Anamorphic art is a technique of drawing images based on a distorted projection, that can only be fully understood from a specific point or angle. In mirror anamorphosis, an image is formed by a distorted mirror (usually a cylinder) placed near an abstract image or sculpture. In some cases, the correct image will only appear if viewed through a mirror. Anamorphosis artworks look a particular way face on, yet change when you move to the left or right.
The technique was invented in the late Renaissance (16th century) but there are many contemporary artists that use this technique today
Here are two short videos of some examples: