Tales from the Prep Room: The Ames Room

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How to build a life-size optical illusion.

The Ri's Andrew Marmery takes a break from Christmas Lecture rehearsals to describe how he designed and built a life-size Ames room for the show.

The distorted room was named after ophthalmologist Adelbert Ames, who invented the optical illusion in 1934. The floor, ceiling and side walls of the room are trapezoidal in shape but when viewed from a specific fixed point it appears to be rectangular.  As Andy demonstrates, anyone standing inside the room appears unusually large or unexpectedly small.


Being Human, Engineering


Andrew Marmery
London, UK
Filmed in:
The Ante Room


Collections with this video:
Tales from the Prep Room, CHRISTMAS LECTURES 2011 - Meet Your Brain

cc_by-nc-sa License: Creative Commons

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  • The finished Ames Room outside the Theatre.

    Image: The Royal Institution



So we recorded Lecture one last night, and we're just rehearsing Lecture three, I think, at the moment. So it's surrounded by the paraphernalia of the Lectures to come. But I just wanted to take a moment to tell you about the Ames room behind me, which was one of the demos from last night. I don't think we actually mentioned it was called an Ames room.

It's named after Adelbert Ames, which is a great name, who was an ophthalmologist. I don't know what he was doing inventing distorted perspective rooms like this but he did.

So quite early on, we decided we wanted to build one of these on this scale.

I was hoping, Andy, you might be able to make an Ames room for us.

Yeah, I like that comment. Did you notice that -

Oh, I didn't see that actually. No, that'd be really good fun.

It has to be fairly large.


Choose two kids who are the same height, and you can measure them up and then be sure and then they walk into it, and they walk backwards and forwards, and you literally see them growing. And it's extraordinary.

We started looking on the net for plans of how we might do this. Downloaded a couple which seemed not particularly good, so we thought we'd do all the calculations ourselves and work out exactly how to go about building this. So that manifested itself in fairly complicated spreadsheets, which gave rise to prototype one, which is here.

I don't think you can really see into it through that hole. But you look through that hole, and you see... If I look through, I can just about see a room.

So this gave me the confidence that we could make something roughly right. So the next stage was to build a slightly more serious scale model of what we wanted to build. Roughly a one-tenths scale of the main. Once we'd made this, I was pretty confident that we could make the real thing and make it look good. I hadn't anticipated some of the woodwork challenges that were to come.

So this took about three or four days work to build. And when I say days, I'm talking 24 hours, basically. It's almost nonstop work on this. There were three of us, me and Mellis and Gaz making this room.

Some of the beams at the far end, there's some really weird double compound cuts going on. So it's pretty complicated stuff. And one of those days was just decorating it, and finding some nice pictures from the collection, which is quite a nice touch, I think. We probably finished off the floor about 45 minutes before the start of the show last night. So it was typical last-minute stuff.

It was really great to see it work as well as it did on camera last night. It was really fantastic.

If you did ever wonder what on earth you learned trigonometry for, this is it right here.

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