1. Real-time parallax errorcompensation in head-mounted eye trackersDiako MardanbegiDan Witzner Hansen

2. Video-basedgaze trackersRemote gaze trackingHead-mounted gaze (RGT)tracking (HMGT) 3. Parallax error 4. A 5. [Valez et.al 1988 ] 6. Common method... All working planes are located on a finite set ofdistances Performing the calibration for each of these planes Recording the eye/scene image Using the appropriate calibration data for gazeestimation in each depth o Fine for offline gaze estimation o Fixation planes should be fronto-parallel 7. Method for online gaze estimationSeveral calibrations c1 c2 c3 c4 c5 Parameters of the mapping function 8. Measuring the depth Calibrated scene camera P1 x=[K]XP3 P2 Known size triangle Depth can be obtained for every point inside thefixation plane (Zmeasured) 9. c1c2 c3 c4 c5Zmeasured 10. c1 c2 c3 c4 c5 Zmeasured 11. Error behaviore (x, y)c 12. Error behaviore Zcerror0depthFitting a third degree polynomial to data points for nine points in the planes 13. Error estimation Compensating for parallax error knowing the errorbehaviorEye imageGaze estimation for (gx,gy)the calibration distance (ex,ey) (gx-ex,gy-ey)Scene imageZg 14. Calibration distance c error 0 depthThe shape of the error curve is the same when we choose another distanceas calibration distances. 15. Does the error pattern change between differentusers?o Angle between optical and visual axis of the eyeo Other eye properties Does the scene camera configuration change theerror pattern? 16. Thank youHaytham, Open source Head-mounted gaze tracker software http://itu.dk/research/eye/