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Introduction
Eye-gaze as a form of human machine interface holds great promise for improving the way we interact with machines. Eye-gaze tracking devices that are non-contact, non-restrictive, accurate and easy to use will increase the appeal for including eye-gaze information in future applications. The system we have developed and which we describe in this paper achieves these goals using a single high resolution camera with a fixed field of view. The single camera system has no moving parts which results in rapid reacquisition of the eye after loss of tracking. Free head motion is achieved using multiple glints and 3D modeling techniques. Accuracies of under 1° of visual angle are achieved over a field of view of 14x12x20 cm and over various hardware configurations, camera resolutions and frame rates.
1.1 Eye Gaze Tracking Under Natural Head Movements
Most available remote eye gaze trackers based on Pupil Center Corneal Reaction (PCCR) technique have two characteristics that prevent them from being widely used as an important computer input device for human computer interaction. First, they must often be calibrated repeatedly for each individual; second, they have low tolerance for head movements and require the user to hold the head uncomfortably still. In this paper, we propose a novel solution for the classical PCCR technique that will simplify the calibration procedure and allow free head movements. The core of our method is to analytically obtain a head mapping function to compensate head movement. Specifically, the head mapping function allows to automatically map the eye movement measurement under an arbitrary head position to a reference head position so that the gaze can be estimated from the mapped eye measurement with respect to the reference head position. Furthermore, our method minimizes the calibration procedure to only one time for each individual. Our proposed method will significantly improve the usability of the eye gaze tracking technology, which is a major step for eye tracker to be accepted as a natural computer input device.
Eye Gaze is defined as the line of sight of a person. It represents a person’s focus of attention. Eye gaze tracking has been an active research topic for many decades because of its potential usages in various applications such as Human Computer Interaction, Eye Disease Diagnosis, Human Behavior Study, etc. Earlier eye gaze trackers were fairly intrusive in that they require physical contacts with the user, such as placing a reactive white dot directly onto the eye or attaching a number of electrodes around the eye. Except the intrusive properties, most of these technologies also require the viewer’s head to be motionless during eye tracking. With the rapid technological advancements in both video cameras and microcomputers, eye gaze tracking technology based on the digital video analysis of eye movements has been widely explored.