The Ames rooms causes two people of equal size to appear very different in size. The reasoning for this crazy perception is in the construction of the room. The walls and windows appear to be the same size, when in reality they are completely different, tricking our eyes to see this illusion. The explanation for the Ames Room illusion is relative size. The relative size explanation states: Our perception of the size of two women is determined by how they fill the distance between the bottom and top of the room. I find this illusion completely fascinating.
The following video gives a 3D explanation about the Ames Room.