Visual display with illuminators for gaze tracking
A visual display characterized by hidden reference illuminators is adapted to emit invisible light for generating corneo-scleral reflections on an eye watching a screen surface of the display. The tracking of such reflections and the pupil center provides input for gaze tracking. A method for equipping and an LCD with a reference illuminator are also provided. A system and method for determining a gaze point of an eye watching a visual display comprising reference illuminators are further provided. The determination of the gaze point may be based on an ellipsoidal cornea model.
1. A system for determining a gaze point of an eye watching a visual display, the visual display comprising a plurality of reference illuminators adapted to emit invisible light, and a screen surface adapted to display graphical information based on the plurality of reference illuminators arranged beneath the screen surface, the system comprising:
a camera for acquiring an image of the eye including corneo-scleral reflections of the reference illuminators; and
a processor adapted to
define, based on the locations of the corneo-scleral reflections in the image plane, a mapping between a coordinate system in the object plane and a coordinate system in the image plane; and
determine, based on the mapping, the eye's gaze point in the object plane coordinate system, with the mapping comprising an ellipsoidal reflection mapping and a perspective projection.
2. The system according to claim 1 , wherein said is arranged near a lower edge of a screen surface of the visual display.
3. A method for equipping a liquid crystal display with a reference illuminator adapted to emit a beam of invisible light, the liquid crystal display comprising a screen surface adapted to display graphical information; a plurality of layers, which are operable to be translucent, arranged beneath the screen surface and essentially parallel therewith; and at least one opaque layer arranged beneath the plurality of layers, the method comprising the steps of:
a) providing a hole in the at least one opaque layer, the hole being commensurate with the beam of light; and
b) fixing, using a fastener, the reference illuminator in such a manner that the beam of light is essentially perpendicular to the screen surface and concentric with the hole.
4. A method for determining a gaze point of an eye watching a visual display comprising the steps of:
a) illuminating the eye by invisible light from a plurality of reference illuminators provided in an object plane;
b) acquiring an image of the eye including corneo-scleral reflections of the reference illuminators;
c) defining, based on the locations of the corneo-scleral reflections in the image plane, a mapping between a coordinate system in the object plane and a coordinate system in the image plane; and
d) determining, based on the mapping, the eye's gaze point in the object coordinate system, with the mapping comprising an ellipsoidal reflection mapping and a perspective projection.
5. The method of claim 4 , wherein the ellipsoidal reflection mapping comprises a prolate spherical reflection mapping.
6. The method according to claim 4 , wherein the reference illuminators are arranged beneath a screen surface, adapted to display graphical information, of the visual display.