This is a perception-related exhibit.
The changing perception of height results from the way our brain uses the cues inside the room the floor and the ceiling of which are geometrically different from what we normally find in rooms. We generally decide the heights of a persons in a room by observing the distance between the top of their heads and the ceiling. The lesser the distance, greater is the height of the person. This is valid for a normal room the geometry of which is usually that of a cuboid.

The room here is very different. The floor and the ceiling are tilted such that the distance between them is varying. As a result the distance between a person head and the ceiling decreases or increases as he or she walks along the wall from the end close to the door towards the end opposite to the hole or vice versa. Hence the person observing this from the hole perceives gigantism/dwarfism