Warp <war### [at] tagpovrayorg> wrote:

>   The box casts a shadow, which is calculated from the area light
> parameters.

Ah yes. I had neglected to consider that.

>   Whether the objects "see" the light source is determined by the
> shadow calculations, which takes into account area light paramters.
>   Once povray calculates that the object indeed "sees" the light
> source (even if partially) then it calculates the illumination using
> only the point light source part of the light.

That's quite fascinating. So in essence, POV-Ray is performing a sort of
"backwards" calculation when using an area light--the shadow being the
determing factor.
>
>   Btw, as a curiosity: If you are wondering whether it makes any
> considerable difference whether the direct lighting is calculated
> as a point light source or as an area light, the answer is that in
> some scenes it makes a big difference:
>
> http://warp.povusers.org/images/arealight.jpg
> http://warp.povusers.org/images/lightgrid.jpg
>
Thanks for the images.  It does indeed produce a much bigger difference than
I imagined.

Ken

Post a reply to this message