| 89 |
|
.BI -vd " xd yd zd" |
| 90 |
|
Set the view direction vector to |
| 91 |
|
.I "xd yd zd". |
| 92 |
+ |
The length of this vector indicates the focal distance as needed by the |
| 93 |
+ |
.I \-pd |
| 94 |
+ |
option, described below. |
| 95 |
|
.TP |
| 96 |
|
.BI -vu " xd yd zd" |
| 97 |
|
Set the view up vector (vertical direction) to |
| 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 |
| 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" |
| 555 |
|
.I \-dv |
| 556 |
|
option (above) may be used to override this. |
| 557 |
|
.TP |
| 558 |
+ |
.BR \-u |
| 559 |
+ |
Boolean switch to control uncorrelated random sampling. |
| 560 |
+ |
When "off", a low-discrepancy sequence is used, which reduces |
| 561 |
+ |
variance but can result in a brushed appearance in specular highlights. |
| 562 |
+ |
When "on", pure Monte Carlo sampling is used in all calculations. |
| 563 |
+ |
.TP |
| 564 |
|
.BI -lr \ N |
| 565 |
|
Limit reflections to a maximum of |
| 566 |
|
.I N. |
| 567 |
+ |
If |
| 568 |
+ |
.I N |
| 569 |
+ |
is zero, then Russian roulette is used for ray |
| 570 |
+ |
termination, and the |
| 571 |
+ |
.I -lw |
| 572 |
+ |
setting (below) must be positive. |
| 573 |
+ |
If N is a negative integer, then this sets the upper limit |
| 574 |
+ |
of reflections past which Russian roulette will not be used. |
| 575 |
+ |
In scenes with dielectrics and total internal reflection, |
| 576 |
+ |
a setting of 0 (no limit) may cause a stack overflow. |
| 577 |
|
.TP |
| 578 |
|
.BI -lw \ frac |
| 579 |
|
Limit the weight of each ray to a minimum of |
| 580 |
|
.I frac. |
| 581 |
< |
During ray-tracing, a record is kept of the final contribution |
| 582 |
< |
a ray would have to the image. |
| 583 |
< |
If it is less then the specified minimum, the ray is not traced. |
| 581 |
> |
During ray-tracing, a record is kept of the estimated contribution |
| 582 |
> |
(weight) a ray would have in the image. |
| 583 |
> |
If this weight is less than the specified minimum and the |
| 584 |
> |
.I -lr |
| 585 |
> |
setting (above) is positive, the ray is not traced. |
| 586 |
> |
Otherwise, Russian roulette is used to |
| 587 |
> |
continue rays with a probability equal to the ray weight |
| 588 |
> |
divided by the given |
| 589 |
> |
.I frac. |
| 590 |
|
.TP |
| 591 |
|
.BI -S \ seqstart |
| 592 |
|
Instead of generating a single picture based only on the view |
| 794 |
|
.SH ENVIRONMENT |
| 795 |
|
RAYPATH the directories to check for auxiliary files. |
| 796 |
|
.SH FILES |
| 797 |
< |
/usr/tmp/rtXXXXXX common header information for picture sequence |
| 797 |
> |
/tmp/rtXXXXXX common header information for picture sequence |
| 798 |
|
.br |
| 799 |
|
rfXXXXXX temporary name for recover file |
| 800 |
|
.SH DIAGNOSTICS |
