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
#	Content
1	.\" RCSid "$Id: rtcontrib.1,v 1.3 2005/05/26 19:19:19 greg Exp $"
2	.TH RTCONTRIB 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	.B "\-m mod .."
19	[
20	.B $EVAR
21	]
22	[
23	.B @file
24	]
25	[
26	rtrace options
27	]
28	.B octree
29	.br
30	.B "rtcontrib [ options ] \-defaults"
31	.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	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	The output of
41	.I rtcontrib
42	has many potential uses.
43	Source contributions can be used as components in linear combination to
44	reproduce any desired variation, e.g., simulating lighting controls or
45	changing sky conditions via daylight coefficients.
46	More generally,
47	.I rtcontrib
48	can be used to compute arbitrary input-output relationships in optical
49	systems, such as luminaires, light pipes, and shading devices.
50	.PP
51	.I Rtcontrib
52	calls
53	.I rtrace(1)
54	to calculate the contributions for each input ray,
55	and the output tallies are sent to one or more files according to the
56	.I \-o
57	specification.
58	If an output specification contains a "%s" format, this will be
59	replaced by the modifier name.
60	The
61	.I \-b
62	option may be used to further define
63	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	specification if present.
66	The actual bin number is computed at run time based on ray direction
67	and surface intersection, as described below.
68	The most recent
69	.I \-b
70	and
71	.I \-o
72	options to the left of each
73	.I \-m
74	setting affect only that modifier.
75	(The ordering of other options is unimportant.)\0
76	.PP
77	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	arguments and files read using the
89	.I \-f
90	option.
91	The computed bin value will be
92	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	The rules and predefined functions available for these expressions are
98	described in the
99	.I rcalc(1)
100	man page.
101	.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	Concatenated data is also sent to a lone output file (i.e., an initial
107	.I \-o
108	specification without formatting strings).
109	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	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	.PP
144	If the
145	.I \-n
146	option is specified with a value greater than 1, multiple
147	.I rtrace
148	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	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	.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	.SH EXAMPLES
162	To compute the proportional contributions from sources modified
163	by "light1" vs. "light2" on a set of illuminance values:
164	.IP "" .2i
165	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	.IP "" .2i
170	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	.IP "" .2i
177	pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
178	.PP
179	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	.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)