Limited, jcviggen,
Iīm a little bit skeptical about this explanation.
First: the imageīs geometry donīt seems to be in agreement with your thesis of "vanishing of shadows". I think that it would occur if the source of the light were close to the lens (POV). But when you look to the shadows, you see that some objects display two shadows, inclined with respect one another, what probably means that there are two light sources in some distance of each side of the lens. I think this geometry isnīt very probable to cause any "vanishing of shadows" at the designated place of the image...