \-r
13	][
14	.B "\-e expr"
15	][
16	.B "\-f source"
17	][
18	.B "\-o ospec"
19	][
20	.B "\-b binv"
21	][
22	.B "\-bn nbins"
23	]
24	{
25	.B "\-m mod \| \-M file"
26	}
27	..
28	[
29	.B $EVAR
30	]
31	[
32	.B @file
33	]
34	[
35	rtrace options
36	]
37	.B octree
38	.br
39	.B "rtcontrib [ options ] \-defaults"
40	.SH DESCRIPTION
41	.I Rtcontrib
42	computes ray contributions (i.e., color coefficients)
43	for objects whose modifiers are named in one or more
44	.I \-m
45	settings.
46	These modifiers are usually materials associated with
47	light sources or sky domes, and must directly modify some geometric
48	primitives to be considered in the output.
49	A modifier list may also be read from a file using the
50	.I \-M
51	option.
52	The RAYPATH environment variable determines directories to search for
53	this file.
54	(No search takes place if a file name begins with a '.', '/' or '~'
55	character.)\0
56	.PP
57	The output of
58	.I rtcontrib
59	has many potential uses.
60	Source contributions can be used as components in linear combination to
61	reproduce any desired variation, e.g., simulating lighting controls or
62	changing sky conditions via daylight coefficients.
63	More generally,
64	.I rtcontrib
65	can be used to compute arbitrary input-output relationships in optical
66	systems, such as luminaires, light pipes, and shading devices.
67	.PP
68	.I Rtcontrib
69	calls
70	.I rtrace(1)
71	with the -oTW option to calculate the daughter ray
72	contributions for each input ray, and the output tallies
73	are sent to one or more destinations according to the given
74	.I \-o
75	specification.
76	If a destination begins with an exclamation mark ('!'), then
77	a pipe is opened to a command and data is sent to its standard input.
78	Otherwise, the destination is treated as a file.
79	An existing file of the same name will not be clobbered, unless the
80	.I \-fo
81	option is given.
82	If instead the
83	.I \-r
84	option is specified, data recovery is attempted on existing files.
85	If an output specification contains a "%s" format, this will be
86	replaced by the modifier name.
87	The
88	.I \-b
89	option may be used to further define
90	a "bin number" within each object if finer resolution is needed, and
91	this will be applied to a "%d" format in the output file
92	specification if present.
93	The actual bin number is computed at run time based on ray direction
94	and surface intersection, as described below.
95	If the number of bins is known in advance, it should be specified with the
96	.I \-bn
97	option, and this is critical for output files containing multiple values
98	per record.
99	Since bin numbers start from 0, the bin count is always equal to
100	the last bin plus 1.
101	Set the this value to 0 if the bin count is unknown (the default).
102	The most recent
103	.I \-b,
104	.I \-bn
105	and
106	.I \-o
107	options to the left of each
108	.I \-m
109	setting affect only that modifier.
110	(The ordering of other options is unimportant.)\0
111	.PP
112	If a
113	.I \-b
114	expression is defined for a particular modifier,
115	the bin number will be evaluated at run time for each
116	ray contribution from
117	.I rtrace.
118	Specifically, each ray's world intersection point will be assigned to
119	the variables Px, Py, and Pz, and the normalized ray direction
120	will be assigned to Dx, Dy, and Dz.
121	These parameters may be combined with definitions given in
122	.I \-e
123	arguments and files read using the
124	.I \-f
125	option.
126	The computed bin value will be
127	rounded to the nearest whole number.
128	This mechanism allows the user to define precise regions or directions
129	they wish to accumulate, such as the Tregenza sky discretization,
130	which would be otherwise impossible to specify
131	as a set of RADIANCE primitives.
132	The rules and predefined functions available for these expressions are
133	described in the
134	.I rcalc(1)
135	man page.
136	Unlike
137	.I rcalc,
138	.I rtcontrib
139	will search the RADIANCE library directories for each file given in a
140	.I \-f
141	option.
142	.PP
143	If no
144	.I \-o
145	specification is given, results are written on the standard output in order
146	of modifier (as given on the command line) then bin number.
147	Concatenated data is also sent to a single destination (i.e., an initial
148	.I \-o
149	specification without formatting strings).
150	If a "%s" format appears but no "%d" in the
151	.I \-o
152	specification, then each modifier will have its own output file, with
153	multiple values per record in the case of a non-zero
154	.I \-b
155	definition.
156	If a "%d" format appears but no "%s", then each bin will get its own
157	output file, with modifiers output in order in each record.
158	For text output, each RGB coefficient triple is separated by a tab,
159	with a newline at the end of each ray record.
160	For binary output formats, there is no such delimiter to mark
161	the end of each record.
162	.PP
163	Input and output format defaults to plain text, where each ray's
164	origin and direction (6 real values) are given on input,
165	and one line is produced per output file per ray.
166	Alternative data representations may be specified by the
167	.I \-f[io]
168	option, which is described in the
169	.I rtrace
170	man page along with the associated
171	.I \-x
172	and
173	.I \-y
174	resolution settings.
175	In particular, the color ('c') output data representation
176	together with positive dimensions for
177	.I \-x
178	and
179	.I \-y
180	will produce an uncompressed RADIANCE picture,
181	suitable for manipulation with
182	.I pcomb(1)
183	and related tools.
184	.PP
185	If the
186	.I \-n
187	option is specified with a value greater than 1, multiple
188	.I rtrace
189	processes will be used to accelerate computation on a shared
190	memory machine.
191	Note that there is no benefit to using more processes
192	than there are local CPUs available to do the work, and the
193	.I rtcontrib
194	process itself may use a considerable amount of CPU time.
195	.PP
196	Options may be given on the command line and/or read from the
197	environment and/or read from a file.
198	A command argument beginning with a dollar sign ('$') is immediately
199	replaced by the contents of the given environment variable.
200	A command argument beginning with an at sign ('@') is immediately
201	replaced by the contents of the given file.
202	.SH EXAMPLES
203	To compute the proportional contributions from sources modified
204	by "light1" vs. "light2" on a set of illuminance values:
205	.IP "" .2i
206	rtcontrib -I+ @render.opt -o c_%s.dat -m light1 -m light2 scene.oct < test.dat
207	.PP
208	To generate a pair of images corresponding to these two lights'
209	contributions:
210	.IP "" .2i
211	vwrays -ff -x 1024 -y 1024 -vf best.vf \|
212	rtcontrib -ffc `vwrays -d -x 1024 -y 1024 -vf best.vf`
213	@render.opt -o c_%s.pic -m light1 -m light2 scene.oct
214	.PP
215	These images may then be recombined using the desired outputs
216	of light1 and light2:
217	.IP "" .2i
218	pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
219	.PP
220	To compute an array of illuminance contributions according to a Tregenza sky:
221	.IP "" .2i
222	rtcontrib -I+ -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
223	@render.opt -f tregenza.cal scene.oct < test.dat
224	.SH ENVIRONMENT
225	RAYPATH path to search for -f and -M files
226	.SH AUTHOR
227	Greg Ward
228	.SH "SEE ALSO"
229	cnt(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
230	rcalc(1), rpict(1), rtrace(1), vwrays(1), ximage(1)