Apple Inc.
Glint-Based Gaze Tracking Using Directional Light Sources

Abstract:

Various implementations determine gaze direction based on a cornea center and (a) a pupil center or (b) an eyeball center. The cornea center is determined using a directional light source to produce one or more glints reflected from the surface of the eye and captured by a sensor. The angle (e.g., direction) of the light from the directional light source may be known, for example, using an encoder that records the orientation of the light source. The known direction of the light source facilitates determining the distance of the glint on the cornea and enables the cornea position to be determined, for example, based on a single glint. The cornea center can be determined (e.g., using an average cornea radius, or a previously measured cornea radius or using information from a second glint). The cornea center and a pupil center or eyeball center may be used to determine gaze direction.