alphaQuad nous apporta ses lumieres en ce 2007/12/09 22:58:
> Not Shiny
> 
> Wow, Bill's experience really shows in 1st image of this thread.
> 
> Interested in the soft shadows, I attempt duplication.
> I believe this was not Bill's method for the reflection in the apparent chrome.
> 
> #declare cb_=rgb<200,200,217>/255;
> light_source {<10,10,0> color cb_*.4
> #if (10)
>     area_light z*20,y*20, 4,4 adaptive 1 jitter orient
> #end
> }
Adaptive is almost useless with that area_light. Try with this one:
light_source{<10,10,0>color cb_*.4
	area_light z*20,y*20 17,17 adaptive jitter orient circular
}
And compare rendering times.
> light_source {<0,10,-10> color cb_*.4
> #if (10)
>     area_light x*20,y*20, 4,4 adaptive 1 jitter orient
> #end
> }
> #declare cb=rgb<200,200,200>/255;
> light_source {<0,50,0> color cb*.5
> #if (10)
>     area_light x*20,z*20, 4,4 adaptive 1 jitter orient
> #end
> }
> 
> only minutes to render, then AA: 2 hours for this small image
Your textures are very grainy. The floor is grainy, the knot is very grainy, 
your "soft" shadow is very grainy. Consequantly, most pixels need aa.
Scaling up will stretch the grains, reducing the contrast between adjacent 
pixels, resulting in less use of the aa procedure.
> 
> I think Bill's entire scene would be most educational.
> 
> I see no reference to felt, fuzzy or furry.
> (Exception: 3.5.12.6.4  Turbulence Warp octaves (fuzzy))
> Sure looks like a gray felt platform to me.
> 
> Floor ambient 0.1, real low;
> for the theory that it would
> allow visibility of the effect of area lighting
> 
> 
> 
> 
> 
> 
> ------------------------------------------------------------------------
> 
Your area_light array is to sparse, giving you those grainy penumbraes.
The optimum adaptive arrays are: 5*5, 9*9, 17*17, 33*33, 65*65,... This is due 
in the maner that the adaptive process works. The formulae for the optimum array 
size is: 2^n +1 where "n" is at least 1 more than the adaptive value.
As the surface that receive the shadow is close to the object, you can probably 
use adaptive 0 without problem.
With adaptive 0, I regularly use arrays of 17*17 or 33*33 with render times only 
slightly longer than with point lights.

-- 
Alain
-------------------------------------------------
EVERYTHING HAS A GENDER

You may not know this but many nonliving things have a gender...

An Hourglass is Female, because over time, the weight shifts to the bottom.

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