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Real-time parallax errorcompensation in head-mounted         eye trackers        Diako Mardanbegi        Dan Witzner Hansen
Video-based                  gaze trackersRemote gaze tracking            Head-mounted gaze       (RGT)                   ...
Parallax error
A’
[Valez et.al 1988 ]
Common method...• All working planes are located on a finite set of  distances• Performing the calibration for each of the...
Method for online gaze estimationSeveral calibrations                               c1     c2   c3   c4   c5              ...
Measuring the depth• Calibrated scene camera                                   P1             x=[K]X          P3         P...
c1        c2   c3   c4   c5Zmeasured
c1   c2   c3     c4   c5     Zmeasured
Error behaviore µ(x, y)                  c
Error behaviore µZ                                      c                error    0                                      d...
Error estimation  • Compensating for parallax error knowing the error    behaviorEye image                Gaze estimation ...
Calibration distance                           c               error   0                                   depthThe shape ...
• Does the error pattern change between different  users?  o Angle between optical and visual axis of the eye  o Other eye...
Thank youHaytham, Open source Head-mounted gaze tracker software               http://itu.dk/research/eye/
Real-time parallax error compensation in head-mounted eye trackers
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Real-time parallax error compensation in head-mounted eye trackers

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Scandinavian Workshop on Applied Eye Tracking SWAET 2012

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Real-time parallax error compensation in head-mounted eye trackers

  1. 1. Real-time parallax errorcompensation in head-mounted eye trackers Diako Mardanbegi Dan Witzner Hansen
  2. 2. Video-based gaze trackersRemote gaze tracking Head-mounted gaze (RGT) tracking (HMGT)
  3. 3. Parallax error
  4. 4. A’
  5. 5. [Valez et.al 1988 ]
  6. 6. Common method...• All working planes are located on a finite set of distances• Performing the calibration for each of these planes• Recording the eye/scene image• Using the appropriate calibration data for gaze estimation in each depth o Fine for offline gaze estimation o Fixation planes should be fronto-parallel
  7. 7. Method for online gaze estimationSeveral calibrations c1 c2 c3 c4 c5 Parameters of the mapping function
  8. 8. Measuring the depth• Calibrated scene camera P1 x=[K]X P3 P2 Known size triangle• Depth can be obtained for every point inside the fixation plane (Zmeasured)
  9. 9. c1 c2 c3 c4 c5Zmeasured
  10. 10. c1 c2 c3 c4 c5 Zmeasured
  11. 11. Error behaviore µ(x, y) c
  12. 12. Error behaviore µZ c error 0 depthFitting a third degree polynomial to data points for nine points in the planes
  13. 13. Error estimation • Compensating for parallax error knowing the error behaviorEye image Gaze estimation for (gx,gy) the calibration distance (ex,ey) (gx-ex,gy-ey)Scene image Zg
  14. 14. Calibration distance c error 0 depthThe shape of the error curve is the same when we choose another distanceas calibration distances.
  15. 15. • Does the error pattern change between different users? o Angle between optical and visual axis of the eye o Other eye properties• Does the scene camera configuration change the error pattern?
  16. 16. Thank youHaytham, Open source Head-mounted gaze tracker software http://itu.dk/research/eye/

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