The eye tracking technology is based on devices able to determine the pupil or cornea position with reference to a fixed preset point. Such devices need two different tuning phases: one to fix the reference to the above point and an other, specific for each user, to adjust itself to the particular eye configuration. The equipment is generally made up by a videocamera shooting the eye and by specific software able to transmit to an user application the co-ordinate of the gaze position on the screen (Quick Glance by Eyetech Digital Systems and Eyegaze by LC Technologies).
The above-mentioned devices are extremely accurate in recording even slight movements of the gaze, yet they show some drawbacks making them little suitable to public applications: in fact, it's possible that they don't work at all with some particular eye configurations, and in any case the length of the preparing phase is not always compatible with exhibit requirements.
An alternative solution, proving to be effective when the eye-image distance is large enough to require slight movements of the head for viewing, is the use of movement tracking devices based on sensors integral with the observer. In such a case an infra-red sensitive videocamera records the position of a little reflecting dot placed on the head of the user and lighted by an infra-red ray source (TrackIr by NaturalPoint). This solution, though less natural than direct eye tracking, nevertheless has the advantage of great ease of use making it at present the fitest solution for artistic aims.
all texts and images by Stefano Coluccini © 2002 S. Coluccini