| 16 |
|
.B octree |
| 17 |
|
.br |
| 18 |
|
.B "rtrace [ options ] \-defaults" |
| 19 |
+ |
.br |
| 20 |
+ |
.B "rtrace \-features [feat1 ..]" |
| 21 |
|
.SH DESCRIPTION |
| 22 |
|
.I Rtrace |
| 23 |
|
traces rays from the standard input through the RADIANCE scene given by |
| 32 |
|
If the direction vector is (0,0,0), a bogus record |
| 33 |
|
is printed and the output is flushed if the |
| 34 |
|
.I -x |
| 35 |
< |
value is unset or zero. |
| 35 |
> |
value is one or zero. |
| 36 |
|
(See the notes on this option below.)\0 |
| 37 |
|
This may be useful for programs that run |
| 38 |
|
.I rtrace |
| 39 |
|
as a separate process. |
| 40 |
< |
In the second form, the default values |
| 40 |
> |
.PP |
| 41 |
> |
In the second form shown above, the default values |
| 42 |
|
for the options (modified by those options present) |
| 43 |
|
are printed with a brief explanation. |
| 44 |
|
.PP |
| 45 |
+ |
In the third form, a list of supported features is sent |
| 46 |
+ |
to the standard output, one per line. |
| 47 |
+ |
If additional arguments follow, they are checked for presence in |
| 48 |
+ |
this list. |
| 49 |
+ |
If a feature includes subfeatures, these may be checked as well by |
| 50 |
+ |
specifying: |
| 51 |
+ |
.nf |
| 52 |
+ |
|
| 53 |
+ |
rtrace -features FeatName=subfeat1,subfeat2 |
| 54 |
+ |
|
| 55 |
+ |
.fi |
| 56 |
+ |
If any named feature or subfeature is missing, an error is |
| 57 |
+ |
reported and the program returns an error status. |
| 58 |
+ |
If all of the named features are present, a zero status is returned. |
| 59 |
+ |
.PP |
| 60 |
|
Options may be given on the command line and/or read from the |
| 61 |
|
environment and/or read from a file. |
| 62 |
|
A command argument beginning with a dollar sign ('$') is immediately |
| 86 |
|
ascii, 'f' for single-precision floating point, |
| 87 |
|
and 'd' for double-precision floating point. |
| 88 |
|
In addition to these three choices, the character 'c' may be used |
| 89 |
< |
to denote 4-byte floating point (Radiance) color format |
| 90 |
< |
for the output of values only |
| 91 |
< |
.I (\-ov |
| 92 |
< |
option, below). |
| 89 |
> |
to denote 4-byte RGBE (Radiance) color format |
| 90 |
> |
for the output of individual color values only, and the |
| 91 |
> |
.I \-x |
| 92 |
> |
and |
| 93 |
> |
.I \-y |
| 94 |
> |
options should also be specified to create a valid output picture. |
| 95 |
|
If the output character is missing, the input format is used. |
| 96 |
|
.IP |
| 97 |
|
Note that there is no space between this option and its argument. |
| 107 |
|
.IP |
| 108 |
|
v value (radiance) |
| 109 |
|
.IP |
| 110 |
+ |
V contribution (radiance) |
| 111 |
+ |
.IP |
| 112 |
|
w weight |
| 113 |
|
.IP |
| 114 |
+ |
W color coefficient |
| 115 |
+ |
.IP |
| 116 |
|
l effective length of ray |
| 117 |
|
.IP |
| 118 |
|
L first intersection distance |
| 129 |
|
.IP |
| 130 |
|
m modifier name |
| 131 |
|
.IP |
| 132 |
+ |
M material name |
| 133 |
+ |
.IP |
| 134 |
+ |
r mirrored value contribution |
| 135 |
+ |
.IP |
| 136 |
+ |
x unmirrored value contribution |
| 137 |
+ |
.IP |
| 138 |
+ |
R mirrored ray length |
| 139 |
+ |
.IP |
| 140 |
+ |
X unmirrored ray length |
| 141 |
+ |
.IP |
| 142 |
+ |
~ tilde (end of trace marker) |
| 143 |
+ |
.IP |
| 144 |
|
If the letter 't' appears in |
| 145 |
|
.I spec, |
| 146 |
|
then the fields following will be printed for every ray traced, |
