The perspective door
The magnetic figures can be moved around and placed at different locations. The background has been painted according to classic rules of perspective to create a feeling of depth.
Using different perspectives makes it possible to trick the brain. This is actually a two-dimensional image, but by making the pillars in the image different sizes, we have created the illusion of a three-dimensional space. The fact that objects seem smaller at a distance than close to the observer is called perspective. The image you are looking at is painted using a one-point perspective, or central perspective, where the door at the end of the room is the focal point. Central perspectivity can be described as what happens when parallel lines, in an image drawn in a direction away from the observer, create the image of a decreasing distance. In other words, the scale gets smaller as the distance grows. The door at the back of this picture will, for example, get twice as small if you move a metre further back.