Matthew Corey Brown - XenoArch wrote:

> Due to prescion limitations of Float math, Povray is compiled
> by default with the following:
>
> Anything below 0.001 is considered 0.0
> Anythung beyond +/- 1e7 is non exsistant

Well, pov uses DOUBLEs, and not FLOATs, and the epsilonis 1e-6...
not 1e-3.  I've checked the source.

Besides, I could show you a couple of pictures where a difference
of 0.001 is visible as a thin line.

However, after toying with objects, I've discovered that
the bug is related to spheres and ellipsoids. A cube a couple
of thousand miles wide set at a quarter millon miles is visible
(as a pixel, granted, but still visible). A sphere, 6 k miles wide,
(assuming a pov unit is 1 meter) at 292 000 miles is not visible.

Why?

I have not been able to pinpoint the bug in the source. It
seems OK to me... still, it is not. My guess is that the epsilon
is used in an additive way instead of multiplicative way in
the sphere intersection routine (should be something like
eps * dist rather than just eps).

Best,

     S.

> Don't try to be 100% accurate. Povray isn;t a physics real
> world modeler. its an Artistic Program. As long as it looks
> right to you then its accurate =}



> > 2. Scale your distances to fit within POV's current bounds.  If your moon is 100x
closer and
> >    100x smaller, the error in parellax will be well under one pixel.

That's the best fix, but I dont like it


> >
> > Dan



--
----------------------------------------------------------
Steven Pigeon                     Ph. D. Student.
University of Montreal.
pig### [at] iroumontrealca           Topics: data compression,
pig### [at] jspumontrealca          signal processing,
ste### [at] researchattcom           non stationnary signals
                                  and wavelets.
----------------------------------------------------------
         http://www.iro.umontreal.ca/~pigeon

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