| 147 |
|
not just the final result. |
| 148 |
+ |
If the capital letter 'T' is given instead of 't', then all rays will |
| 149 |
+ |
be reported, including shadow testing rays to light sources. |
| 150 |
|
Spawned rays are indented one tab for each level. |
| 151 |
+ |
The tilde marker ('~') is a handy way of differentiating the final ray |
| 152 |
+ |
value from daughter values in a traced ray tree, and usually appears |
| 153 |
+ |
right before the 't' or 'T' output flags. |
| 154 |
+ |
E.g., |
| 155 |
+ |
.I \-ov~TmW |
| 156 |
+ |
will emit a tilde followed by a tab at the end of each trace, |
| 157 |
+ |
which can be easily distinguished even in binary output. |
| 158 |
|
.IP |
| 159 |
|
Note that there is no space between this option and its argument. |
| 160 |
|
.TP |
| 161 |
< |
.BI -te \ mat |
| 161 |
> |
.BI -te \ mod |
| 162 |
|
Append |
| 163 |
< |
.I mat |
| 163 |
> |
.I mod |
| 164 |
|
to the trace exclude list, |
| 165 |
|
so that it will not be reported by the trace option |
| 166 |
|
.I (\-o*t*). |
| 167 |
|
Any ray striking an object having |
| 168 |
< |
.I mat |
| 168 |
> |
.I mod |
| 169 |
|
as its modifier will not be reported to the standard output with |
| 170 |
|
the rest of the rays being traced. |
| 171 |
< |
This option has no effect unless the 't' option has been given as |
| 172 |
< |
part of the output specifier. |
| 173 |
< |
Any number of excluded materials may be given, but each |
| 171 |
> |
This option has no effect unless either the 't' or 'T' |
| 172 |
> |
option has been given as part of the output specifier. |
| 173 |
> |
Any number of excluded modifiers may be given, but each |
| 174 |
|
must appear in a separate option. |
| 175 |
|
.TP |
| 176 |
< |
.BI -ti \ mat |
| 176 |
> |
.BI -ti \ mod |
| 177 |
|
Add |
| 178 |
< |
.I mat |
| 178 |
> |
.I mod |
| 179 |
|
to the trace include list, |
| 180 |
< |
so that it will be considered during the indirect calculation. |
| 180 |
> |
so that it will be reported by the trace option. |
| 181 |
|
The program can use either an include list or an exclude |
| 182 |
|
list, but not both. |
| 183 |
|
.TP |
| 184 |
|
.BI -tE \ file |
| 185 |
|
Same as |
| 186 |
|
.I \-te, |
| 187 |
< |
except read materials to be excluded from |
| 187 |
> |
except read modifiers to be excluded from |
| 188 |
|
.I file. |
| 189 |
|
The RAYPATH environment variable determines which directories are |
| 190 |
|
searched for this file. |
| 191 |
< |
The material names are separated by white space in the file. |
| 191 |
> |
The modifier names are separated by white space in the file. |
| 192 |
|
.TP |
| 193 |
|
.BI -tI \ file |
| 194 |
|
Same as |
| 195 |
|
.I \-ti, |
| 196 |
< |
except read materials to be included from |
| 196 |
> |
except read modifiers to be included from |
| 197 |
|
.I file. |
| 198 |
|
.TP |
| 199 |
|
.BR \-i |
| 206 |
|
.I \-dv |
| 207 |
|
option (below) may be used to override this. |
| 208 |
|
This option is especially useful in |
| 209 |
< |
conjunction with ximage(1) for computing illuminance at scene points. |
| 209 |
> |
conjunction with ximage(1) for computing irradiance at scene points. |
| 210 |
|
.TP |
| 211 |
+ |
.BR \-u |
| 212 |
+ |
Boolean switch to control uncorrelated random sampling. |
| 213 |
+ |
When "off", a low-discrepancy sequence is used, which reduces |
| 214 |
+ |
variance but can result in a brushed appearance in specular highlights. |
