I See What You See: Point of Gaze Estimation from Corneal Images

• Published in: Proceedings - IEEE Computer Society Conference on Pattern Recognition and Image Processing pp. 298 - 304
• Main Authors: Nitschke, Christian, Nakazawa, Atsushi, Nishida, Toyoaki
• Format: Conference Proceeding
• Language: English; Japanese
• Published: IEEE 01.11.2013
• Subjects: analytic forward projection; Calibration; Cameras; Cornea; corneal imaging; Estimation; eye gaze tracking; gaze reflection point; human computer interaction; Optical imaging; point of gaze; spherical mirror; Three-dimensional displays; Visualization
• ISSN: 0730-6512
• DOI: 10.1109/ACPR.2013.84

Eye-gaze tracking (EGT) is an important problem with a long history and various applications. However, state-of-the-art geometric vision-based techniques still suffer from major limitations, especially (1) the requirement for calibration of a static relationship between eye camera and scene, and (2) a parallax error that occurs when the depth of the scene varies. This paper introduces a novel concept for EGT that overcomes these limitations using corneal imaging. Based on the observation that the cornea reflects the surrounding scene over a wide field of view, it is shown how to extract that information and determine the point of gaze (PoG) directly in an eye image. To realize this, a closed-form solution is developed to obtain the gaze-reflection point (GRP), where light from the PoG reflects at the corneal surface into a camera. This includes compensation for the individual offset between optical and visual axis. Quantitative and qualitative evaluation shows that the strategy achieves considerable accuracy and successfully supports depth-varying environments. The novel approach provides important practical advantages, including reduced intrusiveness and complexity, and support for flexible dynamic setups, non-planar scenes and outdoor application.