These girls couldn't wait for the completion of the piece before having fun with it (they literally couldn't wait, as their camp was over and they had to catch the next bus down the mountain and back to Osaka or some other metropolitan location away from the more natural mystique of Nagano). Still, the image was a point that the illusion works, and I admire that they were so ready to use it. I guess you could call this a "process" image.