Shadow Art

For a non-point source of light, the shadow is divided into the umbra and penumbra. The wider the light source, the more blurred the shadow. If two penumbras overlap, the shadows appear to attract and merge. This is known as the Shadow Blister Effect.
If there are multiple light sources there are multiple shadows, with overlapping parts darker, or a combination of colors. For a person or object touching the surface, like a person standing on the ground, or a pole in the ground, these converge at the point of touch.