I think our difference now simply boils down to semantics. I define spatial information less narrowly. Any information in a photograph (perspective for example) which provides some clues that allow one to make an informed estimate (guess) about the relative position and/or size of the 3D objects, I would describe as spatial information. Clearly it is not always guaranteed to be correct information, and certainly one can have photos which contain no spatial information (even by this looser definition).
Yes, agree. And thats why in my first post wrote "The information can be used to guess about spatial, but no information can be derived for sure. Its no way of knowing the relative spatial positions to objects in a photo, or even if they are spatial." So I would have said "information to create spatial models" instead of "spatial information". But again, this might be to formal. It boils down to as you say semantics.
This is in agreement with what bill t., BJL, Ellis Vener, Hjulenissen, yourself and perhaps others have said here. Thanks to all.
I have always loved fishing. As a very young boy I learned a trick when being photographed with my catch. Hold the fish at arms length straight out in front of my body, and close to the camera. At first glance it makes the fish look much bigger, but it doesn't fool too many viewers. Which brings us back to the original theme of this thread. It is this same "trick" that makes a nose look much bigger in proportion to the face when the camera is positioned quite close.
Totally OT, but you should look my site
http://flyalf.com/. On the right hand side there are links to some of my fishing trips

.
Check out this

(no, not myself in the pic):
http://www.flickr.com/photos/25078442@N05/4922442239/in/set-72157624795885356