Le 2022-06-04 à 07:20, Bald Eagle a écrit :
> "HackerDaGreat57" <Hac### [at] gmailcom> wrote:
>> I'm pretty new to POV-Ray and have gotten somewhat experienced with its
>> coordinate system and how it places cameras.
>>
>> I'm wondering what is the limit for coordinates? Take Blender, for example - it
>> starts losing precision after a few thousand meters, but what about POV-Ray?
>>
>> TL;DR: What is the max reliable coordinate number in POV-Ray
> 
> Well, I've never actually pushed that envelope that far, and in that manner.
> 
> But I would imagine that if we're using a source code version based on 32-bit,
> then it would be inherently limited by:
> 
> The range of a 32-bit integer is from -2.14 billion to +2.14 billion, which is a
> range of 4.28 billion, which is 232nd.
> 
> 
> I usually try to limit my numbers to 1 x 10 ^ (+/-) 6 if at all possible.
> 
>
https://news.povray.org/povray.bugreports/thread/%3Cweb.5e9b0b9165bf5d0b5e8f98ff0%40news.povray.org%3E/
> 
> I'm sure Bill Pokorny and others have delved into the gory details of this and
> have a much more accurate sense of min/max.  I think that usually people run
> into the most problems with the small numbers, because there are several
> different places in the code, which may use different cutoff values.
> 
> If your values are too large, then your objects may simply disappear.
> 
> If you're doing a static scene, you may just want to use a scaling factor that
> brings everything into a nice, manageable range of values.
> 
> If you're doing an animation, you might want to think about constructing your
> scene such that your camera is at or close to the origin, and everything else is
> defined in relation to that.  You may also want to consider implementing some
> form of proximity and Level-Of-Detail scheme to detrmine if things are close
> enough to the camera to even bother instantiating, and how the geometry and
> texturing should be implemented.   There's no reason to use an image-map on an
> isosurface object that's so far away that it will only be seen as a
> color-averaged, antialiased 4 pixel blob....  render it as a simple pigmented
> sphere instead.
> 
> - Bill
> 

POV-Ray use double precision floats, not integer.
The real issue is the range of values between the smallest object and 
the longest distance in the scene.

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