[Radiance-general] Reduce rtrace runtime

[Jia Hu]

Hello Greg:

Because there are blinds in the office and the rays are only from the
outside sky (no light source in the office), is your approach still accurate
enough in this case? I am not familiar with this approach. Does your book,
Rendering with Radiance, have some introductions to such options as "lr"
"lw". I checked the last several chapters and did not find "lr" and "lw".
Thanks,
Jia
On Mon, Aug 30, 2010 at 9:55 PM, Greg Ward <gregoryjward at gmail.com> wrote:

> Computing seven bounces (-ab 7) is very expensive, even for a small number
> of points.  You end up filling the indirect irradiance cache, which takes
> some time even on 4 processors.  I would recommend either reducing the
> number of bounces, or taking advantage of a path tracing approach like so:
>
>        rtrace -w -h -I -ab 7 -n 4  -ad 2048 -as 0 -aa 0 -lw 1e-5 -lr -10
> -u+ office.oct < points.inp
>
> Setting -aa 0 and -lw 1e-4 limits the number of paths to roughly 100,000
> per point, which should run pretty quickly while maintaining accuracy.
>
> Best,
> -Greg
>
>
> > From: Jia Hu <hujia06 at gmail.com>
> > Date: August 30, 2010 6:11:21 PM PDT
>  >
> > Hello experts:
> >
> > I hope to calculate illuminance at 4 points in a office under four 100
> sky conditions (each condition will generate four illuminance values). I run
> rtrace in a  computer with 4 processors and use: rtrace -w -h -I -ab 7 -n 4
>  -af cachingFile.ca -ad 2048 -as 512 -aa 0.10 office.oct < points.inp |
> rcalc -e '$1=47.4*$1+ 120*$2+11.6*$3'>> output.out.
> >
> > I tried to run it but it took long time. My question is that whether
> there are ways of improving the rtrace command to reduce the runtime?
> >
> > Cheers,
> > Jia
>
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