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Revision 1.1 by greg, Thu Jun 14 22:42:21 2012 UTC vs.
Revision 1.11 by greg, Tue Jul 22 21:55:31 2014 UTC

# Line 1 | Line 1
1   .\" RCSid "$Id$"
2 < .TH RTCONTRIB 1 5/25/05 RADIANCE
2 > .TH RCONTRIB 1 5/25/05 RADIANCE
3   .SH NAME
4   rcontrib - compute contribution coefficients in a RADIANCE scene
5   .SH SYNOPSIS
# Line 21 | Line 21 | rcontrib - compute contribution coefficients in a RADI
21   ][
22   .B "\-o ospec"
23   ][
24 + .B "\-p p1=V1,p2=V2"
25 + ][
26   .B "\-b binv"
27   ][
28   .B "\-bn nbins"
# Line 42 | Line 44 | rtrace options
44   .br
45   .B "rcontrib [ options ] \-defaults"
46   .SH DESCRIPTION
47 < .I Rtcontrib
47 > .I Rcontrib
48   computes ray coefficients
49   for objects whose modifiers are named in one or more
50   .I \-m
# Line 61 | Line 63 | character.)\0
63   If the
64   .I \-n
65   option is specified with a value greater than 1, multiple
64 – .I rtrace
66   processes will be used to accelerate computation on a shared
67   memory machine.
68   Note that there is no benefit to using more processes
# Line 102 | Line 103 | The
103   option tells
104   .I rcontrib
105   how many rays to accumulate for each record.
106 < The default value is 1, meaning a full record will be produced for
106 > The default value is one, meaning a full record will be produced for
107   each input ray.
108 < For values greater than 1, contributions will be averaged together
108 > For values greater than one, contributions will be averaged together
109   over the given number of input rays.
110   If set to zero, only a single record will be produced at the very
111   end, corresponding to the sum of all rays given on the input
# Line 114 | Line 115 | This is equivalent to passing all the output records t
115   to sum RGB values together, but is much more efficient.
116   Using this option, it is possible to reverse sampling, sending rays from
117   a parallel source such as the sun to a diffuse surface, for example.
118 < Note that output flushing via zero-direction rays is disabled
119 < for accumulated evaluations.
118 > Note that output flushing via zero-direction rays is disabled with
119 > .I \-c
120 > set to zero.
121   .PP
122   The output of
123   .I rcontrib
# Line 128 | Line 130 | More generally,
130   can be used to compute arbitrary input-output relationships in optical
131   systems, such as luminaires, light pipes, and shading devices.
132   .PP
133 < .I Rtcontrib
134 < calls
135 < .I rtrace(1)
134 < with the \-oTW (or \-oTV) option to calculate the daughter ray
135 < contributions for each input ray, and the output tallies
136 < are sent to one or more destinations according to the given
133 > .I Rcontrib
134 > sends the accumulated rays tallies
135 > to one or more destinations according to the given
136   .I \-o
137   specification.
138   If a destination begins with an exclamation mark ('!'), then
# Line 162 | Line 161 | this will be applied to a "%d" format in the output fi
161   specification if present.
162   The actual bin number is computed at run time based on ray direction
163   and surface intersection, as described below.
164 < If the number of bins is known in advance, it should be specified with the
164 > The number of bins must be specified in advance with the
165   .I \-bn
166   option, and this is critical for output files containing multiple values
167   per record.
# Line 172 | Line 171 | it has been defined via a previous
171   or
172   .I \-e
173   option.
174 < Since bin numbers start from 0, the bin count is always equal to
175 < the last bin plus 1.
177 < Set the this value to 0 if the bin count is unknown (the default).
174 > Since bin numbers start from zero, the bin count is always equal to
175 > the last bin plus one.
176   The most recent
177 + .I \-p,
178   .I \-b,
179   .I \-bn
180   and
# Line 189 | Line 188 | and
188   .I \-y
189   if the
190   .I \-c
191 < is 0, when they control the resolution string
191 > is zero, when they control the resolution string
192   produced in the corresponding output.
193   .PP
194   If a
195   .I \-b
196   expression is defined for a particular modifier,
197   the bin number will be evaluated at run time for each
198 < ray contribution from
200 < .I rtrace.
198 > ray contribution.
199   Specifically, each ray's world intersection point will be assigned to
200   the variables Px, Py, and Pz, and the normalized ray direction
201   will be assigned to Dx, Dy, and Dz.
# Line 206 | Line 204 | These parameters may be combined with definitions give
204   arguments and files read using the
205   .I \-f
206   option.
207 + Additional parameter values that apply only to this modifier may be specified
208 + with a
209 + .I \-p
210 + option, which contains a list of variable names and assigned values, separated
211 + by commas or semicolons.
212   The computed bin value will be
213   rounded to the nearest whole number.
214 + (Negative bin values will be silently ignored.)\0
215 + For a single bin, you may specify
216 + .I "\-b 0",
217 + which is the default.
218   This mechanism allows the user to define precise regions or directions
219   they wish to accumulate, such as the Tregenza sky discretization,
220   which would be otherwise impossible to specify
# Line 216 | Line 223 | The rules and predefined functions available for these
223   described in the
224   .I rcalc(1)
225   man page.
226 < Unlike
226 > Like
227   .I rcalc,
228   .I rcontrib
229   will search the RADIANCE library directories for each file given in a
# Line 291 | Line 298 | pcomb \-c 100 90 75 c_light1.hdr \-c 50 55 57 c_light2
298   .PP
299   To compute an array of illuminance contributions according to a Tregenza sky:
300   .IP "" .2i
301 < rcontrib \-I+ \-b tbin \-o sky.dat \-m skyglow \-b 0 \-o ground.dat \-m groundglow
302 < @render.opt \-f tregenza.cal scene.oct < test.dat
301 > rcontrib \-I+ \-f tregenza.cal \-b tbin \-bn Ntbins \-o sky.dat \-m skyglow
302 > \-b 0 \-o ground.dat \-m groundglow @render.opt scene.oct < test.dat
303   .SH ENVIRONMENT
304   RAYPATH         path to search for \-f and \-M files
305   .SH AUTHOR
306   Greg Ward
307   .SH "SEE ALSO"
308   cnt(1), genklemsamp(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
309 < rcalc(1), rpict(1), rsensor(1), rtrace(1), total(1), vwrays(1), ximage(1)
309 > rcalc(1), rfluxmtx(1), rmtxop(1),
310 > rpict(1), rsensor(1), rtrace(1), total(1), vwrays(1), ximage(1)

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