Kenneth <kdw### [at] earthlinknet> wrote:
> The word "object" here is somewhat ambiguous.

  Yes. "Surface" would be much better.

> In one or several places in
> the documentation, a light source, in general, is referred to as an object
> (like any other object.) But in this context, I read it to mean the object
> BEING illuminated by the light...although I'm not sure about that. Either
> way, I'm a bit confused about this description of an area light being just
> a "point source."

  As the documentation says, the area light parameters are taken into
account only when calculating shadows. When calculating direct illumination
they are ignored (which means that in direct illumination it's just a
point light source, like everything you wrote in the light source related
to area lights was removed).

  (And no, this is not necessarily a good thing. It is just implemented like
that currently.)

> To better illustrate what I'm talking about: If I purposely place a typical
> object like a box at the location of the area light, but offset the box
> slightly, it appears to occlude part of the area light's illumination on
> other objects in the scene. (The overall light gets "grainy" or spotty.)
> Which leads me to conclude that the box is blocking some of the area light
> array. And that it does occupy a certain spatial dimension, not just a
> point.

  The box casts a shadow, which is calculated from the area light
parameters. Naturally if you want the shadow to be any good, with
the box being so close to the light source, you'll have to make the
area light quite dense and use a high 'adaptive' value (or not use
it all, which will naturally make the whole rendering quite slower).

> Or does the documentation actually mean, in a literal way, that the
> illumination from the area light emanates from just ONE point--as far as
> the objects being illuminated are concerned? In other words, do the
> illuminated objects in the scene "see" the area light as just a single
> point?

  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.

  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

-- 
                                                          - Warp

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