Article - This Is How Eye Tracking Technology Works

  • Metadata:
    • author: A. Mark Mento
    • title: This Is How Eye Tracking Technology Works
    • url: Weblink
  • The first part of eye-tracking (IR based) systems is pupil detection, which is done using one of two systems
    • Bright pupil systems use an IR source that is on the same axis as the IR camera, illuminating the pupil. Works best in dimly lit rooms, infants with not fully developed pigments and subjects with pale blue eyes.
    • Dark pupil eye tracking systems use an IR source that is off axis from the kamera and lights up everything except the pupil (then looking for a dark spot). This method is more robust for dark eyed individuals and under varying light conditions.
  • In both cases, the cornea reflection (bright spot from illumination off the spherical surface) is also tracked, which is used to determine if the head is turned or not moved.
  • Before calibration: (gaze position) = (pupil position) - (CR position) (postition: coordinate on the video feed)
  • During calibration, a regression is performed to learn the relationship between gaze position and screen position
  • ==Idea: measure the accuracy of calibration and redo the calibration if the accuracy is below a certain threshold. This could be difficult with children though==