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Revision 1.2 by greg, Thu May 26 18:53:04 2005 UTC vs.
Revision 1.13 by greg, Thu Oct 6 16:28:59 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, and this is critical for output files containing multiple values
93 > per record.
94 > Since bin numbers start from 0, the bin count is always equal to
95 > the last bin plus 1.
96 > Set the this value to 0 if the bin count is unknown (the default).
97   The most recent
98 < .I \-b
98 > .I \-b,
99 > .I \-bn
100   and
101   .I \-o
102   options to the left of each
# Line 80 | Line 115 | the variables Px, Py, and Pz, and the normalized ray d
115   will be assigned to Dx, Dy, and Dz.
116   These parameters may be combined with definitions given in
117   .I \-e
118 < options and files read in
118 > arguments and files read using the
119   .I \-f
120 < options, to compute the bin, which will be
120 > option.
121 > The computed bin value will be
122   rounded to the nearest whole number.
123   This mechanism allows the user to define precise regions or directions
124   they wish to accumulate, such as the Tregenza sky discretization,
125   which would be otherwise impossible to specify
126   as a set of RADIANCE primitives.
127 + The rules and predefined functions available for these expressions are
128 + described in the
129 + .I rcalc(1)
130 + man page.
131 + Unlike
132 + .I rcalc,
133 + .I rtcontrib
134 + will search the RADIANCE library directories for each file given in a
135 + .I \-f
136 + option.
137   .PP
138   If no
139   .I \-o
140   specification is given, results are written on the standard output in order
141   of modifier (as given on the command line) then bin number.
142 < Concatenated data is also sent to a lone output file (i.e., an initial
142 > Concatenated data is also sent to a single destination (i.e., an initial
143   .I \-o
144   specification without formatting strings).
145   If a "%s" format appears but no "%d" in the
# Line 168 | Line 214 | pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.p
214   .PP
215   To compute an array of illuminance contributions according to a Tregenza sky:
216   .IP "" .2i
217 < rtcontrib -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
217 > rtcontrib -I+ -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
218   @render.opt -f tregenza.cal scene.oct < test.dat
219 + .SH ENVIRONMENT
220 + RAYPATH         path to search for -f and -M files
221   .SH AUTHOR
222   Greg Ward
223   .SH "SEE ALSO"

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