Study On Eye Tracking In Free Space Based On Stereo Vision

The eye tracking is the key technology of intelligent eye movement operating system, which also is the basis that enables eye movement operating system to be the advanced human-machine interactive applications. In the initial stage of eye tracking, measurment methods had great disturbance of people. Recently, with the development of machine vision and technology of image processing, non-contact eye gaze tracking technology that utltizes method of vision to track the movement of eyes and applies image process to analyze gazing direction is widely applied.This paper gives a vision of development of non-contact eye tracking technology, and introduces the non-contact eye gaze tracking technology that enables to achieve real-time dynamic eye tracking or gaze point estimation, including 2D eye tracking methods, 3D eye tracking methods and Model-based 3D methods. 2D eye tracking methods highly relied on calibration mapping plane and only obtained 2D viewpoint information 3D eye tracking methods cannot take freedom movement of head and high-precision eye image tracking into account at the same time, and the process of spatial calibration is complicated. Aiming at the existing problem, this paper presented a novel head-mounted 3D eye tracking method based on binocular stereo vision. This method based on binocular stereo vision measurement model, it combines with epipolar constraint to achieve accurate pupil center and pose of the supporting plane of the pupil contour in 3D. After that to define the normal direction of the circle plane of the pupil edge in single eye is the optical axis.The definition is different from common pupil-corneal reflection method, which has more strict 3D expression.First of all, constructing the head-mounted free space vision measurement device based on its measuring model, including model selection of the binocular camera and viewfinder camera, manufacture of the half mirror and hood that meet the principle of Ergonomics. Secondly, fulfilling the head-mounted free space vision measuring model based on binocular stereo vision needs measurement of defined optical axis. The measurement of defined indirect estimated vision direction mainly includes calibration of binocular camera, matching of pupil edge points, and gesture calculation of the pupil in round plane space. The matching process of pupil edge points is based on limit constraints, we applied methods based on camera projection matrix and SURF+RANSAC to calculate fundamental matrix to achieve corresponding points matching at pupil edge. It turns out that the two methods result is all good. The speed of fist method is quicker.This paper proposed the eye tracking method in free space based on binocular stereo vision, can solve the problems that freedom of head movement and precision eye image cannot achieve both and spatial calibration process complex. At the same time can get the 3D line of sight.