Into the Pit
This is a chalk drawing on the sidewalk, by Belgian artist Julian Beever, passed along through email from Owen Western. Owen then manipulated the photo to show what it actually looks like seen from above (see secondary image).

Not stereo images, but these anamorphic chalk drawings are essentially 2-dimensional phantograms. Or put another way, a phantogram is a stereo anamorphosis; this is a regular anamorphosis.