| 215 |
+ |
When "on", pure Monte Carlo sampling is used in all calculations. |
| 216 |
+ |
.TP |
| 217 |
|
.BR \-I |
| 218 |
|
Boolean switch to compute irradiance rather than radiance, |
| 219 |
|
with the input origin and direction interpreted instead |
| 227 |
|
.I res. |
| 228 |
|
The output will be flushed after every |
| 229 |
|
.I res |
| 230 |
< |
input rays. |
| 230 |
> |
input rays if |
| 231 |
> |
.I \-y |
| 232 |
> |
is set to zero. |
| 233 |
> |
A value of one means that every ray will be flushed, whatever |
| 234 |
> |
the setting of |
| 235 |
> |
.I \-y. |
| 236 |
|
A value of zero means that no output flushing will take place. |
| 237 |
|
.TP |
| 238 |
|
.BI -y \ res |
| 263 |
|
.I \-f |
| 264 |
|
option, above.) |
| 265 |
|
.TP |
| 266 |
+ |
.BI -n \ nproc |
| 267 |
+ |
Execute in parallel on |
| 268 |
+ |
.I nproc |
| 269 |
+ |
local processes. |
| 270 |
+ |
This option is incompatible with the |
| 271 |
+ |
.I \-P |
| 272 |
+ |
and |
| 273 |
+ |
.I \-PP, |
| 274 |
+ |
options. |
| 275 |
+ |
Multiple processes also do not work properly with ray tree output |
| 276 |
+ |
using any of the |
| 277 |
+ |
.I \-o*t* |
| 278 |
+ |
options. |
| 279 |
+ |
There is no benefit from specifying more processes than there are |
| 280 |
+ |
cores available on the system or the |
| 281 |
+ |
.I \-x |
| 282 |
+ |
setting, which forces a wait at each flush. |
| 283 |
+ |
.TP |
| 284 |
|
.BI -dj \ frac |
| 285 |
|
Set the direct jittering to |
| 286 |
|
.I frac. |
| 335 |
|
specification will be calculated. |
| 336 |
|
.TP |
| 337 |
|
.BI -dr \ N |
| 338 |
< |
Set the number of relays for secondary sources to |
| 338 |
> |
Set the number of relays for virtual sources to |
| 339 |
|
.I N. |
| 340 |
< |
A value of 0 means that secondary sources will be ignored. |
| 340 |
> |
A value of 0 means that virtual sources will be ignored. |
| 341 |
|
A value of 1 means that sources will be made into first generation |
| 342 |
< |
secondary sources; a value of 2 means that first generation |
| 343 |
< |
secondary sources will also be made into second generation secondary |
| 342 |
> |
virtual sources; a value of 2 means that first generation |
| 343 |
> |
virtual sources will also be made into second generation virtual |
| 344 |
|
sources, and so on. |
| 345 |
|
.TP |
| 346 |
|
.BI -dp \ D |
| 347 |
< |
Set the secondary source presampling density to D. |
| 347 |
> |
Set the virtual source presampling density to D. |
| 348 |
|
This is the number of samples per steradian |
| 349 |
|
that will be used to determine ahead of time whether or not |
| 350 |
|
it is worth following shadow rays through all the reflections and/or |
| 351 |
< |
transmissions associated with a secondary source path. |
| 352 |
< |
A value of 0 means that the full secondary source path will always |
| 351 |
> |
transmissions associated with a virtual source path. |
| 352 |
> |
A value of 0 means that the full virtual source path will always |
| 353 |
|
be tested for shadows if it is tested at all. |
| 354 |
|
.TP |
| 355 |
|
.BR \-dv |
| 363 |
|
.I \-i |
| 364 |
|
option. |
| 365 |
|
.TP |
| 366 |
< |
.BI -sj \ frac |
| 367 |
< |
Set the specular sampling jitter to |
| 368 |
< |
.I frac. |
| 369 |
< |
This is the degree to which the highlights are sampled |
| 370 |
< |
for rough specular materials. |
| 371 |
< |
