| 87 |
|
.IP |
| 88 |
|
v value (radiance) |
| 89 |
|
.IP |
| 90 |
+ |
V contribution (radiance) |
| 91 |
+ |
.IP |
| 92 |
|
w weight |
| 93 |
|
.IP |
| 94 |
< |
W contribution |
| 94 |
> |
W color coefficient |
| 95 |
|
.IP |
| 96 |
|
l effective length of ray |
| 97 |
|
.IP |
| 111 |
|
.IP |
| 112 |
|
M material name |
| 113 |
|
.IP |
| 114 |
< |
- dash (end of trace marker) |
| 114 |
> |
~ tilde (end of trace marker) |
| 115 |
|
.IP |
| 116 |
|
If the letter 't' appears in |
| 117 |
|
.I spec, |
| 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 dash marker ('-') is a handy way of differentiating the final ray |
| 124 |
< |
value from traced values preceeding it, and should appear immediately |
| 125 |
< |
after the |
| 124 |
< |
.I \-o |
| 125 |
< |
and before the rest of the specification. |
| 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 \-o-vTmW |
| 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 |
| 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 |
| 230 |
|
.I \-f |
| 231 |
|
option, above.) |
| 232 |
|
.TP |
| 233 |
+ |
.BI -n \ nproc |
| 234 |
+ |
Execute in parallel on |
| 235 |
+ |
.I nproc |
| 236 |
+ |
local processes. |
| 237 |
+ |
This option is incompatible with the |
| 238 |
+ |
.I \-P |
| 239 |
+ |
and |
| 240 |
+ |
.I \-PP, |
| 241 |
+ |
options. |
| 242 |
+ |
Multiple processes also do not work properly with ray tree output |
| 243 |
+ |
using any of the |
| 244 |
+ |
.I \-o*t* |
| 245 |
+ |
options. |
| 246 |
+ |
There is no benefit from specifying more processes than there are |
| 247 |
+ |
cores available on the system or the |
| 248 |
+ |
.I \-x |
| 249 |
+ |
setting, which forces a wait at each flush. |
| 250 |
+ |
.TP |
| 251 |
|
.BI -dj \ frac |
| 252 |
|
Set the direct jittering to |
| 253 |
|
.I frac. |
| 544 |
|
.BI -lr \ N |
| 545 |
|
Limit reflections to a maximum of |
| 546 |
|
.I N. |
| 547 |
+ |
If |
| 548 |
+ |
.I N |
| 549 |
+ |
is zero or negative, then Russian roulette is used for ray |
| 550 |
+ |
termination, and the |
| 551 |
+ |
.I -lw |
| 552 |
+ |
setting (below) must be positive. |
| 553 |
+ |
If N is a negative integer, then this sets the upper limit |
| 554 |
+ |
of reflections past which Russian roulette will not be used. |
| 555 |
+ |
In scenes with dielectrics and total internal reflection, |
| 556 |
+ |
a setting of 0 (no limit) may cause a stack overflow. |
| 557 |
|
.TP |
| 558 |
|
.BI -lw \ frac |
| 559 |
|
Limit the weight of each ray to a minimum of |
| 560 |
|
.I frac. |
| 561 |
< |
During ray-tracing, a record is kept of the final contribution |
| 562 |
< |
a ray would have to the image. |
| 563 |
< |
If it is less then the specified minimum, the ray is not traced. |
| 561 |
> |
During ray-tracing, a record is kept of the estimated contribution |
| 562 |
> |
(weight) a ray would have in the image. |
| 563 |
> |
If this weight is less than the specified minimum and the |
| 564 |
> |
.I -lr |
| 565 |
> |
setting (above) is positive, the ray is not traced. |
| 566 |
> |
Otherwise, Russian roulette is used to |
| 567 |
> |
continue rays with a probability equal to the ray weight |
| 568 |
> |
divided by the given |
| 569 |
> |
.I frac. |
| 570 |
|
.TP |
| 571 |
|
.BR -ld |
| 572 |
|
Boolean switch to limit ray distance. |
| 630 |
|
.SH EXAMPLES |
| 631 |
|
To compute radiance values for the rays listed in samples.inp: |
| 632 |
|
.IP "" .2i |
| 633 |
< |
rtrace -ov scene.oct < samples.inp > radiance.out |
| 633 |
> |
rtrace \-ov scene.oct < samples.inp > radiance.out |
| 634 |
|
.PP |
| 635 |
|
To compute illuminance values at locations selected with the 't' |
| 636 |
|
command of |
| 637 |
|
.I ximage(1): |
| 638 |
|
.IP "" .2i |
| 639 |
< |
ximage scene.pic | rtrace -h -x 1 -i scene.oct | rcalc -e '$1=47.4*$1+120*$2+11.6*$3' |
| 639 |
> |
ximage scene.hdr | rtrace \-h \-x 1 \-i scene.oct | rcalc \-e '$1=47.4*$1+120*$2+11.6*$3' |
| 640 |
|
.PP |
| 641 |
|
To record the object identifier corresponding to each pixel in an image: |
| 642 |
|
.IP "" .2i |
| 643 |
< |
vwrays -fd scene.pic | rtrace -fda `vwrays -d scene.pic` -os scene.oct |
| 643 |
> |
vwrays \-fd scene.hdr | rtrace \-fda `vwrays \-d scene.hdr` \-os scene.oct |
| 644 |
|
.PP |
| 645 |
|
To compute an image with an unusual view mapping: |
| 646 |
|
.IP "" .2i |
| 647 |
< |
cnt 640 480 | rcalc -e 'xr:640;yr:480' -f unusual_view.cal | rtrace |
| 648 |
< |
-x 640 -y 480 -fac scene.oct > unusual.pic |
| 647 |
> |
cnt 480 640 | rcalc \-e 'xr:640;yr:480' \-f unusual_view.cal | rtrace |
| 648 |
> |
\-x 640 \-y 480 \-fac scene.oct > unusual.hdr |
| 649 |
|
.SH ENVIRONMENT |
| 650 |
|
RAYPATH the directories to check for auxiliary files. |
| 651 |
|
.SH FILES |
| 664 |
|
Greg Ward |
| 665 |
|
.SH "SEE ALSO" |
| 666 |
|
getinfo(1), lookamb(1), oconv(1), pfilt(1), pinterp(1), |
| 667 |
< |
pvalue(1), rpict(1), rvu(1), vwrays(1), ximage(1) |
| 667 |
> |
pvalue(1), rpict(1), rtcontrib(1), rvu(1), vwrays(1), ximage(1) |
