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Comparing ray/doc/man/man1/rtcontrib.1 (file contents):
Revision 1.17 by greg, Sat Nov 17 01:13:50 2007 UTC vs.
Revision 1.22 by greg, Sun Jun 14 18:21:58 2009 UTC

# Line 9 | Line 9 | rtcontrib - compute contribution coefficients in a RAD
9   ][
10   .B \-V
11   ][
12 < .B \-c
12 > .B "\-c count"
13   ][
14   .B \-fo
15   |
# Line 58 | Line 58 | this file.
58   (No search takes place if a file name begins with a '.', '/' or '~'
59   character.)\0
60   .PP
61 + If the
62 + .I \-n
63 + option is specified with a value greater than 1, multiple
64 + .I rtrace
65 + processes will be used to accelerate computation on a shared
66 + memory machine.
67 + Note that there is no benefit to using more processes
68 + than there are local CPUs available to do the work, and the
69 + .I rtcontrib
70 + process itself may use a considerable amount of CPU time.
71 + .PP
72   By setting the boolean
73   .I \-V
74   option, you may instruct
# Line 86 | Line 97 | rather than radiance, and
97   .I \-V-
98   coefficients contain an additonal factor of PI.
99   .PP
100 + The
101 + .I \-c
102 + option tells
103 + .I rtcontrib
104 + how many rays to accumulate for each record.
105 + The default value is 1, meaning a full record will be produced for
106 + each input ray.
107 + For values greater than 1, contributions will be averaged together
108 + over the given number of input rays.
109 + If set to zero, only a single record will be produced at the very
110 + end, corresponding to the sum of all rays given on the input
111 + (rather than the average).
112 + This is equivalent to passing all the output records through a program like
113 + .I total(1)
114 + to sum RGB values together, but is much more efficient.
115 + Using this option, it is possible to reverse sampling, sending rays from
116 + a parallel source such as the sun to a diffuse surface, for example.
117 + Note that output flushing via zero-direction rays is disabled
118 + for accumulated evaluations.
119 + .PP
120   The output of
121   .I rtcontrib
122   has many potential uses.
# Line 97 | Line 128 | More generally,
128   can be used to compute arbitrary input-output relationships in optical
129   systems, such as luminaires, light pipes, and shading devices.
130   .PP
100 – Setting the
101 – .I \-c
102 – option instructs
103 – .I rtcontrib
104 – to accumulate values rather than reporting one record per ray.
105 – With this option, only a single record will be produced at the very
106 – end, corresponding to the sum of all rays given on the input.
107 – This is equivalent to passing all the output records through a program like
108 – .I total(1)
109 – to sum RGB values together, but is much more efficient.
110 – Using this option, it is possible to reverse sampling, sending rays from
111 – a parallel source such as the sun to a diffuse surface, for example.
112 – Care must be taken to perform normalization based on the
113 – radiation density and the number of rays sampled.
114 – .PP
131   .I Rtcontrib
132   calls
133   .I rtrace(1)
# Line 130 | Line 146 | If instead the
146   .I \-r
147   option is specified, data recovery is attempted on existing files.
148   (If
149 < .I \-c
149 > .I "\-c 0"
150   is used together with the
151   .I \-r
152   option, existing files are read in and new ray evaluations are added
# Line 150 | Line 166 | If the number of bins is known in advance, it should b
166   .I \-bn
167   option, and this is critical for output files containing multiple values
168   per record.
169 + A variable or constant name may be given for this parameter if
170 + it has been defined via a previous
171 + .I \-f
172 + or
173 + .I \-e
174 + option.
175   Since bin numbers start from 0, the bin count is always equal to
176   the last bin plus 1.
177   Set the this value to 0 if the bin count is unknown (the default).
# Line 160 | Line 182 | and
182   .I \-o
183   options to the left of each
184   .I \-m
185 < setting affect only that modifier.
185 > setting are the ones used for that modifier.
186   The ordering of other options is unimportant, except for
187   .I \-x
188   and
189   .I \-y
190   if the
191   .I \-c
192 < is present, when they control the resolution string
192 > is 0, when they control the resolution string
193   produced in the corresponding output.
194   .PP
195   If a
# Line 243 | Line 265 | suitable for manipulation with
265   .I pcomb(1)
266   and related tools.
267   .PP
246 – If the
247 – .I \-n
248 – option is specified with a value greater than 1, multiple
249 – .I rtrace
250 – processes will be used to accelerate computation on a shared
251 – memory machine.
252 – Note that there is no benefit to using more processes
253 – than there are local CPUs available to do the work, and the
254 – .I rtcontrib
255 – process itself may use a considerable amount of CPU time.
256 – .PP
268   Options may be given on the command line and/or read from the
269   environment and/or read from a file.
270   A command argument beginning with a dollar sign ('$') is immediately
# Line 271 | Line 282 | contributions:
282   .IP "" .2i
283   vwrays \-ff \-x 1024 \-y 1024 \-vf best.vf |
284   rtcontrib \-ffc `vwrays \-d \-x 1024 \-y 1024 \-vf best.vf`
285 < @render.opt \-o c_%s.pic \-m light1 \-m light2 scene.oct
285 > @render.opt \-o c_%s.hdr \-m light1 \-m light2 scene.oct
286   .PP
287   These images may then be recombined using the desired outputs
288   of light1 and light2:
289   .IP "" .2i
290 < pcomb \-c 100 90 75 c_light1.pic \-c 50 55 57 c_light2.pic > combined.pic
290 > pcomb \-c 100 90 75 c_light1.hdr \-c 50 55 57 c_light2.hdr > combined.hdr
291   .PP
292   To compute an array of illuminance contributions according to a Tregenza sky:
293   .IP "" .2i
# Line 287 | Line 298 | RAYPATH                path to search for \-f and \-M files
298   .SH AUTHOR
299   Greg Ward
300   .SH "SEE ALSO"
301 < cnt(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
301 > cnt(1), genklemsamp(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
302   rcalc(1), rpict(1), rtrace(1), total(1), vwrays(1), ximage(1)

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