Jul 4, 2016 | By Alec

It was almost impossible to miss. A few days ago, the internet became mesmerized by a remarkable optical puzzle by Japanese illusionist Kokichi Sugihara. Called the 'Ambiguous Cylinder Illusion', it featuring sets of plastic squares that turn into circles when reflected in front of a mirror. Even more mind-boggling, the effect is reversed when the model is reversed by hand. Fortunately, the mystery was quickly solved by 3D printing specialist Devon from Make Anything, who reverse-engineered the model to reveal that the shapes were neither circles or squares: but simply a shape that was right in between. Combined with the engrained perception conventions of our brains, the fantastic illusion is created.

It was one of those videos that showed the power of the internet. A video of Kokichi Sugihara’s illusion (visible below) was posted on Reddit a few days ago, after which it quickly reached the far corners of the web. “The direct views of the objects and their mirror images generate quite different interpretations of the 3D shapes. They look like vertical cylinders, but their sections appear to be rectangles, while in the other view they appear to be circles,” Sugihara said.

The video’s impact was huge. Collectively, the world wondered how on earth the shapes can transform through simple reflection. Engineer and artist Kokichi Sugihara created the installation for the Illusion of the Year contest, in which he ultimately won the second prize. But of course there’s more to it than simple amazement. The Illusion competition emphasizes that they are seeking to expand our understanding of how our brains process information. “How we see the outside world – our perception – is generated indirectly by brain mechanisms, and so all perception is illusory to some extent. The study of illusions is critical to how we understand sensory perception, and many ophthalmic and neurological diseases,” they state.

Ultimately, the solution could therefore be found in how our brain processes visual information. In fact, the solution came within hours of the first clip coming online. Devon from 3D printing specialists Make Anything quickly posted a video called ‘Ambiguous Cylinder Illusion/How It Works’, which explained the trick.

As it turned out, the objects in question are neither circles or squares, but simply right between the two. What’s more, the square sides curve upwards, while he circle sides slop downwards, completing the illusion. As a result, it can appear as a circle or a square depending on the angle you’re viewing it in. The different heights correct the geometric differences that are created. As a result, our brains – which are used to distinguishing between circles and squares – see what they expect to see.

It’s a very clever trick that underlines the ‘limitations’ of our own sensors. “We cannot correct our interpretations although we logically know that they come from the same objects,” Kokichi Sugihara explained. “Even if the object is rotated in front of a viewer, it is difficult to understand the true shape of the object, and thus the illusion does not disappear.” If you want to try it for yourself, you can download the STL file for Devon’s 3D printable cylinder on Thingiverse here.



Posted in 3D Printing Application



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