Eye Tracking on the Cheap: Making MacGyver Proud

One of the more fun aspects of writing for Eye Tracking Update is when a new, do-it-yourself eye tracking device shows up online. With so many formal reports (these are also great, of course!) involving medical diagnostics and web usability studies, it’s refreshing and enjoyable to see when tinkerers start innovating on their own, on the cheap, and for no other reason than to have fun doing it.

A post that falls under all of these categories was brought to our attention, and it features a video game created by Katherine Keane that she calls I.C.U. The game was created entirely in the program Processing, and Keane, who “loved the idea of blowing up objects by looking at them” managed to combine her playful and self-proclaimed “peaceful” attitude in a comical and kid-friendly game.

She worked with an open-source physics simulation library (Processing Box2D physics library) written with game designers in mind, to create colorful explosions that incorporate weight, velocity, gravity simulation, and collision detection. After donning a pair of eye tracking glasses, Keane created a game in which she could stare at cartoon fruits, eyeing them until they explode into particles that fly all over the screen.

To make it work, the gamer stands directly in front of a projection screen and systematically stares at 12 calibration points projected onscreen while the game calibrates. The game begins and the fruit starts to appear. When the player’s eyes rest on a particular object, the object jiggles, and then quickly disappears as it’s replaced by an explosion of particles. The initial explosive force, she says, causes a burst of particles to fly in all directions, which then decelerate and fall downwards.

Some of the troubleshooting and initial problems were interesting to us. Keane said the video streaming involved in the eye tracking component of the project requires an enormous amount of processing power, and when combined with Box2D, her selected program, it slows down the frame rate significantly. For a fix, she says she’ll need to rewrite the code. Keane also writes that the eye tracking component of the game, created with a hacked PS3 Eye camera, can be oftentimes troublesome and “finicky.” But when it works, it appears to work quite well.

Her eye tracking Processing code relies on position of the pupil and the reflective glint to read where a user’s eye is focused on the screen. Keane used a single LED as a light source, as the presence of others added multiple glints and hindered effective eye tracking. The LEDs must be kept close enough to the eye so that it illuminates effectively, yet to the side far enough so they doesn’t obstruct the camera.

She based her eye tracker design off another D.I.Y. device – the EyeWriter, which we’ve covered on Eye Tracking Update a few times.

Keane’s glasses were fitted with an infrared filter to block out all but IR light, a pair of sunglasses she bought from a street vendor, a battery pack, the LED, and some alligator clips. All in all it cost about $50 to build, something MacGyver could be proud of.

Take a look at her post – she has links to codes and might even let you borrow a pair of her glasses.

I.C.U.

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