Abstract
Cornea radius estimation is a key technique for 3D gaze estimation in the single-camera 3D gaze tracking system. Traditional methods with one-camera-one-light-source systems or one-camera-two-light-source systems cannot achieve 3D gaze estimation. The 3D line-of-sight can be estimated only when the cornea radius is pre-calibrated by the user. A cornea radius calibration method based on the iris radius is proposed in this paper for 3D gaze estimation in remote one-camera-two-light-source systems. We first calibrate the iris radius based on the binocular strategy, estimate the spatial iris center using the calibrated iris radius, and then calibrate the cornea radius by a set of non-linear equations under the constraint of equivalent distances from the cornea center to the iris edge points. The calibrated cornea radius is verified by binocular optimization constraints. Simulations and physical experiments validate the effectiveness of the proposed method. The iris-based cornea radius calibration approach is novel; it can be used to obtain the cornea radius and 3D gaze using remote one-camera-one-light-source or one-camera-multi-light-source systems.
Highlights
Gaze tracking technology involves the use of electronic, mechanical, optical, and other detection methods to obtain a given subject’s current ‘‘visual attention’’
This paper proposes a cornea radius calibration method based on iris radius and binocular optimization for 3D gaze estimation via remote OCTLS system
The cornea radius calibration method proposed in this paper solves the problem that traditional methods cannot achieve 3D gaze estimation in this typical gaze tracking system, and achieves comparative gaze accuracy based on the realization of 3D gaze estimation in such a system, which meets the needs of the application
Summary
Gaze tracking technology involves the use of electronic, mechanical, optical, and other detection methods to obtain a given subject’s current ‘‘visual attention’’. The camera captures human face and eye images, extracts gaze feature parameters, and determines the mapping model with individual differences as per user calibration to calculate the intersection of the LoS and the computer screen as the PoR. The cornea radius must be user-calibrated to achieve 3D gaze estimation on typical remote systems, the cornea center can be calculated in real time and the pupil center can be further calculated to construct the OA of the eyeball during gaze estimation. The contribution of this paper mainly lies in: (1) It is proved that in a typical remote OCTLS system where the camera and the two light sources are basically collinear, the condition for achieving the 3D gaze estimation is that the cornea radius is known.
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