Pattern Design - Cafe Wall Illusion

Hey, my recent pattern design studies brought me to the fascinating world of optical illusions. Here is one of these I reproduced recently to practice procedural material creation in Substance Designer - rendered in Blender to preview how it looks when applied to different surface types.

Cafe illusion - also known as the Münsterberg illusion - is probbaly one of the most known optical illusions. It is a geometrical-optical illusion in which the parallel straight dividing lines between staggered rows with alternating dark and light "bricks" appear to be sloped, not parallel as they really are.

In attempts at its deconstruction, the illusion was ascribed largely to the irradiation illusion (apparent greater size of a white area than of a black one), and the image disappears when black and white are replaced by different colours of the same brightness. But a component of the illusion remains even when all optical and retinal components are factored out. Contrast polarities seem to be the determining factor in the tilt's direction.

A version of the illusion was first described by Hugo Münsterberg in 1894 and has been rediscovered several times, including under the name kindergarten illusion in 1898 by A. H. Pierce, and under its current name in 1973 by Richard Gregory. According to Gregory, this effect was observed by a member of his laboratory, Steve Simpson, in the tiles of the wall of a café at the bottom of St Michael's Hill, Bristol.

In the construction of the illusion often each "brick" is surrounded by a layer of "mortar" intermediate between the dark and light colours of the "bricks".

Cheers!
G.