眼動儀與互動介面設計 廖文宏 6/26/2009

Outline Introduction Mobile eye tracker construction Head-mounted eye tracker Remote eye tracker Head movement compensation Human computer interface (HCI) applications Conclusions

Introduction An eye tracker is a device for measuring eye positions and eye movements. The most popular variant uses video images from which the eye position is extracted. Input source: visible spectrum vs. infrared

Eye Tracking at NCCU CS: Past Scan path analysis using high speed iView X data. Head mounted eye tracker for eye scrolling, eye gaming and eye typing. scene camera eye camera

Eye Tracking at NCCU CS: Present Improve the pupil detection algorithm to alleviate corneal reflection problem. Enhance the accuracy by compensating for head movement. Construct and test a remote eye tracker. More HCI applications using the remote eye tracker. Use the eye tracking device to assist mobile user interface design.

System Architecture Eye image Calibration process Preprocessing 9 pairs of points Pupil detection Calibration Gaze point projection Scene image

Pupil Detection Step 1: Feature detection Step 2: Noise removal edge detection with constrains on neighboring dark points. excludes edges created by bright spots apply erosion Step 2: Noise removal Head mounted eye tracker Remote eye tracker Step 3: Fitting the ellipse using singular value decomposition

Allowing Head Movement: Head Mounted Eye Tracker Use red markers on the LCD screen as the references for head movement calculation. Required information: Ratio between distance of makers in the projected image and in real: (dyWidthSclale,dyHeightScale) Head movements: (difX,difY) Correction made:

Compensate for head movement (error/standard deviation) Experimental Results Calibration point Original error Compensate for head movement (error/standard deviation) 1 98.17 32.91 (12.7) 2 137.54 55.89 (10.94) 3 108.20 29.69 (9.57) 4 76.30 28.79 (21.19) 5 113.30 22.49 (7.79) 6 117.86 34.83 (10.96) 7 116.53 33.31 (8.01) 8 112.56 16.03 (6.78) 9 146.73 26.49 (9.66) 1 cm = 38 Pixels

Allowing Head Movement: Remote Eye Tracker Use makers placed on the glasses as references. Requires an additional calibration step Fixate on the same spot, and turn the head up, down, left and right. Record the shift amount of the markers: (markXｉ,markYｉ) and movements of the pupil: (pupilXｉ,pupilYｉ) Correction made:

Compensate for head movement (error/standard deviation) Experimental Results Calibration point Original error Compensate for head movement (error/standard deviation) 1 238.73 39.69 (24.6) 2 227.51 63.56 (22.82) 3 132.97 44.30 (21.49) 4 222.97 51.66 (30.94) 5 306.58 31.15 (16.71) 6 280.79 51.66 (21.83) 7 311.89 69.03 (41.57) 8 344.24 69.88 (31.71) 9 347.03 64.66 (24.41)

Demo: Head Mounted Eye Tracker

Demo: Web Browsing

Demo: Photo Viewing

Demo: Dynamic Scene

Demo: Remote Eye Tracker

Demo: Tic-Tac-Toe

Summary Enhance the reliability of pupil detection. Improve the accuracy by compensating for head movements. Promising results for both head mounted and remote eye trackers. Interactive HCI applications.

Eye Tracking at NCCU CS: Future Faster, more accurate eye tracking. More intuitive calibration process. Developing gaze-based digital interactive media.

http://www.cs.nccu.edu.tw/~whliao/dct/