"Thomas White" <her### [at] removebtinternetcom> wrote in message
news:39f608de@news.povray.org...
>
> I've noticed that bumpiness isn't affecting the overall shape of the sphere,
> but I can definately see a sharp edge to the illumination that isn't there
> when the bumpiness is commented out.  When I reduce to just one light source
> it's made even more clear.
>
> Apologies if I'm just digging myself further into a newbie-pit here but I
> don't understand where the sharp edge is coming from.

I see now what you were actually trying to find out about is why a texture
normal causes the sharp shadow/light boundary on a object.  That I don't know,
I simply live with the fact.  But, I think you are seeing the faked high parts
mostly and perhaps the low parts in the normal aren't as obvious, leaving some
places with a expected terminator (shadow line) and not other parts.  The
surfaces finish makes a difference in how it appears as well, so if a highlight
is on there (esp. with second, third lights) it's all the more noticeable... or
unnoticeable.  Depends.
Anyway, it comes down to the same general thing I first said.  The faked high
spots aren't really higher up than their surroundings and thus only a
undisturbed shadow line shows up.
Once again, MegaPOV can do actual surface perturbations so maybe you'll want to
try it.  Check out isosurface and pigment function (pigment pattern equals any
normal pattern of the same type).

Bob

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