Shaded Bar 3D Optical Illusion

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This optical illusion is impossible since one side ends with one bar while the other side ends with two.

Explanation

The optical illusion occurs because our mind tries to convert a two dimensional object into three dimensions. We try to assign 3D aspects to this illusion which are not there.

In this optical illusion, our mind sees two bars on the right end and only one bar on the left. That is, of course, impossible. It is the shadow on the left side that throws us off. If you cover the shadow on the left, it will look like there are two bars on that side, also. Since the shadow is the same color as the side of the bar, our mind converts the whole bar on that end into a shadow.

The optical illusion is compounded by the use of perspective angles. On the left side, the angles used at the end of the nearest bar are not correct and fool us.