| Typical eye tracking methods require a calibration process to obtain the geometrical positions of the camera, the visual display, and the eyes. This thesis presents a novel method of eye gaze estimation, one without a need for calibration or knowledge of the aforementioned geometrical properties.;The calibration-free (CF) method exploits the refractive characteristics of the corneal surface as well as the retro-reflective behaviour of the eye.;Infrared light emitting diodes (IR LEDs) are used to mark the perimeter of a visual display. The reflection of these markers on the cornea provide a reference to where the visual display is in relation to the viewer's field of view. Secondly, a viewer's focus of attention is synonymous with the pupil centre. Thus by observing where the pupil centre lies relative to the corneal reflections of the IR markers, it is possible to estimate where the subject is looking. To map the location of the pupil centre to coordinates on the visual display, a novel interpolation routine is presented.;The method is implemented as a prototype CF eye tracker and design considerations are discussed. The CF prototype provides a non-intrusive means for eye gaze estimation. The prototype is easier to use than conventional techniques, and simpler and more economical to construct than currently available commercial systems. |
