User-calibration-free remote eye-gaze tracking system with extended tracking range

A novel general method to extend the tracking range of user-calibration-free remote eye-gaze tracking (REGT) systems that are based on the analysis of stereo-images from multiple cameras is presented. The method consists of two distinct phases. In the brief initial phase, estimates of the center of the pupil and corneal reflections in pairs of stereo images are used to estimate automatically a set of subject-specific eye parameters. In the second phase, these subject-specific eye parameters are used with estimates of the center of the pupil and corneal reflections in images from any one of the systems' cameras to compute the Point-of-Gaze (PoG). Experiments with a system that includes two cameras show that the tracking range for horizontal gaze directions can be extended from ±23.2° when the two cameras are used as a stereo pair to ±35.5° when the two cameras are used independently to estimate the POG.