A value of one means that all highlights will be fully sampled |
| 372 |
< |
using distributed ray tracing. |
| 366 |
> |
.BI -ss \ samp |
| 367 |
> |
Set the specular sampling to |
| 368 |
> |
.I samp. |
| 369 |
> |
For values less than 1, this is the degree to which the highlights |
| 370 |
> |
are sampled for rough specular materials. |
| 371 |
> |
A value greater than one causes multiple ray samples to be sent |
| 372 |
> |
to reduce noise at a commmesurate cost. |
| 373 |
|
A value of zero means that no jittering will take place, and all |
| 374 |
|
reflections will appear sharp even when they should be diffuse. |
| 375 |
|
.TP |
| 389 |
|
.TP |
| 390 |
|
.BR -bv |
| 391 |
|
Boolean switch for back face visibility. |
| 392 |
< |
With this switch off, back faces of opaque objects will be invisible |
| 393 |
< |
to all rays. |
| 392 |
> |
With this switch off, back faces of all objects will be invisible |
| 393 |
> |
to view rays. |
| 394 |
|
This is dangerous unless the model was constructed such that |
| 395 |
< |
all surface normals on opaque objects face outward. |
| 395 |
> |
all surface normals face outward. |
| 396 |
|
Although turning off back face visibility does not save much |
| 397 |
|
computation time under most circumstances, it may be useful as a |
| 398 |
|
tool for scene debugging, or for seeing through one-sided walls from |
| 399 |
|
the outside. |
| 326 |
– |
This option has no effect on transparent or translucent materials. |
| 400 |
|
.TP |
| 401 |
|
.BI -av " red grn blu" |
| 402 |
|
Set the ambient value to a radiance of |
| 429 |
|
.BI -ab \ N |
| 430 |
|
Set the number of ambient bounces to |
| 431 |
|
.I N. |
| 432 |
< |
This is the maximum number of diffuse bounces |
| 433 |
< |
computed by the indirect calculation. |
| 434 |
< |
A value of zero implies no indirect calculation. |
| 432 |
> |
This is the maximum number of diffuse bounces computed by the indirect |
| 433 |
> |
calculation. A value of zero implies no indirect calculation. |
| 434 |
> |
.IP |
| 435 |
> |
This value defaults to 1 in photon mapping mode (see |
| 436 |
> |
.I -ap |
| 437 |
> |
below), implying that global photon irradiance is always computed via |
| 438 |
> |
.I one |
| 439 |
> |
ambient bounce; this behaviour applies to any positive number of ambient |
| 440 |
> |
bounces, regardless of the actual value specified. A negative value enables |
| 441 |
> |
a preview mode that directly visualises the irradiance from the global |
| 442 |
> |
photon map without any ambient bounces. |
| 443 |
|
.TP |
| 444 |
|
.BI -ar \ res |
| 445 |
|
Set the ambient resolution to |
| 462 |
|
Set the ambient accuracy to |
| 463 |
|
.I acc. |
| 464 |
|
This value will approximately equal the error |
| 465 |
< |
from indirect illuminance interpolation. |
| 465 |
> |
from indirect irradiance interpolation. |
| 466 |
|
A value of zero implies no interpolation. |
| 467 |
|
.TP |
| 468 |
|
.BI -ad \ N |
| 469 |
|
Set the number of ambient divisions to |
| 470 |
|
.I N. |
| 471 |
|
The error in the Monte Carlo calculation of indirect |
| 472 |
< |
illuminance will be inversely proportional to the square |
| 472 |
> |
irradiance will be inversely proportional to the square |
| 473 |
|
root of this number. |
| 474 |
|
A value of zero implies no indirect calculation. |
| 475 |
|
.TP |
| 482 |
|
.BI -af \ fname |
| 483 |
|
Set the ambient file to |
| 484 |
|
.I fname. |
| 485 |
