1. Mobile eye tracker construction and gaze path analysis By Wen-Hung Liao 廖文宏

2. Outline Introduction Application areas State-of-the-art technology Mobile eye tracker construction Pupil detection and tracking Validation Human computer interface (HCI) applications Gaze path analysis Conclusions

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

4. Eye Movements Eye movements are typically divided into fixations (when the eye gaze pauses in a certain position) and saccades (when it moves to another position). Eye movements The resulting series of fixations and saccades is called a scanpath.scanpath

6. Web Design (U. of Manchester) Heat mapGaze plot

7. Usability Study: Google Search Evaluation

8. Gaming

9. Driving Behavior [Andrew T. Duchowski]

10. Human-Computer Interface EyeWrite [Andrew T. Duchowski]

11. Media Research The Poynter Institute : http://www.poynter.orghttp://www.poynter.org Published first eye track study in 1991. More results published in 2000, 2004 and 2007. Eyetrack ’07: http://www.poynter.org/content/content_view. asp?id=105035 http://www.poynter.org/content/content_view. asp?id=105035

12. Research Communities ACM SIG/CHI Eye Tracking Research and Applications (ETRA) Symposium: http://www.e-t-r-a.org/http://www.e-t-r-a.org/ COGAIN: Communication by Gaze Interaction http://www.cogain.orghttp://www.cogain.org References: http://www.cogain.org/downloads/ http://www.cogain.org/downloads/

13. State-of-the-art Eye tracking Technology Hi-Speed (SMI iView X™ Hi-Speed) Head-Mounted System Remote tracking Integrated with LCD monitor

14. Mobile Eye Tracker@ NCCUCS eye camera scene camera

15. Key Objectives Low-cost (NTD 10,000 vs. 1,000,000) Mobility Easily customized for specific applications Sampling rate? On-line or off-line processing? Accuracy?

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

17. Pupil Detection (I): extracting feature points

18. Pupil Detection (II): Ellipse fitting using RANSAC

19. Pupil Detection (III): checking fitness measure Ellipse model: Number of bright vs. dark points inside and out the perimeter

20. Results

21. Another Approach Capture eye image using infrared camera Threshold-based method Pupil Iris

22. Illustrations

23. Calibration Process

24. Validation Procedure

25. Validation Results Starburst (pixels) Starburst + fitness check (pixels) Threshold-based (pixels) Subject 1182.17134.3838.51 Subject 2174.01118.9629.83 Subject 3207.36128.8685.2 Average error187.85127.451.18 *Resolution: 1024x768

26. HCI Application: Eye Scrolling

27. HCI Application: Eye Gaming

28. HCI Application: Eye Typing

29. Dynamic Scene

30. Gaze Path Analysis Recursive intersection Find the similarity between two scan paths Order of scanning is irrelevant Suitable for processing fixation data Modified dynamic time warping Order of scanning is taken into account Can handle both fixation and saccade data

31. Recursive Intersection Path 2 Path 1

32. Recursive Intersection: Example

33. Dynamic Time Warping (DTW)

34. Modified DTW (MDTW) X-axis Y-axis time

35. MDTW Result

36. Summary Low cost eye tracker construction Low cost ($10,000 NTD) Head-mount with mobile functionality HCI applications Sampling rate: depending on the camera’s frame rate Accuracy: suitable for some HCI applications, image viewing tasks, not high enough for reading. Gaze path analysis

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