| 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 |
| 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. |
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+ |
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 |
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+ |
specifying: |
| 51 |
+ |
.nf |
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+ |
|
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+ |
rtrace -features FeatName=subfeat1,subfeat2 |
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+ |
|
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+ |
.fi |
| 56 |
+ |
If any named feature or subfeature is missing, an error is |
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+ |
reported and the program returns an error status. |
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+ |
If all of the named features are present, a zero status is returned. |
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+ |
.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. |
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|
In addition to these three choices, the character 'c' may be used |
| 89 |
< |
to denote 4-byte floating point (Radiance) color format |
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< |
for the output of values only |
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< |
.I (\-ov |
| 92 |
< |
option, below). |
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> |
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 |
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|
Note that there is no space between this option and its argument. |
| 131 |
|
.IP |
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|
M material name |
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|
.IP |
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+ |
r mirrored value contribution |
| 135 |
+ |
.IP |
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+ |
x unmirrored value contribution |
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+ |
.IP |
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+ |
R mirrored ray length |
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+ |
.IP |
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+ |
X unmirrored ray length |
| 141 |
+ |
.IP |
| 142 |
|
~ tilde (end of trace marker) |
| 143 |
|
.IP |
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|
If the letter 't' appears in |
| 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. |
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> |
conjunction with ximage(1) for computing irradiance at scene points. |
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|
.TP |
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|
.BR \-u |
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|
Boolean switch to control uncorrelated random sampling. |
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|
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 |
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|
.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. |
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|
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 |
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> |
virtual sources; a value of 2 means that first generation |
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> |
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 |
| 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 |
< |
In photon mapping mode (see |
| 435 |
> |
This value defaults to 1 in photon mapping mode (see |
| 436 |
|
.I -ap |
| 437 |
< |
below), a positive value implies that global photon irradiance is |
| 410 |
< |
always computed via |
| 437 |
> |
below), implying that global photon irradiance is always computed via |
| 438 |
|
.I one |
| 439 |
< |
ambient bounce. A negative value enables a preview mode that directly |
| 440 |
< |
visualises the irradiance from the global photon map without any ambient |
| 441 |
< |
bounces. |
| 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 |
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|
.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 |
| 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. |
| 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 |
| 583 |
|
for debugging and validation of photon emission. |
| 584 |
|
.TP |
| 585 |
|
.BI -am " frac" |
| 586 |
< |
Coefficient for maximum search radius for photon map lookups. The search |
| 587 |
< |
radius is automatically determined based on the average photon distance to the |
| 588 |
< |
distribution's centre of gravity, and scaled by this coefficient. Increase this |
| 589 |
< |
value if multiple warnings about short photon lookups are issued. |
| 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). |
| 671 |
|
termination, and the |
| 672 |
|
.I -lw |
| 673 |
|
setting (below) must be positive. |
| 674 |
< |
If N is a negative integer, then this sets the upper limit |
| 675 |
< |
of reflections past which Russian roulette will be used. |
| 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 |
| 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 spectral |
| 729 |
+ |
sensitivity. |
| 730 |
+ |
.TP |
| 731 |
+ |
.BR \-pS |
| 732 |
+ |
Produce a single output channel corresponding to scotopic spectral |
| 733 |
+ |
sensitivity. |
| 734 |
+ |
.TP |
| 735 |
+ |
.BR \-pM |
| 736 |
+ |
Produce a single output channel corresponding to melanopic spectral |
| 737 |
+ |
sensitivity. |
| 738 |
+ |
.TP |
| 739 |
|
.BI -e \ efile |
| 740 |
|
Send error messages and progress reports to |
| 741 |
|
.I efile |
| 798 |
|
.IP "" .2i |
| 799 |
|
rtrace \-ov scene.oct < samples.inp > radiance.out |
| 800 |
|
.PP |
| 801 |
< |
To compute illuminance values at locations selected with the 't' |
| 801 |
> |
To compute irradiance values at locations selected with the 't' |
| 802 |
|
command of |
| 803 |
|
.I ximage(1): |
| 804 |
|
.IP "" .2i |
| 813 |
|
cnt 480 640 | rcalc \-e 'xr:640;yr:480' \-f unusual_view.cal | rtrace |
| 814 |
|
\-x 640 \-y 480 \-fac scene.oct > unusual.hdr |
| 815 |
|
.PP |
| 816 |
< |
To compute ambient illuminance in photon mapping mode from a global photon |
| 816 |
> |
To compute ambient irradiance in photon mapping mode from a global photon |
| 817 |
|
map global.pm via one ambient bounce, and from a caustic photon map |
| 818 |
|
caustic.pm at sensor positions in samples.inp: |
| 819 |
|
.IP "" .2i |
| 837 |
|
Greg Ward |
| 838 |
|
.SH "SEE ALSO" |
| 839 |
|
getinfo(1), lookamb(1), mkpmap(1), oconv(1), pfilt(1), pinterp(1), |
| 840 |
< |
pvalue(1), rpict(1), rcontrib(1), rvu(1), vwrays(1), ximage(1) |
| 840 |
> |
pvalue(1), rcontrib(1), rsplit(1), |
| 841 |
> |
rpict(1), rtpict(1), rvu(1), vwrays(1), ximage(1) |
