Paradoxical Arrow of Kokichi Sugihara
The Japanese mathematican Kokichi Sugihara has developed this 3D Arrow model: You can can get some idea of what's going on here when he picks it up and shows it from above: ScienceAlert Article on Kokichi Sugihara: This 3D Optical Illusion Will Make You Question The Shape of Reality More 3D Illusions by Kokichi Sugihara: ScienceAlert: Ambiguous Cylinder Illusion Many other fascinating illusions can be viewed at the... Best Illusions of the Year Website Creative Sam's Video of the 7 Best Optical Illusions of All Time... Including the Train Illusion which is somewhat like the dancer that spins two ways...