| 555 |
|
.I \-dv |
| 556 |
|
option (above) may be used to override this. |
| 557 |
|
.TP |
| 558 |
+ |
.BR \-R |
| 559 |
+ |
Boolean switch to control 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 |
