Layered shadow: multiplexing invisible shadow using infrared lights with different wavelengths

This paper proposes a multiplexing invisible shadow system named "Layered Shadow." The proposed system uses infrared lights, each of which radiates a certain wavelength of infrared light, and an object to which two different types of IR filters are attached. Directing the light toward the object causes the object's shadow to appear; the shape of the object then appears to change according to the wavelength of the radiated infrared light. With this system, a user is expected to attain a different viewpoint on shadows.