< |
This is where indirect illuminance will be stored and retrieved. |
| 486 |
< |
Normally, indirect illuminance values are kept in memory and |
| 485 |
> |
This is where indirect irradiance will be stored and retrieved. |
| 486 |
> |
Normally, indirect irradiance values are kept in memory and |
| 487 |
|
lost when the program finishes or dies. |
| 488 |
< |
By using a file, different invocations can share illuminance |
| 488 |
> |
By using a file, different invocations can share irradiance |
| 489 |
|
values, saving time in the computation. |
| 490 |
|
The ambient file is in a machine-independent binary format |
| 491 |
|
which can be examined with |
| 508 |
|
.I Getinfo(1) |
| 509 |
|
may be used to print out this information. |
| 510 |
|
.TP |
| 511 |
< |
.BI -ae \ mat |
| 511 |
> |
.BI -ae \ mod |
| 512 |
|
Append |
| 513 |
< |
.I mat |
| 513 |
> |
.I mod |
| 514 |
|
to the ambient exclude list, |
| 515 |
|
so that it will not be considered during the indirect calculation. |
| 516 |
|
This is a hack for speeding the indirect computation by |
| 517 |
|
ignoring certain objects. |
| 518 |
|
Any object having |
| 519 |
< |
.I mat |
| 519 |
> |
.I mod |
| 520 |
|
as its modifier will get the default ambient |
| 521 |
|
level rather than a calculated value. |
| 522 |
< |
Any number of excluded materials may be given, but each |
| 522 |
> |
Any number of excluded modifiers may be given, but each |
| 523 |
|
must appear in a separate option. |
| 524 |
|
.TP |
| 525 |
< |
.BI -ai \ mat |
| 525 |
> |
.BI -ai \ mod |
| 526 |
|
Add |
| 527 |
< |
.I mat |
| 527 |
> |
.I mod |
| 528 |
|
to the ambient include list, |
| 529 |
|
so that it will be considered during the indirect calculation. |
| 530 |
|
The program can use either an include list or an exclude |
| 533 |
|
.BI -aE \ file |
| 534 |
|
Same as |
| 535 |
|
.I \-ae, |
| 536 |
< |
except read materials to be excluded from |
| 536 |
> |
except read modifiers to be excluded from |
| 537 |
|
.I file. |
| 538 |
|
The RAYPATH environment variable determines which directories are |
| 539 |
|
searched for this file. |
| 540 |
< |
The material names are separated by white space in the file. |
| 540 |
> |
The modifier names are separated by white space in the file. |
| 541 |
|
.TP |
| 542 |
|
.BI -aI \ file |
| 543 |
|
Same as |
| 544 |
|
.I \-ai, |
| 545 |
< |
except read materials to be included from |
| 545 |
> |
except read modifiers to be included from |
| 546 |
|
.I file. |
| 547 |
|
.TP |
| 548 |
+ |
.BI -ap " file [bwidth1 [bwidth2]]" |
| 549 |
+ |
Enable photon mapping mode. Loads a photon map generated with |
| 550 |
+ |
.I mkpmap(1) |
| 551 |
+ |
from |
| 552 |
+ |
.I file, |
| 553 |
+ |
and evaluates the indirect irradiance depending on the photon type |
| 554 |
+ |
(automagically detected) using density estimates with a bandwidth of |
| 555 |
+ |
.I bwidth1 |
| 556 |
+ |
photons, or the default bandwidth if none is specified (a warning will be |
| 557 |
+ |
issued in this case). |
| 558 |
+ |
.IP |
| 559 |
+ |
Global photon irradiance is evaluated as part of the ambient calculation (see |
| 560 |
+ |
.I \-ab |
| 561 |
+ |
above), caustic photon irradiance is evaluated at primary rays, and |
| 562 |
+ |
indirect inscattering in |
| 563 |
+ |
.I mist |
| 564 |
+ |
is accounted for by volume photons. Contribution photons are treated as |
| 565 |
+ |
global photons by |
| 566 |
