Controlling computers with one’s eyes is a staple of science fiction that makes a lot more sense than Minority Report-style hand-waving. Nobody wants to swing their arms all over the place just to open the future equivalent of Facebook — it’s horribly inefficient. Simply looking at the Futureface icon with your eyes, however, is very efficient. Moving your eyes is quick and expends almost no energy. Practical eye tracking is still in its infancy, and can often be quite expensive. But, John Evans’ open source eye tracker is affordable and seems to work well.
The goal of every eye tracking system is to simply determine what it is you’re looking at. It needs to be accurate enough to work with a traditional computing workspace, and quick enough to keep up with the fast movement of your eyes. Evan’s eye tracker achieves that, but the hardware is fairly complex. That said, the system is still very affordable, and all of the code is available so that you can build one yourself.
The primary components of the system are a pair of commercial $20 webcams, and a pair of infrared LED beacons. The beacons are stationary, and should be placed around whatever you’re looking at — probably your computer screen. One of webcams points at your eyes, and uses the infrared reflections from the beacons to determine a “looking vector.” The second camera points towards what you’re looking at, and uses that looking vector to calculate where your gaze is actually falling. If you want to give it a try, Evans’ has developed a camera viewer program that will handle the math so you can get started.