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Revision 1.2 by greg, Fri Apr 18 17:29:21 2003 UTC vs.
Revision 1.25 by greg, Sat Jan 25 18:27:39 2014 UTC

# Line 1 | Line 1
1 < .\" RCSid "$Id"
1 > .\" RCSid "$Id$"
2   .TH RTRACE 1 10/17/97 RADIANCE
3   .SH NAME
4   rtrace - trace rays in RADIANCE scene
# Line 30 | Line 30 | Input for each ray is:
30   If the direction vector is (0,0,0), a bogus record
31   is printed and the output is flushed if the
32   .I -x
33 < value is unset or zero.
33 > value is one or zero.
34   (See the notes on this option below.)\0
35   This may be useful for programs that run
36   .I rtrace
# Line 87 | Line 87 | d      direction (normalized)
87   .IP
88   v       value (radiance)
89   .IP
90 + V       contribution (radiance)
91 + .IP
92   w       weight
93   .IP
94 + W       color coefficient
95 + .IP
96   l       effective length of ray
97   .IP
98   L       first intersection distance
# Line 105 | Line 109 | s      surface name
109   .IP
110   m       modifier name
111   .IP
112 + M       material name
113 + .IP
114 + ~       tilde (end of trace marker)
115 + .IP
116   If the letter 't' appears in
117   .I spec,
118   then the fields following will be printed for every ray traced,
119   not just the final result.
120 + If the capital letter 'T' is given instead of 't', then all rays will
121 + be reported, including shadow testing rays to light sources.
122   Spawned rays are indented one tab for each level.
123 + The tilde marker ('~') is a handy way of differentiating the final ray
124 + value from daughter values in a traced ray tree, and usually appears
125 + right before the 't' or 'T' output flags.
126 + E.g.,
127 + .I \-ov~TmW
128 + will emit a tilde followed by a tab at the end of each trace,
129 + which can be easily distinguished even in binary output.
130   .IP
131   Note that there is no space between this option and its argument.
132   .TP
133 < .BI -te \ mat
133 > .BI -te \ mod
134   Append
135 < .I mat
135 > .I mod
136   to the trace exclude list,
137   so that it will not be reported by the trace option
138   .I (\-o*t*).
139   Any ray striking an object having
140 < .I mat
140 > .I mod
141   as its modifier will not be reported to the standard output with
142   the rest of the rays being traced.
143 < This option has no effect unless the 't' option has been given as
144 < part of the output specifier.
145 < Any number of excluded materials may be given, but each
143 > This option has no effect unless either the 't' or 'T'
144 > option has been given as part of the output specifier.
145 > Any number of excluded modifiers may be given, but each
146   must appear in a separate option.
147   .TP
148 < .BI -ti \ mat
148 > .BI -ti \ mod
149   Add
150 < .I mat
150 > .I mod
151   to the trace include list,
152 < so that it will be considered during the indirect calculation.
152 > so that it will be reported by the trace option.
153   The program can use either an include list or an exclude
154   list, but not both.
155   .TP
156   .BI -tE \ file
157   Same as
158   .I \-te,
159 < except read materials to be excluded from
159 > except read modifiers to be excluded from
160   .I file.
161   The RAYPATH environment variable determines which directories are
162   searched for this file.
163 < The material names are separated by white space in the file.
163 > The modifier names are separated by white space in the file.
164   .TP
165   .BI -tI \ file
166   Same as
167   .I \-ti,
168 < except read materials to be included from
168 > except read modifiers to be included from
169   .I file.
170   .TP
171   .BR \-i
# Line 163 | Line 180 | option (below) may be used to override this.
180   This option is especially useful in
181   conjunction with ximage(1) for computing illuminance at scene points.
182   .TP
183 + .BR \-u
184 + Boolean switch to control uncorrelated random sampling.
185 + When "off", a low-discrepancy sequence is used, which reduces
186 + variance but can result in a brushed appearance in specular highlights.
187 + When "on", pure Monte Carlo sampling is used in all calculations.
