Crater

HOW

1. Look at the pattern on the stationary disc.
2. Start rotating it.
3. Slowly increase the spinning speed. What can you see?
4. Experiment by rotating the disc at different angular speeds, in both directions. At low spinning speed, you will get the impression that the object being rotated is three-dimensional.

WHY

The arrangement of the lines and their thickness on the rotating disc make the object appear three- dimensional. Thicker lines are recognised as closer and thinner lines as further away.

When looking at an object, the image enters each eye from a slightly different angle. This enables the brain to judge the distance to the object. This mechanism is the basis of spatial vision. However, it is worth knowing that it is also possible with one eye. This is because the brain uses more phenomena to interpret the image. The size of objects or the arrangement of shadows, for example, can be significant.