+ |
.I rtrace. |
| 567 |
+ |
.IP |
| 568 |
+ |
Additionally specifying |
| 569 |
+ |
.I bwidth2 |
| 570 |
+ |
enables bias compensation for the density estimates with a |
| 571 |
+ |
minimum and maximum bandwidth of |
| 572 |
+ |
.I bwidth1 |
| 573 |
+ |
and |
| 574 |
+ |
.I bwidth2, |
| 575 |
+ |
respectively. |
| 576 |
+ |
.IP |
| 577 |
+ |
Global photon irradiance may be optionally precomputed by |
| 578 |
+ |
.I mkpmap(1), |
| 579 |
+ |
in which case the bandwidth, if specified, is ignored, as the nearest photon |
| 580 |
+ |
is invariably looked up. |
| 581 |
+ |
.IP |
| 582 |
+ |
Using direct photons replaces the direct calculation with density estimates |
| 583 |
+ |
for debugging and validation of photon emission. |
| 584 |
+ |
.TP |
| 585 |
+ |
.BI -am " frac" |
| 586 |
+ |
Maximum search radius for photon map lookups. Without this option, an |
| 587 |
+ |
initial maximum search radius is estimated for each photon map from the |
| 588 |
+ |
average photon distance to the distribution's centre of gravity. It is then |
| 589 |
+ |
adapted to the photon density in subsequent lookups. This option imposes a |
| 590 |
+ |
global fixed maximum search radius for |
| 591 |
+ |
.I all |
| 592 |
+ |
photon maps, thus defeating the automatic adaptation. It is useful when |
| 593 |
+ |
multiple warnings about short photon lookups are issued. Note that this |
| 594 |
+ |
option does not conflict with the bandwidth specified with the |
| 595 |
+ |
.I \-ap |
| 596 |
+ |
option; the number of photons found will not exceed the latter, but may be |
| 597 |
+ |
lower if the maximum search radius contains fewer photons, thus resulting in |
| 598 |
+ |
short lookups. Setting this radius too large, on the other hand, may |
| 599 |
+ |
degrade performance. |
| 600 |
+ |
.TP |
| 601 |
+ |
.BI -ac " pagesize" |
| 602 |
+ |
Set the photon cache page size when using out-of-core photon mapping. The |
| 603 |
+ |
photon cache reduces disk I/O incurred by on-demand loading (paging) of |
| 604 |
+ |
photons, and thus increases performance. This |
| 605 |
+ |
is expressed as a (float) multiple of the density estimate bandwidth |
| 606 |
+ |
specified with |
| 607 |
+ |
.I \-ap |
| 608 |
+ |
under the assumption that photon lookups are local to a cache page. Cache |
| 609 |
+ |
performance is sensitive to this parameter: larger pagesizes will reduce the |
| 610 |
+ |
paging frequency at the expense of higher latency when paging does occur. |
| 611 |
+ |
Sensible values are in the range 4 (default) to 16. |
| 612 |
+ |
.TP |
| 613 |
+ |
.BI -aC " cachesize" |
| 614 |
+ |
Set the total number of photons cached when using out-of-core photon |
| 615 |
+ |
mapping, taking into account the pagesize specified by |
| 616 |
+ |
.I \-ac. |
| 617 |
+ |
Note that this is approximate as the number of cache pages is rounded to |
| 618 |
+ |
the nearest prime. This allows adapting the cache to the available physical |
| 619 |
+ |
memory. In conjunction with the |
| 620 |
+ |
.I \-n |
| 621 |
+ |
option, this is the cache size |
| 622 |
+ |
.I per parallel process. |
| 623 |
+ |
Cache performance is less sensitive to this parameter, |
| 624 |
+ |
and reasonable performance can obtained with as few as 10k photons. The |
| 625 |
+ |
default is 1M. This option recognises multiplier suffixes (k = 1e3, M = |
| 626 |
+ |
1e6), both in upper and lower case. |
| 627 |
+ |
