> Le_Forgeron <jgr### [at] freefr> wrote:
>
>> What is GI, AO ?
>>
>> About soft shadow... if it's a point of light, it cannot be soft.-
>>
>> Or you have a definition of point that is no more a point.
>>
>> Area lights have many optimisation (such as adaptative) which can be
>> used to have real large array without the cost of as many point lights.
>>
>> jitter, orient & circular are cool too.
>>
>> http://www.povray.org/documentation/3.7.0/r3_4.html#r3_4_4_1_5
>>
>> Maybe wanting something like the fading cone of spot light ?
>
> GI = Indirect Lighting (Like Radiosity), AO is a fast method of faking shadows
> in crevices, which helps enormously when faking indirect lighting to speed up
> renders.
>
> Also you can have soft shadows with point lights (or in fact any light), many
> other render engines do it. You just have to trace a bunch of shadow rays up
> towards the light rather than just one, and give them a semi-random offset
> between the direction of the light and a user defined maximum (which defines how
> soft the shadow is). The more rays you trace the cleaner it will be.
>
>

Does AO mean ambient oclusion? If that's the case, it's only a tiny 
subset of radiosity. It lack the ability to take into account the colour 
and reflectivity of the ocluding object: it may be black or white and 
cause exactly the same darkening.

NO, it's absolutely impossible to have any kind of soft shadow from a 
point light. Other renderers may /fake/ soft shadows, like you can 
/fake/ focal blur, in a non-realistic way.
The mechanism that you mention is faking it. It's probably no faster, 
nor beter, than using an area_light in POV-Ray.

Just use a light source, add area_light, the dimentions of the area, and 
the number of sub-lights. Greatly improve the performances by using 
adaptive. Great controll, good performance.
The larger the number of sub-lights, the cleaner the result. Make the 
dimention larger to get broader penumbrae.


Alain

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