"Kenneth" <kdw### [at] earthlinknet> wrote:
>...in
> experiments I've done, using two simple spheres (one with no_shadow, one
> with no_image) and a single point light just for simplicity, what I see is
> that the final shadow, cast onto a white ground plane, is still quite dark.
> *Almost* black...

I took a more critical look at my own test image, and I have to conclude
that the final shadow isn't "almost black," it IS black. The shadow (from
the no_image sphere) is somehow taking complete precedence. There's no
"brightness mixing" at all. Odd, but interesting. Perhaps that's just the
logical operation of POV's shadow calculations.

Meanwhile, my little test has presented another useful trick, something I've
been pondering for awhile but couldn't figure out how to do, until now:
creating a variable-density shadow. By making the pigment of the no_image
sphere something like rgbt <1,0,0,.5> (the rgb components don't really
matter), its shadow can be made more or less dense/dark. So that an object
that appears to be solid (the no_shadow sphere, in my case) can cast a
variable-darkness shadow.  May not be physically realistic, but could be a
useful artistic tool. Likewise, using rgbf <1,0,0,.5> would cast a reddish,
variable-density shadow.

Ken

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