If one projects a MONDRIAAN painting on the wall, and use a computer to generate the depth lines according to the position of the viewer (tracked by a sensor), a virtual depth will be visible. The depth lines change with the position of the viewer in a correct way. At the same time the same image is projected simultaneously at the opposite wall. If the viewer turns around he will experience the same painting but with the wrong depth impression. As he moves, the depth lines will change in a unnatural way. See www.baltanlaboratories.org for more information.