System and method for eye gaze tracking using corneal image mapping
DC
First Claim
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1. A method for eye gaze tracking, comprising the steps of:
- creating a set of reference points in a reference coordinate system;
acquiring at least one image of at least one of a user'"'"'s corneas, said image having image aspects in an image coordinate system and including reflections of said reference points;
defining a mathematical relationship between said reference coordinate system and said image coordinate system;
mapping said image aspects from said image coordinate system to said reference coordinate system using said mathematical relationship; and
computing a point of regard from said mapped image aspects.
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Abstract
A system and method for eye gaze tracking without calibrated cameras, direct measurements of specific users'"'"' eye geometries, or requiring the user to visually track a cursor traversing a known trajectory. The preferred embodiment includes two uncalibrated cameras imaging the user'"'"'s eye and haying on-axis lighting. The cameras capture images of a test pattern in real space as reflected from the user'"'"'s cornea, which is essentially a convex spherical mirror. The invention then extracts parameters required to define a mathematical mapping between real space and image space, including spherical and perspective transformations. The invention processes subsequent images of objects reflected from the user'"'"'s eye through the inverse of the mathematical mapping to determine a gaze vector and a point of regard. Alternately, a single calibrated camera may be employed with means for estimating the eye-to-camera distance. A head-mounted embodiment that may include a laser pointer is also described.
135 Citations
15 Claims
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1. A method for eye gaze tracking, comprising the steps of:
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creating a set of reference points in a reference coordinate system;
acquiring at least one image of at least one of a user'"'"'s corneas, said image having image aspects in an image coordinate system and including reflections of said reference points;
defining a mathematical relationship between said reference coordinate system and said image coordinate system;
mapping said image aspects from said image coordinate system to said reference coordinate system using said mathematical relationship; and
computing a point of regard from said mapped image aspects. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
determining for each of said cameras an angle between said focal center, a user'"'"'s pupil center, and a point on a predetermined target surface where a virtual light source would create a new image aspect at a pupil image center in said image coordinate system; and
defining a gaze vector as the bisector of said angle.
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9. The method of claim 8 comprising the further step of correcting said gaze vector for a foveal axis offset angle.
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10. The method of claim 6 wherein at least one of said cameras is head-mounted.
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11. The method of claim 1 wherein said mathematical relationship includes at least one of:
- spherical transformations, perspective transformations, polynomial interpolation.
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12. The method of claim 1 wherein said computing step includes the further steps of:
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mapping a target coordinate system to said reference coordinate system; and
bisecting a line segment spanning an on-axis glint and a pupil image center in said target coordinate system.
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13. The method of claim 12 wherein said target coordinate system is said reference coordinate system.
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14. A system for eye gaze tracking comprising:
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means for creating a set of reference points in a reference coordinate system;
means for acquiring at least one image of at least one of a user'"'"'s corneas, said image having image aspects in an image coordinate system and including reflections of said reference points;
means for defining a mathematical relationship between said reference coordinate system and said image coordinate system;
means for mapping said image aspects from said image coordinate system to said reference coordinate system using said mathematical relationship; and
means for computing a point of regard from said mapped image aspects.
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15. A computer program product including a program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for eye gaze tracking, said program comprising:
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a first code means for creating a set of reference points in a reference coordinate system;
a second code means for acquiring at least one image of at least one of a user'"'"'s corneas, said image having image aspects in an image coordinate system and including reflections of said reference points;
a third code means for defining a mathematical relationship between said reference coordinate system and said image coordinate system;
a fourth code means for mapping said image aspects from said image coordinate system to said reference coordinate system using said mathematical relationship; and
a fifth code means for computing a point of regard from said mapped image aspects.
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Specification
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Litigation Data
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Current AssigneeTobii Technology AB
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Original AssigneeInternational Business Machines Corporation
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InventorsAmir, Arnon, Flickner, Myron Dale, Morimoto, Carlos Hitoshi, Koons, David Bruce
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Primary Examiner(s)MANUEL, GEORGE C
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Application NumberUS10/034,524Publication NumberTime in Patent Office711 DaysField of Search351/209, 351/210, 351/208, 351/200, 351/205, 351/206, 351/211, 351/221, 382/103, 382/291, 708/141, 702/151US Class Current351/210CPC Class CodesA61B 3/113 for determining or recordin...G06V 40/19 Sensors therefor
