Circular-Parade Illusion Created by Half-Body Objects and Mirrors

Abstract

This paper presents a new visual phenomenon in which the shape of a whole animal is created by optical illusion when a physical 3D object representing a head half or a tail half is placed in contact with a mirror, and the resulting whole animal makes a U-turn in another mirror that is perpendicular to the first mirror. Using two such half-body objects, we can create a circular parade of four animals that orient clockwise or counterclockwise uniformly. The mathematics and design principles of this phenomenon are shown with examples. Some extensions are also discussed.