.TP |
| 628 |
|
.BI -me " rext gext bext" |
| 629 |
|
Set the global medium extinction coefficient to the indicated color, |
| 630 |
|
in units of 1/distance (distance in world coordinates). |
| 663 |
|
.TP |
| 664 |
|
.BI -lr \ N |
| 665 |
|
Limit reflections to a maximum of |
| 666 |
< |
.I N. |
| 666 |
> |
.I N, |
| 667 |
> |
if N is a positive integer. |
| 668 |
> |
If |
| 669 |
> |
.I N |
| 670 |
> |
is zero or negative, then Russian roulette is used for ray |
| 671 |
> |
termination, and the |
| 672 |
> |
.I -lw |
| 673 |
> |
setting (below) must be positive. |
| 674 |
> |
If N is a negative integer, then this limits the maximum |
| 675 |
> |
number of reflections even with Russian roulette. |
| 676 |
> |
In scenes with dielectrics and total internal reflection, |
| 677 |
> |
a setting of 0 (no limit) may cause a stack overflow. |
| 678 |
|
.TP |
| 679 |
|
.BI -lw \ frac |
| 680 |
|
Limit the weight of each ray to a minimum of |
| 681 |
|
.I frac. |
| 682 |
< |
During ray-tracing, a record is kept of the final contribution |
| 683 |
< |
a ray would have to the image. |
| 684 |
< |
If it is less then the specified minimum, the ray is not traced. |
| 682 |
> |
During ray-tracing, a record is kept of the estimated contribution |
| 683 |
> |
(weight) a ray would have in the image. |
| 684 |
> |
If this weight is less than the specified minimum and the |
| 685 |
> |
.I -lr |
| 686 |
> |
setting (above) is positive, the ray is not traced. |
| 687 |
> |
Otherwise, Russian roulette is used to |
| 688 |
> |
continue rays with a probability equal to the ray weight |
| 689 |
> |
divided by the given |
| 690 |
> |
.I frac. |
| 691 |
|
.TP |
| 692 |
< |
.BR -ld |
| 692 |
> |
.BR \-ld |
| 693 |
|
Boolean switch to limit ray distance. |
| 694 |
|
If this option is set, then rays will only be traced as far as the |
| 695 |
|
magnitude of each direction vector. |
| 696 |
|
Otherwise, vector magnitude is ignored and rays are traced to infinity. |
| 697 |
|
.TP |
| 698 |
+ |
.BI -cs \ Ns |
| 699 |
+ |
Use |
| 700 |
+ |
.I Ns |
| 701 |
+ |
bands for spectral sampling rather than the default RGB calculation space. |
| 702 |
+ |
The maximum setting is controlled by the compiler macro MAXCSAMP, and |
| 703 |
+ |
defaults to 24. |
| 704 |
+ |
Larger values for Ns will be reduced to MAXCSAMP. |
| 705 |
+ |
.TP |
| 706 |
+ |
.BI -cw " nmA nmB" |
| 707 |
+ |
Set extrema to the given wavelengths for spectral sampling. |
| 708 |
+ |
The default is 380 and 780 nanometers. |
| 709 |
+ |
The order specified does not matter. |
| 710 |
+ |
.TP |
| 711 |
+ |
.BR \-co |
| 712 |
+ |
Boolean switch turns on spectral data output if selected. |
| 713 |
+ |
The default is to reduce spectral results to RGB, but see the related |
| 714 |
+ |
.I \-p* |
| 715 |
+ |
options, below. |
| 716 |
+ |
.TP |
| 717 |
+ |
.BI -pc " xr yr xg yg xb yb xw yw" |
| 718 |
+ |
Use the specified chromaticity pairs for output primaries and white |
| 719 |
+ |
point rather than the standard RGB color space. |
| 720 |
+ |
.TP |
| 721 |
+ |
.BR \-pRGB |
| 722 |
+ |
Output standard RGB values (the default). |
| 723 |
+ |
.TP |
| 724 |
+ |
.BR \-pXYZ |
| 725 |
+ |
Output standard CIE XYZ tristimulus values rather than RGB. |
| 726 |
+ |
.TP |
| 727 |
+ |
.BR \-pY |
| 728 |
+ |
Produce a single output channel corresponding to photopic luminance. |
| 729 |
+ |
.TP |
| 730 |
+ |
.BR \-pS |
