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"Cousin Ricky" <rickysttATyahooDOTcom> wrote:
> "Bruno Cabasson" <bru### [at] cabasson com> wrote:
> > Hi all!
> >
> > Considering that many 3D applications (eg games) use single precision for their
> > renders, I am wondering where we really need double precision for 'normally'
> > sized scenes. I mean scenes that do not mix microscopic and gigantic distances.
> >
> > For sure, if the dynamic is huge, we absolutely need double precision, at least
> > for object coordinates. But, if the dynamic in distances is reasonable, is it
> > mandatory to use double precision for the following features :
> >
> > ray - bounding box intersection tests ?
> > ray - object intersection computation ?
> > others (TBD) ?
> >
> [snip]
> >
> > What do you think ? Has the subject already been debated here ?
>
> The dynamic doesn't even have to be huge. See:
>
>
http://news.povray.org/povray.binaries.images/thread/%3Cweb.47e40ce72d3a644685de7b680@news.povray.org%3E/?ttop=304745
&t
> off=500
>
> Since the error was not lighting-related, I don't think the 37,417 POV-unit
> distance to the light source should be considered in the dynamic. What sort of
> dynamic do you have in mind?
>
> POV-Ray does not seem suited to single precision. Perhaps it is the nature of
> mathematically defined shapes that they require higher precision than mesh-based
> systems.
Meshes also involve maths ...
The kind of dynamic I have in mind could be a 1 millimeter detail close to the
camera, and a million miles away huge object. Take the recent post with the
toroidal planet in pbi. Imagin the camera sees a flower on its ground with small
petals.
My question was about the fundamental need of double precision in Ray-Tracing
for 'normal' scenes. What features need DP, and what need not.
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