I've got an odd situation:

I posted three images to p.b.i that will hopefully illustrate my problem.  I
have a simple scene cosisting of two cones and a sphere.  One cone is used
as a base texture, while the other is an image map (with a filtered color to
allow the underlying texture to show through).  The image mapped cone is
slightly larger than the base cone, to avoid any coincident surface
problems.

Now, if I render the scene with a point light source, and all three objects
are present, it looks as I would expect (first picture - the two cones are
indistinguishable, as the filtered image map blends into the base texture).
However, if I switch to an area light source, OR remove the sphere (or
both), then suddently my base cone becomes dark, and only the filtered color
on the image map appears correct (second and third picture - shows the image
map and surrounding filtered area just as in the first example, but the base
cone is much darker, making it obvious where the image map lies).

I've no idea why this is the case.  I played with the area light, and
reduced it to a 1x1 source (which should look identical to a point source,
correct?) and the strange difference is still apparent.  I can also change
the sphere to other objects at other positions, and as long as something
besides the two cones is present and I use a simple point source for the
light, the image will render correctly (well, MY idea of correctly).

Anyone wish to explain this?  I'm apparently not so good with image maps...

- How

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