Research On Long-distance 3D Gaze Calibration And Eye Gaze Tracking

Gaze estimation,or eye tracking,is a technique to estimate the drop point of the line of eye sight,that is,where the eye is looking.It can be divided into 2D gaze estimation and 3D gaze estimation.2D gaze is generally the fixation point on the computer screen,which is used for the human-computer interaction and web page analysis.3D gaze is the fixation point in 3D space,which can be used for safety assistance driving.3D gaze estimation can be calculated on the basis of 2D gaze estimation through the intersection of binocular line of eye sight.The main research contents of this paper are as follows:(1)Research and compare the methods of pupil localization and eye feature point extraction,including the methods based on light-dark pupil effect,CNN model and template matching.Starburst algorithm was used for pupil contour detection,and RANSAC algorithm and least square method were used for ellipse fitting of the detected pupil edge points to obtain the pupil center coordinate.(2)Research on the mapping methods from eye feature points to 2D fixation points,including the second-order nonlinear polynomial mapping method and BP neural network mapping method.Designing network structure,taking eye images and making training data set,and training the mapping model.Finally,the calibration and image processing program were written to perform the real-time calculation of 2D fixation points on the screen and the display of gaze trajectory.(3)Research on the 3D gaze estimation based on binocular lines of sight intersection.For the difficulty of measuring the 3D coordinates of the eyeball optical center,we proposed a calibration method for eyeball optical center measurement by gazing the calibration plane which can move forth and back.For the estimation in distance direction of 3D fixation point,there is a big jitter,we proposed a data filtering and Z-plane intercept correction method to reduce the estimation error.Within the test distance of 30 ? 50 cm,the angle error of 3D fixation point is 0.7°,and the Euler distance error is 17.8 mm.(4)Research on the 3D gaze estimation for a longer distance.Because the binocular line of sight trend to be parallel with the increase of gaze distance,it is difficult to figure out the exact intersection of the lines of eye sight,we proposed a method to detect object information of scene by millimeter wave radar for assisting3 D fixation point estimation.In addition,we proposed a method to calibrate 2D fixation points in large space by forming a virtual calibration plane with movable calibration objects.Finally,the experiment device was designed and built,and the corresponding upper computer software for experiment was written.Within the test distance of 4 ? 10.2 m,the angle error of 3D fixation point is 0.9°,and the Euler distance error is 130 mm.