How to construct an Ames room

The Ames room was developed by Adelbert Ames Jr as part of his research into optics and perception during the 1930s and 40s. After an early career as a painter, Ames began to explore the relationship between visual art and the scientific study of vision. He studied opthalmology at Clark University, Massachusetts and became a professor of physiological optics, developing an interest optical illusions. As part of his research, he conducted a series of experiments that he called 'the distorted room demonstrations'.

When viewed from the correct position, an Ames room gives the illusion of a standard orthogonal room. It is actually a trapezoid shaped space, which means that people standing in different corners at the back of the room and who appear to be the same distance from the viewer, look as if they are completely different sizes. The optical illusion is so convincing that someone walking across the back of the room appears to increase or decrease in scale as they move from one side to the other.

An Ames room is constructed by plotting the visual rays from the chosen view point to the various points of the notional orthogonal room. Points in the Ames room can then be established on the same visual rays, either closer or further from the view point. The following example is quite a simple version of an Ames Room, where the floor and ceiling slope, but with walls that are still vertical. The dimensions of the wall on the right hand side have been reduced by exactly 50% compared to the left. The illusion can be developed further with sloping wall surfaces, whilst still maintaining the apparent appearance of an orthogonal space.

Plans, showing an orthogonal room on the left and the plan of an equivalent Ames room on the right (viewing position at bottom)

3D view showing the perceived orthogonal space

3D view showing the irregular space of the Ames room

Section through the Ames room showing visual rays

(images © copyright Russell Light)

A SketchUp model can be downloaded from the Google 3D Warehouse.


The principle of the Ames room is often used to create spatial illusions in films. Most recently, the effect has been used in the Lord of the Rings trilogy so that the hobbits would appear smaller than other taller characters.

Ames' original room also incorporated an anti-gravity illusion, that took advantage of the apparently flat floor that actually sloped. A ball would be appear to roll upwards along a grooved track that was positioned across the room.


Sources:

F Dubery & J Willats (1983) - 'Perspective and Other Drawing Systems', Herbert Press, London. Amazon link

R Gregory (1994) - 'Even Odder Perceptions', Routledge, Amazon link