Hi,

thank you for your really detailed answer. most of the things you mentioned
where already in my code, but you couldn't know of course.

I tried several things, but i must say that controlling the color with fade
color is extraordinarily difficult for me and i didn't get any reasonable
results. also fresnel reflection doesn't give me the feel i wanted although it
might be more in realistic in the physical manner.

i removed the caustics statement from the interior too, and now this dumb spot
has also vanished ;)

again thank you for your efforts :)

regards, peter


Alain <ele### [at] netscapenet> wrote:
> syngola nous illumina en ce 2008-09-12 12:32 -->
> > Hi everyone,
> >
> > i played a little with cutting nested spheres with another one. would like to
> > know what to improve on the texture. i am quite unsure if the lower region of
> > the outer sphere isn't too bright.
> >
> > regards, peter
> >
> >
> > ------------------------------------------------------------------------
> >
> Nice.
> You should note that the hot spot under your hollow nested spheres should NOT be
> there. They are effectively acting as divergent lences. Apparently, you used the
> caustics keyword, remove it and use photons to get a realistic effect.
> Set your spheres in an union, and give it the following:
> photons{target refraction on reflection on}
>
> and add the followint to your global_settings:
> photons{spacing 0.1}//minimal basic photons block
>
> About the finish:
> How much ambient do you have? It looks like it's set to high. It may be better
> with ambient 0, a low difuse, like difuse 0.5 or maybe less. Usualy, glass rely
> on it's interior more than on it's surface for it's colouration and aspect.
>
> Glass, and almost every transparent substances have variable reflection. Low
> value (about 0.1 for glass) when viewed perpendicaly, almost 1 for tangent rays.
> Also set fresnel on.
> Don't forget to set conserve_energy in your finish.
> The pigment can be close to rgbt 1.
> For the interior:
> Rely more on fade_color, fade_distance and fade_power to get your colouration.
> In your case, you'll need a small fade_distance, about 1/2 the thickness of your
> shell. Reduce that value for the inner shells, as well as making the fade_color
> darker.
> Realistic value for the fade_power of tranparent substances are 1 or 1001.
> It look like your glass contains some media. If it does, and it's emissive
> media, change it to scatthering media. Your glass is not supposed to emit light.
>
> --
> Alain
> -------------------------------------------------
> You know you've been raytracing too long when your wife's raytraced image you
> made to flatter her is the only one you see of her anymore.
> Ken Tyler

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