Zoetropes Explained

A Zoetrope is one of those things that is pretty easy to understand the physics, but unless you have run into one of these before, you probably have no idea what it is. I experienced the awesomeness of a Zoetrope during my latest trip to Disneyland, and felt it was one of those little things everyone should see in person at least once. It is one of the easiest ways to show people how the animation process works.  If you are ever in Disney's California Adventure, head over to the Disney Animation Building and check it out.

A classic zoetrope.

What is a Zoetrope?

You have likely seen a zoetrope before.  It is simply a spinning device that creates the illusion of movement through the use of pictures and a framing mechanism.  The classic zoetrope, like the one on the right, is a cylinder with images painted around the inside wall, and as a framing mechanism uses slits that create a static image in your mind.  When spun at a certain rate, your eyes see a series of static images that it puts together to create motion.  I am sure everyone has seen and probably made a flip book of drawings that creates the same effect when they were children.

This is pretty easy to conceptualize.   So why am I making a big deal about it?  Aside from finding the functionality of the human brain fascinating, there are many more ways to make a zoetrope than just a cylinder with slits cut out.  Anything that spins and creates the illusion of motion is considered a zoetrope.  As an example, the zoetrope that got me excited about them in the first place is the Pixar's Toy Story Zoetrope at Disney's California Adventure.  This zoetrope is a three-dimensional model of many Toy Story characters, and the motion effect is created using a strobe light.  The effect is quite amazing.

How Does it Work?

The way the brain processes motion is actually a little weird.  You don't actually see a fluid scene in front of you with people and objects moving seamlessly through your field of vision.  What you see is a series of still images that your brain processes and creates the perception of viewing motion.

You may have heard the eye can see at a frequency of 60 hertz (or a 'frame rate' of 60 frames per second).  That is more or less true, though the ability for your brain to process snapshots is dependent on the size of the image you are viewing, lighting, and the distance the object is from you.  Sixty turns out to be about the maximum frequency which your brain can process.

A zoetrope, as well as televisions, computer monitors, movie screens, and video cameras, all take advantage of this process.  Each records or displays a moving image in exactly the same way the brain 'sees' them.  This is actually convenient, because this also happens to be the easiest way to create the illusion of motion. The result is the appearance of fluid motion, even at frame rates as low as 24 frames per second, like you would see in most movies.  In the case of a zoetrope, however, the frame rate is almost always lower, which results in choppy motion.

History of Zoetropes

The first known device that would be considered a zoetrope was actually created over 2000 years ago in China.  This zoetrope was designed to hang over a lamp where the convection current created by the heat from the lamp flowed over vanes at the top of the device and caused it to spin.  This in turn spun a series of translucent paper panels that gave the appearance of motion when moving at the right speed.

The more modern zoetrope was invented by the mathematician William George Horner in 1833, though he called it the 'daedalum' or 'wheel of the devil'.  His invention did not become popular until the 1860s and was patented in England  and in America.  The name 'zoetrope' was coined by American developer William F. Lincoln, which in Greek means 'wheel of life'.  

Modern Zoetropes

The zoetrope seems to have become more popular in recent years.  In the New York subway system is a linear zoetrope built into an unused subway station.  As the train passes by, riders get a short show.

A few years ago, Sony built a giant zoetrope they called the Bravia-drome in Venaria, Italy.  This is by all accounts the largest zoetrope ever created, though it is far from the coolest in my opinion.



The inspiration for the three-dimensional Pixar's Toy Story Zoetrope came from another 3-D zoetrope in the Ghibli Museum in Tokyo.  While this one is pretty awesome, it doesn't quite live up to the Toy Story one in Disney's California Adventure.



And finally, there is the Toy Story Zoetrope in California Adventure.  I chose this video because is in preceded by a short explanation of animation by some of the Pixar animators.  It looks pretty cool in the video, but this is something you really need to go see in person.  I hope it remains there for some time to come.