US 8,824,779 B1Granted

Apparatus and method for determining eye gaze from stereo-optic views

OwnerChristopher Charles Smythinventor

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Abstract

The invention, exemplified as a single lens stereo optics design with a stepped mirror system for tracking the eye, isolates landmark features in the separate images, locates the pupil in the eye, matches landmarks to a template centered on the pupil, mathematically traces refracted rays back from the matched image points through the cornea to the inner structure, and locates these structures from the intersection of the rays for the separate stereo views. Having located in this way structures of the eye in the coordinate system of the optical unit, the invention computes the optical axes and from that the line of sight and the torsion roll in vision. Along with providing a wider field of view, this invention has an additional advantage since the stereo images tend to be offset from each other and for this reason the reconstructed pupil is more accurately aligned and centered.

Claims20

Dependent claims

A system for tracking an eye, comprising:

an optical device with a light emitting source and an optical system, wherein the light source is configured for illuminating the eye and the optical system is configured for providing multiple-images of the eye;
an optoelectronic device for acquiring an image of the eye collected by the optical system;
an image processor for isolating reflections of source illumination in the image and for isolating features of the pupil and extra-pupillary eye structure in the image, wherein isolating features comprises determining the position of such in the image and categorizing as to structure type, where the features are at least those of a pupil;
a pupil-reconstructor for constructing a model of the pupil within the eye, wherein the model of the pupil is constructed from model parameters derived from pupil image features;
a feature-matcher for matching extra-pupillary image features to a common template located by the model of the pupil;
a feature-locater for locating matched features from multiple images in a coordinate system common to the optical device;
and
a gaze processor for estimating the visual line-of sight for the eye in the said coordinate system;
wherein the multiple images are stereo-views about an optical axis of the system with centering on the eye-orbit.

6 more elements

A method for tracking the eye, comprising:

illuminating the eye;
acquiring images, at the least a single image, of the eye;
isolating reflections of the means of illumination in an image;
isolating features of the pupil and extra-pupillary eye structure in the image, wherein isolating features comprises determining the position of such in the image and categorizing as to the nature, where the features are at least those of a pupil;
constructing a model of the pupil within the eye, wherein the model of the pupil is constructed from model parameters derived from pupil image features;
matching extra-pupillary image features to a common template located by the model of the pupil;
locating the matched features in a coordinate system common to the means of acquiring an image;
and
determining the visual line-of sight for the eye in the said coordinate system.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/572,650Filed 11 Aug 2012 · continuation in part
Priority: 20 Dec 2011
Granted: 2 Sep 2014
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G06V 40/193
Eye characteristics, e.g. of the iris: preprocessing; Feature extraction
G06T 7/593
From multiple images: from stereo images
G06T 7/73
Determining position or orientation of objects or cameras: using feature-based methods
G06T 2207/10021
Video; Image sequence: stereoscopic video; Stereoscopic image sequence