man/man1/rtcontrib.1

.\" RCSid "$Id: rtcontrib.1,v 1.1 2005/05/26 06:55:22 greg Exp $"
.TH RPIECE 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 computed contributions can then be used in linear combination to
reproduce any desired variation, e.g., simulating lighting controls or
changing sky conditions via daylight coefficients.
More generally,
.I rtcontrib
may be used to compute input-output relationships in optical
systems, such as 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.)\0
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
options and files read in
.I \-f
options, to compute the bin, which 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.
.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:	1.2
Committed:	Thu May 26 18:53:04 2005 UTC (19 years ago) by greg
Branch:	MAIN
Changes since 1.1:	+82 -126 lines
Log Message:	Finished basic man page
#	Content
1	.\" RCSid "$Id: rtcontrib.1,v 1.1 2005/05/26 06:55:22 greg Exp $"
2	.TH RPIECE 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 computed contributions can then be used in linear combination to
39	reproduce any desired variation, e.g., simulating lighting controls or
40	changing sky conditions via daylight coefficients.
41	More generally,
42	.I rtcontrib
43	may be used to compute input-output relationships in optical
44	systems, such as light pipes and shading devices.
45	.PP
46	.I Rtcontrib
47	calls
48	.I rtrace(1)
49	to calculate the contributions for each input ray,
50	and the output tallies are sent to one or more files according to the
51	.I \-o
52	specification.
53	If an output specification contains a "%s" format, this will be
54	replaced by the modifier name.
55	The
56	.I \-b
57	option may be used to further define
58	a "bin number" within each object if finer resolution is needed, and
59	this will be applied to a "%d" format in the output file
60	specification if present.
61	(The actual bin number is computed at run time based on ray direction
62	and surface intersection, as described below.)\0
63	The most recent
64	.I \-b
65	and
66	.I \-o
67	options to the left of each
68	.I \-m
69	setting affect only that modifier.
70	(The ordering of other options is unimportant.)\0
71	.PP
72	If a
73	.I \-b
74	expression is defined for a particular modifier,
75	the bin number will be evaluated at run time for each
76	ray contribution from
77	.I rtrace.
78	Specifically, each ray's world intersection point will be assigned to
79	the variables Px, Py, and Pz, and the normalized ray direction
80	will be assigned to Dx, Dy, and Dz.
81	These parameters may be combined with definitions given in
82	.I \-e
83	options and files read in
84	.I \-f
85	options, to compute the bin, which will be
86	rounded to the nearest whole number.
87	This mechanism allows the user to define precise regions or directions
88	they wish to accumulate, such as the Tregenza sky discretization,
89	which would be otherwise impossible to specify
90	as a set of RADIANCE primitives.
91	.PP
92	If no
93	.I \-o
94	specification is given, results are written on the standard output in order
95	of modifier (as given on the command line) then bin number.
96	Concatenated data is also sent to a lone output file (i.e., an initial
97	.I \-o
98	specification without formatting strings).
99	If a "%s" format appears but no "%d" in the
100	.I \-o
101	specification, then each modifier will have its own output file, with
102	multiple values per record in the case of a non-zero
103	.I \-b
104	definition.
105	If a "%d" format appears but no "%s", then each bin will get its own
106	output file, with modifiers output in order in each record.
107	For text output, each RGB coefficient triple is separated by a tab,
108	with a newline at the end of each ray record.
109	For binary output formats, there is no such delimiter to mark
110	the end of each record.
111	.PP
112	Input and output format defaults to plain text, where each ray's
113	origin and direction (6 real values) are given on input,
114	and one line is produced per output file per ray.
115	Alternative data representations may be specified by the
116	.I \-f[io]
117	option, which is described in the
118	.I rtrace
119	man page along with the associated
120	.I \-x
121	and
122	.I \-y
123	resolution settings.
124	In particular, the color ('c') output data representation
125	together with positive dimensions for
126	.I \-x
127	and
128	.I \-y
129	will produce an uncompressed RADIANCE picture,
130	suitable for manipulation with
131	.I pcomb(1)
132	and related tools.
133	.PP
134	If the
135	.I \-n
136	option is specified with a value greater than 1, multiple
137	.I rtrace
138	processes will be used to accelerate computation on a shared
139	memory machine.
140	Note that there is no benefit to using more processes
141	than there are local CPUs available to do the work, and the
142	.I rtcontrib
143	process itself may use a considerable amount of CPU time.
144	.PP
145	Options may be given on the command line and/or read from the
146	environment and/or read from a file.
147	A command argument beginning with a dollar sign ('$') is immediately
148	replaced by the contents of the given environment variable.
149	A command argument beginning with an at sign ('@') is immediately
150	replaced by the contents of the given file.
151	.SH EXAMPLES
152	To compute the proportional contributions from sources modified
153	by "light1" vs. "light2" on a set of illuminance values:
154	.IP "" .2i
155	rtcontrib -I+ @render.opt -o c_%s.dat -m light1 -m light2 scene.oct < test.dat
156	.PP
157	To generate a pair of images corresponding to these two lights'
158	contributions:
159	.IP "" .2i
160	vwrays -ff -x 1024 -y 1024 -vf best.vf \|
161	rtcontrib -ffc `vwrays -d -x 1024 -y 1024 -vf best.vf`
162	@render.opt -o c_%s.pic -m light1 -m light2 scene.oct
163	.PP
164	These images may then be recombined using the desired outputs
165	of light1 and light2:
166	.IP "" .2i
167	pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
168	.PP
169	To compute an array of illuminance contributions according to a Tregenza sky:
170	.IP "" .2i
171	rtcontrib -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
172	@render.opt -f tregenza.cal scene.oct < test.dat
173	.SH AUTHOR
174	Greg Ward
175	.SH "SEE ALSO"
176	cnt(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
177	rcalc(1), rpict(1), rtrace(1), vwrays(1), ximage(1)