the image fulgurator
So it seems this has been already through all the major blogs I must have missed it. Apparently the image fulgurator is a device that can project images onto anything. The clue is that the images are not visible to the human eye but they do show up on photographs. That allows an (prank)artist to alter often photographed sites and have the tourists wonder what is going on when they snap a picture and the photo looks different then in real life. The fulguration device was developed by Julius von Bismarck from Berlin. How it is constructed can be seen on his site.
The tube video shows the thing in action: