• The Best Illusion of the Year contest named its 2018 winner: "Triply Ambiguous Object" by Kokichi Sugihara.
  • The object looks completely different from three different viewpoints.
  • It's actually two-dimensional picture that appears to be three-dimensional from a slanted angle.
  • The illusion only works on camera.

The Best Illusion of the Year contest naturally chose a mind-boggling winner.

"Triply Ambiguous Object" created by Kokichi Sugihara of Japan shows what appears to be a three-dimensional object looking completely different from three different viewpoints. These seemingly different objects can all be seen at the same time thanks to two vertical mirrors placed behind it.

Here's a video of what the illusion looks like:

Most optical illusions like this, such as Schroeder's Stairs, only offer two different interpretations from different viewpoints. How did Sugihara pull off three?

There are three reasons why the illusion occurs.

Firstly, the viewer is seeing it on video, not in person.

"If we see the artwork directly, we cannot enjoy the illusion," he wrote. "We have two eyes, and can detect the distance to the object surface by binocular stereo, and consequently we perceive a horizontally oriented picture."

Watching a video of the illusion is the equivalent of seeing it with one eye, as some depth perception is absent.

Our brains fill in the missing depth information with rectangles.

The object itself is two-dimensional and doesn't contain depth information, but our brains fill it in with rectangular objects, making it appear three-dimensional.

"There are infinitely many possibilities of 3D structures whose projections match the 2D image," Sugihara wrote. "Among them, our brains usually choose the interpretation containing many rectangles."

The pin represents the direction of gravity.

The vertical pin emphasizes the direction of gravity when viewing the object on a slant, strengthening the illusion of a three-dimensional space.

"When we see the artwork in a slanted direction, we feel that we are seeing something in the 3D space instead of just seeing a picture facing toward ourselves," he wrote.

It's hard to tell that the three viewpoints are showing the same object, making this illusion a worthy first place winner.

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