1. Practical Gaze Tracking Peter Elliott CS 498 Spring 2009

2. Outline What is gaze tracking Methods How does it work Current problems Applications Questions

3. Gaze Tracking Determine what a person is looking at Human-computer interaction Practical? –Need unobtrusive hardware –Don’t overload the eyes

4. Sclera Coil Contact lens with Copper wire Uses changes in magnetic field http://www.skalar.nl/graphics/fig1.jpg

5. Sclera Coil http://mvl.mit.edu/Neurovestibular/Pictures/Shelhamer/EyeCoilNear.jpg

6. Electro-oculographic Potential Electrodes placed on face Measures electric charge of the eye http://www.sciencedaily.com/images/2008/04/080428083418.jpg

7. Fixed Head Position Similar to current technique Requires headrest http://upload.wikimedia.org/wikipedia/en/f/f4/ SMI_HiSpeed_EyeTracker.jpg

8. Finding Gaze Position Requires special hardware –Camera and two point light sources (IR) Reflections of light stay stationary on the eye

9. Glints http://www.innerhealthandbeauty.net/images/Mixed_Iris.JPG

10. Finding Gaze Position Use image processing to extract ellipses of pupil and glints Determine 3D position of the eye Use geometry to map to screen coordinates Calibration

11. Problems Special hardware Eye movements Accuracy Natural feel

12. Hardware http://www.tobii.com/Images/contentimages/Produ ktbilder/tobii-t60-eye-tracker-perspective.jpg http://www.ecse.rpi.edu/~cvrl/zhiwei/gazetracking/SystemView.jpg

13. Eye Movements Not smooth Fixations and saccades Eye jitters http://upload.wikimedia.org/wikipedia/en/b/b9/Re adingFixationsSaccades.jpg

14. Accuracy 16-33 pixels ~30ms response time

15. Natural Feel Don’t want to overload eyes Sensors, not used for motor control Must feel “natural” Users must feel free Hardware can only go so far, need software

16. Applications Market research Surgeons/Doctors Disabled users Able-bodied users –Future method of human-computer interaction?

17. Marketing Application – Heat Maps http://www.tobii.com/Images/contentimages/pageImages/Mag_spread_Heat_map.jpg

18. Summary How gaze position is found New form of human-computer interaction Current solutions relatively unobtrusive Not without problems –Cost –Accuracy

19. Questions?