188 + .TP
189   .BR \-I
190   Boolean switch to compute irradiance rather than radiance,
191   with the input origin and direction interpreted instead
# Line 176 | Line 199 | Set the x resolution to
199   .I res.
200   The output will be flushed after every
201   .I res
202 < input rays.
202 > input rays if
203 > .I \-y
204 > is set to zero.
205 > A value of one means that every ray will be flushed, whatever
206 > the setting of
207 > .I \-y.
208   A value of zero means that no output flushing will take place.
209   .TP
210   .BI -y \ res
# Line 207 | Line 235 | format.
235   .I \-f
236   option, above.)
237   .TP
238 + .BI -n \ nproc
239 + Execute in parallel on
240 + .I nproc
241 + local processes.
242 + This option is incompatible with the
243 + .I \-P
244 + and
245 + .I \-PP,
246 + options.
247 + Multiple processes also do not work properly with ray tree output
248 + using any of the
249 + .I \-o*t*
250 + options.
251 + There is no benefit from specifying more processes than there are
252 + cores available on the system or the
253 + .I \-x
254 + setting, which forces a wait at each flush.
255 + .TP
256   .BI -dj \ frac
257   Set the direct jittering to
258   .I frac.
# Line 289 | Line 335 | may also be desirable in conjunction with the
335   .I \-i
336   option.
337   .TP
338 < .BI -sj \ frac
339 < Set the specular sampling jitter to
340 < .I frac.
341 < This is the degree to which the highlights are sampled
342 < for rough specular materials.
343 < A value of one means that all highlights will be fully sampled
344 < using distributed ray tracing.
338 > .BI -ss \ samp
339 > Set the specular sampling to
340 > .I samp.
341 > For values less than 1, this is the degree to which the highlights
342 > are sampled for rough specular materials.
343 > A value greater than one causes multiple ray samples to be sent
344 > to reduce noise at a commmesurate cost.
345   A value of zero means that no jittering will take place, and all
346   reflections will appear sharp even when they should be diffuse.
347   .TP
# Line 315 | Line 361 | accuracy and rendering time.
361   .TP
362   .BR -bv
363   Boolean switch for back face visibility.
364 < With this switch off, back faces of opaque objects will be invisible
365 < to all rays.
364 > With this switch off, back faces of all objects will be invisible
365 > to view rays.
366   This is dangerous unless the model was constructed such that
367 < all surface normals on opaque objects face outward.
367 > all surface normals face outward.
368   Although turning off back face visibility does not save much
369   computation time under most circumstances, it may be useful as a
370   tool for scene debugging, or for seeing through one-sided walls from
371   the outside.
326 – This option has no effect on transparent or translucent materials.
372   .TP
373   .BI -av " red grn blu"
374   Set the ambient value to a radiance of
# Line 427 | Line 472 | header of the ambient file.
472   .I Getinfo(1)
473   may be used to print out this information.
474   .TP
475 < .BI -ae \ mat
475 > .BI -ae \ mod
476   Append
477 < .I mat
477 > .I mod
478   to the ambient exclude list,
479   so that it will not be considered during the indirect calculation.
480   This is a hack for speeding the indirect computation by
481   ignoring certain objects.
482   Any object having
483 < .I mat
483 > .I mod
484   as its modifier will get the default ambient
485   level rather than a calculated value.
486 < Any number of excluded materials may be given, but each
486 > Any number of excluded modifiers may be given, but each
487   must appear in a separate option.
488   .TP
489 < .BI -ai \ mat
489 > .BI -ai \ mod
490   Add
491 < .I mat
491 > .I mod
492   to the ambient include list,
493   so that it will be considered during the indirect calculation.
494   The program can use either an include list or an exclude
# Line 452 | Line 497 | list, but not both.
497   .BI -aE \ file
498   Same as
499   .I \-ae,
500 < except read materials to be excluded from
500 > except read modifiers to be excluded from
501   .I file.
502   The RAYPATH environment variable determines which directories are
503   searched for this file.
504 < The material names are separated by white space in the file.
