thanks firstly,

i construct the mesh with marching cube algorithm based on a regular grid,
and the resolution of my grid is 80X40X100.

i check the online help of pov-ray, and it says: Typically values whose
absolute values are less than a preset value epsilon are considered false
for logical expressions. The value of epsilon is system dependent but is
generally about 1.0e-10. Two floats a and b are considered to be equal if
abs(a-b) < epsilon.

so maybe i should save my mesh file with double type, am going to try it,:)


"Tim Nikias" <JUSTTHELOWERCASE:timISNOTnikias(at)gmx.netWARE> wrote:
> > Could be very well, though, that your problem has a completely different
> >    source.
>
> Another trouble could be that the normals don't point to the same side of
> the triangle. I recall lighting issues when some of the normals of the
> triangle were calculated clockwise and some counterclockwise when generating
> them using my MMM with a faulty code.
>
> Additionally, what's the size of your triangles? If they're *very* tiny, you
> could run into the floating-point precision problem.
>
> Regards,
> Tim
>
> --
> aka "Tim Nikias v2.0"
> Homepage: <http://www.nolights.de>

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