> > And after reading the article at
> > "http://tag.povray.org/povQandT/languageQandT.html#largescaleproblems",
I
> > agree that it's too restrictive... and I was hoping that POV Team could
let
> > the users decide on the restrictions.  Granted faraway objects will not
be
> > accurate.... but... viewing the sun at such a faraway distance, I don't
> > think anyone will notice.
>
> Unfortunantly, the restriction isn't imposed by POV-Ray in and of
> itself.

Well, POV-Ray does make far-away objects invisible on purpose. But as Warp
pointed out, the problems that it's trying to avoid are much worse than,
say, the sphere being sized wrong or slightly off its intended position. The
artifacts tend to be much more ugly: grainy and inconsistent.

 - Slime
 [ http://www.slimeland.com/ ]

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Slime wrote:

> Well, POV-Ray does make far-away objects invisible on purpose. But as Warp
> pointed out, the problems that it's trying to avoid are much worse than,
> say, the sphere being sized wrong or slightly off its intended position. The
> artifacts tend to be much more ugly: grainy and inconsistent.

Maybe I misread..

When did the far away objects being invisible take effect. It used to be 
that POVRay was happy to allow far away objects to render. They were 
difficult (if not impossible) to see, unless you set the camera's angle 
to a rediculously small amount to see said object...

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"Alain" <aze### [at] qwertygov> wrote in message
news:41d5efe6@news.povray.org...

> You hit a hardware limitation, that of the FPU that is "only" 64 bits
> (double presision). To be able to use such whide ranges, you'd need quad
> (128 bits) or octuple (256 bits) presision math, with a processor
> equiped with a FPU capable of such.
> Maybe some super computer have such a beast...

If you want it fast, it's a hardware limitation. Isn't it theoretically
possible to emulate it in software at the cost of speed? (no, i can't offer
examples... just thought it is possible)

if someone really cared, it seems they could probably substitute math
subroutines in povray with a "big math" library.

i had a course on this in college. i forget every word about it, except that
I rendered a scene of the intersection of earth with a fictional comet as
part of a word problem for a  homework assignment. bah

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Michael Raiford <mra### [at] hotmailcom> wrote:
> Slime wrote:
>
> > Well, POV-Ray does make far-away objects invisible on purpose. But as Warp
> > pointed out, the problems that it's trying to avoid are much worse than,
> > say, the sphere being sized wrong or slightly off its intended position. The
> > artifacts tend to be much more ugly: grainy and inconsistent.
>
> Maybe I misread..
>
> When did the far away objects being invisible take effect. It used to be
> that POVRay was happy to allow far away objects to render. They were
> difficult (if not impossible) to see, unless you set the camera's angle
> to a rediculously small amount to see said object...

The sun disappeared about 14.9 million kilometers away.  In realworld, the
sun is 149 million kilometers away, and it's 1.39 million kilometers in
diameter.  The focus is the earth, and the sun is a small disc in the sky.
In realworld, this size and distance should make the sun look as big as the
moon with normal viewing (zoom = 1).

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Ross wrote:
> "Alain" <aze### [at] qwertygov> wrote in message
> news:41d5efe6@news.povray.org...
> 
> 
>>You hit a hardware limitation, that of the FPU that is "only" 64 bits
>>(double presision). To be able to use such whide ranges, you'd need quad
>>(128 bits) or octuple (256 bits) presision math, with a processor
>>equiped with a FPU capable of such.
>>Maybe some super computer have such a beast...
> 
> 
> If you want it fast, it's a hardware limitation. Isn't it theoretically
> possible to emulate it in software at the cost of speed? (no, i can't offer
> examples... just thought it is possible)
> 
> if someone really cared, it seems they could probably substitute math
> subroutines in povray with a "big math" library.
> 
> i had a course on this in college. i forget every word about it, except that
> I rendered a scene of the intersection of earth with a fictional comet as
> part of a word problem for a  homework assignment. bah
> 
It's absolutely possible to have virtualy infinite presision maths. But it get 
sllooooooooooooooowwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww. How do you think they find new,
bilions digits 
long, prime numbers? And why they find them less than once a year using some super
computers full 
time? You have to simulate pen and paper operations using numerous sub results,
calculating each 
digit individualy.

Alain

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