Missing Corner Cube

This ambiguous cube has three aspects, or ways of seeing the cube. The cube can also be animated. See if you can visualize each of the aspects below before you animate the cube.

Aspect one: a normal looking cube with a corner piece missing in the front.
Aspect two: a hollow three-sided room with a smaller cube sitting in the back corner.
Aspect three: a smaller cube is floating in front of the larger cube.

Now comes the amazing part. Animate the cube by dragging your mouse back and forth across the image. Try to visualize each of the three aspects as you rotate the cube. You will find that aspects one and two are fairly easy to hold. Aspect three is a whole other kettle of fish! In aspect three, the large and small cubes will rotate in opposite directions. How can this happen?

Applet & Art: ©2001 A. Azevedo