Bruno Cabasson nous apporta ses lumieres en ce 11/09/2006 05:28:
> "Cousin Ricky" <ric### [at] yahoocom> wrote:
>> "Bruno Cabasson" <bru### [at] alcatelaleniaspacefr> wrote:
>>> I have one concern with this result: the shadow of the shape on the ground
>>> does not seem to be anti-aliased. What's up?
>> It's two things.
>>
>> 1. The threshold *is* too high.  Set Antialias_Threshold to 0.02, or use
>> +A0.02.  (Most scenes won't need it this low, but this scene does.)  I also
>> figured out the reason why the glass seemed antialiased but not the shadow:
>> the dispersion!  As the light spread out inside the glass, it automatically
>> fudged the aliasing artifacts.
>>
>> 2. Ooh, i almost forgot.  Use +AM2.  Never mind that, just add
>> Sampling_Method=2 to your povray.ini file and be done with it.
> 
> OK. After following these advises, I found that the aa threshold is
> responsible for the (apparent) non anti-aliasing. I was persuaded that the
> 'constrast' between the shadow and the ground was OK for 0.3. The value 0.1
> is enough. +AM2 is not necessary.
> 
> Another concern now: when I turn photons off by commenting out the photons{}
> block in global_settings{} the shadow has a green color, which may seem
> normal because the material is green (see picture). Why then, when photons
> are on, does the shadow not inherit the green color of the glass?
> 
>     Regards
> 
> 
> ------------------------------------------------------------------------
> 
Without photons, the shadow ignore the ior of the object, so the shadow is 
completely illuminated by the filtered light. It's a little like the onject was 
only a coloured empty shell. This is unrealistic.
With photons, the light don't reatch the shadowed area, only the photons do. 
It's what apens in the real world, and what you would see if you where outside 
on the moon: a totaly dark shadow only illuminated by the diffracted light.

-- 
Alain
-------------------------------------------------
Documentation; The worst part of programming.

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