Is this a triangle?
Cover the top of the triangle with your hand and then see what happens?

The Orbison illusion is an optical illusion that was first described by the psychologist William Orbison in 1939. The bounding rectangle and inner square both appear distorted in the presence of the radiating lines.

The background gives us the impression there is some sort of perspective. As a result, our brain sees the shape distorted. This is a variant of the Hering and Wundt illusions.

The upper side of the left-lower triangle is actually aligned with the upper side of the right-upper triangle, the former appears to tilt counter clockwise while the latter clockwise.

Wow! This is cool. I think any one who like to walk in this floor will feel little bit dizzy while walking

At first impression most people dimples.In the absence of an obvious light source most people place an imaginary light source above the image (being earthlings living under the sun i suppose this is only natural). Because of this pre-conception we now imagine a shadow being cast at the top of the circles and light being caught on the bottom that is our assumption of where the light is coming from forces us to see indentations.

When slightly tilted line segments are aligned horizontally like the figure, the whole array appears to tilt toward the tilt of the line elements. This is a reversal of the Zollner illusion or acute-angle contraction.

Excellent illusion designs drawn by a Japanese puzzler Miwa Miwa. I have posted few of those impossible objects before also Ring, Dices and Squares

Is that Blocks are moving? The image appears to move back and forward

Is the green table wider than the red table is long?
Roll your mouse over the mask to find out.