Alain <kua### [at] videotronca> wrote:

> > Stephen <mca### [at] aolcom> wrote:
> >> On 21/07/2013 9:37 PM, MichaelJF wrote:
> >>> This will take the one or other day due to the rendering times. I have reviewed
> >>> the two lower levels now. Not completely satisfying but the best compromiss I
> >>> can yield so far. Sometimes a change of 0.01 for the scattering color changes
> >>> the image completely having this strange density maps. I'm not quite sure to
> >>> repair the density of the upper "cloud", may be I change the color to be more
> >>> white. But as Thomas said the lighter parts are blown up into the air and they
> >>> must be more easily be influenced by the wind, which is blowing here from right
> >>> to left, especially at greater altitudes.
> >>
> >>
> >> We have the patience. :-)
> >>
> >> --
> >> Regards
> >>       Stephen
> >
> > Sometimes I'm not quite sure I will have the patience needed. But today I found
> > out the reason of my problems just by chance. I always had ribbon like
> > structures around my "cloud" which were annoying completelly. But they did not
> > come from the df3-file or the scattering or absorbing parameters or the the warp
> > turbulence, I would have expected them. They came from "interpolate 2" within
> > the density file definition. I ever thought that a cubic interpolation would be
> > better than a linear one only resulting in longer rendering time. But seems, I
> > was wrong with that.
> >
> > Best regards,
> > Michael
> >
>
> It's a bug present in version 3.6.x. When you have areas with a value of
> zero, the interpolation cause some areas to evaluate to a negative value
> that warps around to give values that are close to 1. I think that it's
> corrected in version 3.7.
>
> The workaround is to never have any zero in the DF3 file and to adjust
> the colour_map accordingly.
>
> Yet another reason to upgrade to version 3.7 :)
>
>
>
> Alain

Thanks, bur I have forgotten to mention my version. I'm using a machine which is
only some months old and I had never older versions of POV installed on this
one. The only POV installation I had ever at my actual machine is version 3.7 RC
7 (Windows version).

At my Suse laptop I have only 3.6 since I failed to compile the sources due to a
problem with the boost library. It is installed by default but the POV configure
cannot find it even after specifying the path given by yast.

Best regards,
Michael

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