Forgot to say, don't criticize the shape or angle of the shadow - you can work that out yourself. I was having trouble matching the degree of blurring with the rest of the scene.

Click to see full size and examine closely the variations in the ball's shadow. It is not a solid color, but rather is showing response to the variations of the real ground image.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)