(1) Lightweight Eyetracking Headgear (RIT):
Figure 1.1 shows the eyetracking headgear that I helped develop while I was at the Visual Perception Lab
at RIT. The headgear construction greatly simplifies the optics by using a microlens video camera (pointed at the eye) and a single infrared LED for "dark-pupil" eyetracking. The goal was to develop a simple eyetracking device that could be constructed from off-the-shelf parts. I have recently made this headgear compatible with my own custom eyetracking software
for Mac OS X Tiger. Figure 1.2 shows a close-up of the microlens camera used to monitor the eye.
More on Dark-pupil
Like many video-based eyetracking systems, this headgear uses an infrared source to illuminate the eye. Figure 1.2 shows the small infrared LED (IRED) positioned next to the eye camera. This configuration is called dark-pupil illumination since the infrared falling into the pupil gets absorbed inside of the eye (instead of being reflected, as in the bright-pupil technique). The eye image in Figure 2.1 also shows the typical characteristics of a dark-pupil eye image.
An adjustable voltage regulator drives the LED, and a potentiometer is used to tune the LED circuit to the desired voltage and correct brightness. An 87c Wratten filter is placed over the camera sensor to block visible light so that only an infrared image can pass. This illumination configuration provides clear pupil and corneal glint boundaries that are easy to track.
While looking at a series of points in the scene, the vector distance between the center of the pupil and the center of the corneal reflection (resulting from the IRED) can be mapped to corresponding points in the scene using a simple linear mapping. This "calibration" can be used to map eye position to where the person is looking in the scene camera.
The headgear is designed so that minimal adjustment is needed to acquire a good image of the eye. Repositioning the eye camera is easy since it is mounted on flexible wire.
For more details read the PDF:
Babcock, J.S., and Pelz, J. (2004). Building a lightweight eyetracking headgear, ETRA 2004: Eye Tracking Research and Applications Symposium, 109-113.