| 731 |
+ |
Produce a single output channel corresponding to scotopic luminance. |
| 732 |
+ |
.TP |
| 733 |
+ |
.BR \-pM |
| 734 |
+ |
Produce a single output channel corresponding to melanopic luminance. |
| 735 |
+ |
.TP |
| 736 |
|
.BI -e \ efile |
| 737 |
|
Send error messages and progress reports to |
| 738 |
|
.I efile |
| 786 |
|
on most multiprocessing platforms, since the |
| 787 |
|
.I fork(2) |
| 788 |
|
system call will share memory on a copy-on-write basis. |
| 789 |
+ |
.SH NOTES |
| 790 |
+ |
Photons are generally surface bound (an exception are volume photons), thus |
| 791 |
+ |
the ambient irradiance in photon mapping mode will be biased at positions |
| 792 |
+ |
which do not lie on a surface. |
| 793 |
|
.SH EXAMPLES |
| 794 |
|
To compute radiance values for the rays listed in samples.inp: |
| 795 |
|
.IP "" .2i |
| 796 |
< |
rtrace -ov scene.oct < samples.inp > radiance.out |
| 796 |
> |
rtrace \-ov scene.oct < samples.inp > radiance.out |
| 797 |
|
.PP |
| 798 |
< |
To compute illuminance values at locations selected with the 't' |
| 798 |
> |
To compute irradiance values at locations selected with the 't' |
| 799 |
|
command of |
| 800 |
|
.I ximage(1): |
| 801 |
|
.IP "" .2i |
| 802 |
< |
ximage scene.pic | rtrace -h -x 1 -i scene.oct | rcalc -e '$1=47.4*$1+120*$2+11.6*$3' |
| 802 |
> |
ximage scene.hdr | rtrace \-h \-x 1 \-i scene.oct | rcalc \-e '$1=47.4*$1+120*$2+11.6*$3' |
| 803 |
|
.PP |
| 804 |
|
To record the object identifier corresponding to each pixel in an image: |
| 805 |
|
.IP "" .2i |
| 806 |
< |
vwrays -fd scene.pic | rtrace -fda `vwrays -d scene.pic` -os scene.oct |
| 806 |
> |
vwrays \-fd scene.hdr | rtrace \-fda `vwrays \-d scene.hdr` \-os scene.oct |
| 807 |
|
.PP |
| 808 |
|
To compute an image with an unusual view mapping: |
| 809 |
|
.IP "" .2i |
| 810 |
< |
cnt 640 480 | rcalc -e 'xr:640;yr:480' -f unusual_view.cal | rtrace |
| 811 |
< |
-x 640 -y 480 -fac scene.oct > unusual.pic |
| 810 |
> |
cnt 480 640 | rcalc \-e 'xr:640;yr:480' \-f unusual_view.cal | rtrace |
| 811 |
> |
\-x 640 \-y 480 \-fac scene.oct > unusual.hdr |
| 812 |
> |
.PP |
| 813 |
> |
To compute ambient irradiance in photon mapping mode from a global photon |
| 814 |
> |
map global.pm via one ambient bounce, and from a caustic photon map |
| 815 |
> |
caustic.pm at sensor positions in samples.inp: |
| 816 |
> |
.IP "" .2i |
| 817 |
> |
rtrace -h -ov -ab 1 -ap global.pm 50 -ap caustic.pm 50 scene.oct < |
| 818 |
> |
samples.inp > illum.out |
| 819 |
|
.SH ENVIRONMENT |
| 820 |
|
RAYPATH the directories to check for auxiliary files. |
| 821 |
|
.SH FILES |
| 822 |
< |
/usr/tmp/rtXXXXXX common header information for picture sequence |
| 822 |
> |
/tmp/rtXXXXXX common header information for picture sequence |
| 823 |
|
.SH DIAGNOSTICS |
| 824 |
|
If the program terminates from an input related error, the exit status |
| 825 |
|
will be 1. |
| 833 |
|
.SH AUTHOR |
| 834 |
|
Greg Ward |
| 835 |
|
.SH "SEE ALSO" |
| 836 |
< |
getinfo(1), lookamb(1), oconv(1), pfilt(1), pinterp(1), |
| 837 |
< |
pvalue(1), rpict(1), rview(1), vwrays(1), ximage(1) |
| 836 |
> |
dctimestep(1), getinfo(1), lookamb(1), |
| 837 |
> |
mkpmap(1), oconv(1), pfilt(1), pinterp(1), |
| 838 |
> |
pvalue(1), rcalc(1), rcomb(1), rcontrib(1), rcrop(1), |
| 839 |
> |
rmtxop(1), rsplit(1), |
| 840 |
> |
rpict(1), rtpict(1), rvu(1), vwrays(1), ximage(1) |
