Attached Link: http://www.renderosity.com/viewed.ez?galleryid=131947&Start=1&Artist=Penguinisto&ByArtist=Yes

I've mixed photographs and 3D art before - the linked example uses a grainy 24-bit digital picture taken from an airplane window at sunset... but the blur and grainy aspects make the 'glass' of the Atrium roof more believable, in a way. Also, if the lighting matches the background, things tend to blend in a little more, IMHO. (By the by, I easily admit I'm not perfect at artwork, but I do like the way that oparticular image turned out...)