504 > The modifier names are separated by white space in the file.
505   .TP
506   .BI -aI \ file
507   Same as
508   .I \-ai,
509 < except read materials to be included from
509 > except read modifiers to be included from
510   .I file.
511   .TP
512   .BI -me " rext gext bext"
# Line 502 | Line 547 | source within a given scattering volume.
547   .TP
548   .BI -lr \ N
549   Limit reflections to a maximum of
550 < .I N.
550 > .I N,
551 > if N is a positive integer.
552 > If
553 > .I N
554 > is zero or negative, then Russian roulette is used for ray
555 > termination, and the
556 > .I -lw
557 > setting (below) must be positive.
558 > If N is a negative integer, then this sets the upper limit
559 > of reflections past which Russian roulette will be used.
560 > In scenes with dielectrics and total internal reflection,
561 > a setting of 0 (no limit) may cause a stack overflow.
562   .TP
563   .BI -lw \ frac
564   Limit the weight of each ray to a minimum of
565   .I frac.
566 < During ray-tracing, a record is kept of the final contribution
567 < a ray would have to the image.
568 < If it is less then the specified minimum, the ray is not traced.
566 > During ray-tracing, a record is kept of the estimated contribution
567 > (weight) a ray would have in the image.
568 > If this weight is less than the specified minimum and the
569 > .I -lr
570 > setting (above) is positive, the ray is not traced.
571 > Otherwise, Russian roulette is used to
572 > continue rays with a probability equal to the ray weight
573 > divided by the given
574 > .I frac.
575   .TP
576   .BR -ld
577   Boolean switch to limit ray distance.
# Line 573 | Line 635 | system call will share memory on a copy-on-write basis
635   .SH EXAMPLES
636   To compute radiance values for the rays listed in samples.inp:
637   .IP "" .2i
638 < rtrace -ov scene.oct < samples.inp > radiance.out
638 > rtrace \-ov scene.oct < samples.inp > radiance.out
639   .PP
640   To compute illuminance values at locations selected with the 't'
641   command of
642   .I ximage(1):
643   .IP "" .2i
644 < ximage scene.pic | rtrace -h -x 1 -i scene.oct | rcalc -e '$1=47.4*$1+120*$2+11.6*$3'
644 > ximage scene.hdr | rtrace \-h \-x 1 \-i scene.oct | rcalc \-e '$1=47.4*$1+120*$2+11.6*$3'
645   .PP
646   To record the object identifier corresponding to each pixel in an image:
647   .IP "" .2i
648 < vwrays -fd scene.pic | rtrace -fda `vwrays -d scene.pic` -os scene.oct
648 > vwrays \-fd scene.hdr | rtrace \-fda `vwrays \-d scene.hdr` \-os scene.oct
649   .PP
650   To compute an image with an unusual view mapping:
651   .IP "" .2i
652 < cnt 640 480 | rcalc -e 'xr:640;yr:480' -f unusual_view.cal | rtrace
653 < -x 640 -y 480 -fac scene.oct > unusual.pic
652 > cnt 480 640 | rcalc \-e 'xr:640;yr:480' \-f unusual_view.cal | rtrace
653 > \-x 640 \-y 480 \-fac scene.oct > unusual.hdr
654   .SH ENVIRONMENT
655   RAYPATH         the directories to check for auxiliary files.
656   .SH FILES
657 < /usr/tmp/rtXXXXXX               common header information for picture sequence
657 > /tmp/rtXXXXXX           common header information for picture sequence
658   .SH DIAGNOSTICS
659   If the program terminates from an input related error, the exit status
660   will be 1.
# Line 607 | Line 669 | option.
669   Greg Ward
670   .SH "SEE ALSO"
671   getinfo(1), lookamb(1), oconv(1), pfilt(1), pinterp(1),
672 < pvalue(1), rpict(1), rview(1), vwrays(1), ximage(1)
672 > pvalue(1), rpict(1), rcontrib(1), rvu(1), vwrays(1), ximage(1)

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