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Revision 1.2 by greg, Thu May 26 18:53:04 2005 UTC vs.
Revision 1.12 by greg, Thu Oct 6 05:49:44 2005 UTC

# Line 1 | Line 1
1   .\" RCSid "$Id$"
2 < .TH RPIECE 1 5/25/05 RADIANCE
2 > .TH RTCONTRIB 1 5/25/05 RADIANCE
3   .SH NAME
4 < rtcontrib - compute contributions in a RADIANCE scene
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 fspec"
16 > .B "\-o ospec"
17   ][
18   .B "\-b binv"
19 + ][
20 + .B "\-bn nbins"
21   ]
22 < .B "\-m mod .."
22 > {
23 > .B "\-m mod | \-M file"
24 > }
25 > ..
26   [
27   .B $EVAR
28   ]
# Line 26 | Line 33 | rtcontrib - compute contributions in a RADIANCE scene
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)
# Line 35 | Line 44 | 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 < The computed contributions can then be used in linear combination to
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 < may be used to compute input-output relationships in optical
64 < systems, such as light pipes and shading devices.
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 < to calculate the contributions for each input ray,
70 < and the output tallies are sent to one or more files according to the
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
# Line 58 | Line 85 | 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.)\0
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, especially for output files containing multiple bins.
93 > Set this to 0 if the number of bins is unknown (the default).
94   The most recent
95 < .I \-b
95 > .I \-b,
96 > .I \-bn
97   and
98   .I \-o
99   options to the left of each
# Line 80 | Line 112 | the variables Px, Py, and Pz, and the normalized ray d
112   will be assigned to Dx, Dy, and Dz.
113   These parameters may be combined with definitions given in
114   .I \-e
115 < options and files read in
115 > arguments and files read using the
116   .I \-f
117 < options, to compute the bin, which will be
117 > option.
118 > The computed bin value will be
119   rounded to the nearest whole number.
120   This mechanism allows the user to define precise regions or directions
121   they wish to accumulate, such as the Tregenza sky discretization,
122   which would be otherwise impossible to specify
123   as a set of RADIANCE primitives.
124 + The rules and predefined functions available for these expressions are
125 + described in the
126 + .I rcalc(1)
127 + man page.
128 + Unlike
129 + .I rcalc,
130 + .I rtcontrib
131 + will search the RADIANCE library directories for each file given in a
132 + .I \-f
133 + option.
134   .PP
135   If no
136   .I \-o
137   specification is given, results are written on the standard output in order
138   of modifier (as given on the command line) then bin number.
139 < Concatenated data is also sent to a lone output file (i.e., an initial
139 > Concatenated data is also sent to a single destination (i.e., an initial
140   .I \-o
141   specification without formatting strings).
142   If a "%s" format appears but no "%d" in the
# Line 168 | Line 211 | pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.p
211   .PP
212   To compute an array of illuminance contributions according to a Tregenza sky:
213   .IP "" .2i
214 < rtcontrib -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
214 > rtcontrib -I+ -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
215   @render.opt -f tregenza.cal scene.oct < test.dat
216 + .SH ENVIRONMENT
217 + RAYPATH         path to search for -f and -M files
218   .SH AUTHOR
219   Greg Ward
220   .SH "SEE ALSO"

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