Perspective can influence perception

Things like this fascinate me.  It reminds me that you and I don't see or understand things in the same way, even when we look at what we assume is the "same thing."  Your life experiences and mine are so different that we have different perspectives, of necessity.  You assure me what you see is a square, and I insist it's spherical — or at least round.  Hmm, I've even started opposing my own argument.

From the camera's angle, we could even assert that there's a diamond in the blue light and an oval in the yellow light.  To add to the confusion, I want to know why the dark circle on the right is solid — since the object making the shadow seems hollow to me, like a rolled-up piece of paper taped together.  Why isn't the shadow ring-shaped, with light flowing brightly through the middle?