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 (19 years ago) by greg
Branch:	MAIN
Changes since 1.2:	+17 -9 lines
Log Message:	More wording fixes
#	Content
1	.\" RCSid "$Id: rtcontrib.1,v 1.2 2005/05/26 18:53:04 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	.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	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 output of
39	.I rtcontrib
40	has many potential uses.
41	Source contributions can be used as components in linear combination to
42	reproduce any desired variation, e.g., simulating lighting controls or
43	changing sky conditions via daylight coefficients.
44	More generally,
45	.I rtcontrib
46	can be used to compute arbitrary input-output relationships in optical
47	systems, such as luminaires, light pipes, and shading devices.
48	.PP
49	.I Rtcontrib
50	calls
51	.I rtrace(1)
52	to calculate the contributions for each input ray,
53	and the output tallies are sent to one or more files according to the
54	.I \-o
55	specification.
56	If an output specification contains a "%s" format, this will be
57	replaced by the modifier name.
58	The
59	.I \-b
60	option may be used to further define
61	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	specification if present.
64	The actual bin number is computed at run time based on ray direction
65	and surface intersection, as described below.
66	The most recent
67	.I \-b
68	and
69	.I \-o
70	options to the left of each
71	.I \-m
72	setting affect only that modifier.
73	(The ordering of other options is unimportant.)\0
74	.PP
75	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	arguments and files read using the
87	.I \-f
88	option.
89	The computed bin value will be
90	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	The rules and predefined functions available for these expressions are
96	described in the
97	.I rcalc(1)
98	man page.
99	.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	Concatenated data is also sent to a lone output file (i.e., an initial
105	.I \-o
106	specification without formatting strings).
107	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	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	.PP
142	If the
143	.I \-n
144	option is specified with a value greater than 1, multiple
145	.I rtrace
146	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	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	.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	.SH EXAMPLES
160	To compute the proportional contributions from sources modified
161	by "light1" vs. "light2" on a set of illuminance values:
162	.IP "" .2i
163	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	.IP "" .2i
168	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	.IP "" .2i
175	pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
176	.PP
177	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	.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)