An impossible object is a type of optical illusion. It consists of a two-dimensional figure that is instantly and subconsciously interpreted by the visual system as representing a projection of a three-dimensional object.

In most cases the impossibility becomes apparent after viewing the figure for a few seconds. However, the initial impression of a 3D object remains even after it has been contradicted. There are also more subtle examples of impossible objects where the impossibility does not become apparent spontaneously and it is necessary to consciously examine the geometry of the implied object to determine that it is impossible.

The unsettling nature of impossible objects occurs because of our natural tendency to interpret 2D drawings as 3D objects. With an impossible object, looking at different parts of the object makes one reassess the 3D nature of the object, which confuses the mind.

Although possible to represent in two dimensions, it is not geometrically possible for such an object to exist in the physical world. However, some models of impossible objects have been constructed, such that when they are viewed from a very specific point, the illusion is maintained. Rotating the object or changing the viewpoint breaks the illusion, and therefore many of these models rely on forced perspective or having parts of the model appearing to be further or closer than they actually are.

Below is the Penrose triangle (an impossible object) that was first created by the Swedish artist Oscar Reutersvärd in 1934. The mathematician Roger Penrose independently devised and popularized it in the 1950s, describing it as “impossibility in its purest form.”

A 3D-printed version of the Reutersvärd Triangle illusion, its appearance created by a forced perspective.

So what does all this have to do with MCADCafe?
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