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First Prize of the Best Illusion of the Year Contest 2020 "3D Schroeder Staircase"

My illusion "3D Schroeder Staircase" won the 1st Prize at the Best Illusion of the Year Contest 2020. This object is an example of my experimental material to investigate the behavior of the brains, which are apt to misperceive 2D pictures as 3D objects when they are embedded in real 3D structures. The Schroeder Staircase, which is known as an ambiguous picture for more than 150 years, is decorated by real 3D side walls and support columns. As the result, we perceive new ambiguity, which is different from that of the original Schroeder Staircase.

Oricinal "Schroeder Staircase"

@ The left picture is an ambiguous picture called the "Schroeder Staircase." It has two interpretations, a staircase seen from above and that seen from below, and the second interpretation can be perceived easily if we turn the picture upside-down. This picture was proposed by a German scientist, Heinrich G. F. Schroeder in 1858.

3D Counterpart of the Schroeder Staircase

@ The present 3D object consists of the original Schroeder Staircase picture and real 3D side walls and support columns. It also has two interpretation, both of which are staircases seen from above and switch from one to the other when we rotate the object by 180 degrees around the vertical axis. The second interpretation can also be perceived if we reflect the object by a mirror placed behind the object.

Constructin Kit of the 3D Schroeder Staircase


The diagram of unfolded surfaces of the object is posted here. Please use it for nonprofit purpose only.
Note that the staircase part is a flat picture; it should not be folded.