"Bruno Cabasson" <bru### [at] alcatelaleniaspacefr> wrote:
> Alain <aze### [at] qwertyorg> wrote:

> > > clipka<ano### [at] anonymousorg>  wrote:
> > >> Am 11.02.2011 09:43, schrieb Bruno Cabasson:
> > >>> Lots of photons here ....
> > >>
> > >> High dispersion count, too, I guess...
> > >>
> > >> Looks awesome!
> > >
> > >
> > > ior = 1.5
> > > dispersion = 1.1
> > > dispersion_count = 768
> > > gather_min = 128
> > > gather_max = 512
> > >
> > > 127+ million photons (highly diluted far from lenses...)
> > >
> > > I could not get rid of the interference fringes, probably due to spiral pattern
> > > of the shooting. The solution could consist in making them sub-pixel, but this
> > > means also lower resolution for a smooth result, or even more photons! Another
> > > shooting method could avoid these fringes.
> > >
> > > The actual diameter of the incoming beam (cylindrical light_source) is smaller
> > > than the one rendered, and corresponds roughly to the center part of it. Due to
> > > gathering?
> > >
> > > Render time: about 8 hours on a dual Xeon 3Ghz. I had to mask the prism side
> > > pointing to the camera, otherwise, rays get lost forever inside the prism.
> > >
> > > Bruno.
> > >
> > >
> >
> > Any jitter for the photons? It can greatly help getting rid of those
> > "interference fringes".
> > Another thing that can help is to use more samples for your media. Here
> > also, jittering can help somewhat.
> >
> >
> > Alain
>
> I tried! But the result was always more or less splotchy. The only way I found
> to get a smooth result is to use no jitter. It reduces the number of photons,
> but the jitter pattern appears, mainly in highly diluted areas... It is just an
> experiment.
>
> Bruno

And I forgot: I used

global_settings {
  max_trace_level 15
  photons {count PHOTON_COUNT media PHOTON_MEDIA jitter 0 gather GATHER_MIN,
GATHER_MAX}
}

with PHOTON_MEDIA = 1e6

I think 1e6 is enough.

Bruno

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