Hugo wrote:
>
> > The fade_power doesn't depend on the measuring of distance.
> 
> I don't understand that.

intensity = 2/( 1 + (d/fade_distance)^fade_power )

At the surface the intensity is 2 and at fade_distance the intensity
is 1. It's a continous smooth function. Take a scene and scale it by
10 but don't modify fade_power. You will see that fade_power doesn't
depend on the measuring of distance. 1/d^2 for intensity holds true
for point sources in RL, why not in povray.

The more complicated equation in povray simulates how light sources
with non-zero dimensions behave at close range. It's the result of
integrating multiple point sources over an area, I believe. When d
is large enough the equation simplifies to 1/d^2 (in a broad sense).

I verified that this equation works for planar diffuse sources:
http://news.povray.org/povray.binaries.images/19212/
I assumed of course, that povray radiosity works :)


_____________
Kari Kivisalo

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