"Burki" <nomail@nomail> wrote:
> Hi!
>
> I agree with Mike:
>
>
> >My guess is that they might possibly be real effects. The particular
> >shape of the superellipsoid causing infinite internal reflections.
>
> When I set
> max_trace_level 10
> color instead if rgbt 1 to 0.96
> and in the ior: fade_power 1001
> then also black dots appear:
>
> Bu.

I just made another try with simplified scene (no carving, no photons, one
single light source), scaling the isosurface <0.6, 1, 0.45> instead of
<0.6, 1, 0.25> and lowered the 'east' and 'north' parameters (curvature
radii of the superellipsoid) down to 0.005 (almost a box), and here is what
I get. Rem: to avoid any undesirable interaction with the ground, the shape
is translated vertically 0.1*y.

The bottom of the stella is dark (adding a sky_sphere makes it look better)
because it reflects the black sky.

With higher values of the radii than my 0.005 (original 0.25 value for
example), the top seems to reflect that darkness and so on. The probem is
that these dark areas are irregular. If they were more regular, I would
think it is a normal and natural effect. So what? Numerical artifacts?

With east=north = 1, we get an ovoid that looks quite OK. With a box, it is
perfect. So, I think the problem comes from the superellisoid function
which maybe implements epsilons or whatsoever that produce those artifacts.

A last try with a sphere, and we have the same aspect than the
superellipsoid with radii=1.0.

My last remark for that post is: in the original scene, it would be cautious
to raise the shape enough along y-axis in order to make sure no point of
the ellipsoid touches the ground because the sides are also curved!

   See you soon

       Bruno

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