"Thomas de Groot" <t.d### [at] internlnet> wrote:
> "screwtop" <cme### [at] ihugconz> schreef in bericht
> news:web.440cd3ff38a1658e9f9718b50@news.povray.org...
> > I'm trying to construct some space scenery containing a few very large
> > objects (Sun, Earth, Moon), and a small number of space vessels (~200 m in
> > length).  I started out using a scale of 1 unit = 1 m, but found that
> large
> > objects in the scene disappeared - they simply weren't being rendered.  I
> > switched to 1 unit = 1e6 m, which I thought might be a good compromise,
> > which is better, but the image is very grainy when both large and small
> > objects are rendered in the same scene.  I think these effects must be due
> > to limits of floating-point precision (this is POV-Ray 3.6 on 32-bit
> > Windows XP).  Is there any kind of workaround for this?  I'd really like
> to
> > work to scale if possible.
> >
> > Is the 64-bit version of POV-Ray likely to work better for this kind of
> > scenery? I am using an AMD64 system but currently have no 64-bit Windows
> > installation; IIRC, SSE/SSE2 has 128-bit FP registers.
> >
>
> I am not sure if this will help you, but have a look at this message:
> http://news.povray.org/436572fd%40news.povray.org
> and the few following that (or even the initial discussion). You would need
> version 3.6.0. Can be found on the ftp site of POV-Ray I think, or one of
> the mirror sites.
>
> Thomas

Hello!

I already encountered this kind of problem. I surely comes from POV's
internal epsilons (as shown in the above-mentioned thread). So one must
think of designing scenes with reasonable range for the distances (eg
billion miles away planet/star vs milimetric objects in the foreground)

Perhaps some epsilons could re-adjusted in 3.7 (I don't know much about
POV's internals). In addition, I don't think processor-precision has much
to do with this behaviour compared to these epsilons. Maybe someone more
informed about POV's intimacy could enlighten us. Thanks to him in advance
:)

   Bruno

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