Nope, translations can have an effect - at least I ran into similiar
problems just moving the camera slightly. In one position a simple sphere
iso rendered without problems, moved the camera and someone had been
munching on it.

Sorry, I would have suggested this before, but I misread your original
posting and thought you were saying that you were having odd results that
were corrected by just re-typing the same co-ords.

"Marc-Hendrik Bremer" <Mar### [at] t-onlinede> wrote in message
news:395c9194@news.povray.org...
> Thanks for the link to the tutorial, but I think that is another case. I
> know those holes in Isosurfaces and yes sometimes they even disappear.
> But I did not change anything in the Isosurface settings, but I translated
> it only one tenth of a pov unit upward. In my case the same scene source
> produces to different pictures - first, one isosurface misses, the second
> time it doesn't. With this max_gradient-problem, the surface will always
be
> the same?
>
> Marc-Hendrik
>
>
> Gilles Tran schrieb in Nachricht <395C8D22.35D9BE2B@inapg.inra.fr>...
> >Marc-Hendrik Bremer wrote:
> >
> >> I wonder, if others have experienced the same: Sometimes, when I just
> change
> >> my positioning in a scene a little bit (changed a "translate") and
render
> it
> >> with megapov, one isosurface occasionally disappears.
> >
> >Possibly a max_gradient related problem.
> >The usual solution is to look for the right max_gradient in the stats (it
> >appears when using the "eval" keyword) and write it in the isosurface
> >definition.
> >Have a look at Mike Williams' tutorial here for a better explanation :
> >http://www.econym.demon.co.uk/isotut/keywords.htm
> >
> >G.
> >
>

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