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Free Head Motion Eye Gaze Tracking Techniques

  • Carlos H. Morimoto
  • Flávio L. Coutinho
Part of the Signals and Commmunication Technologies book series (SCT)

Abstract

In this chapter we look at a passive eye monitoring system, or simply eye tracker (ET), as a mono-camera system that measures the position and orientation of the subject’s eye. The most common image based ET technique is known as the pupil-corneal reflection (PCR) technique, because it uses a reflection on the surface of the cornea (the first Purkinje image) generated by an external light source that is used as a “reference” point. The two dimensional image vector defined by the center of the pupil (or the iris) and the corneal reflection is used to estimate the gaze direction, after a simple calibration procedure that defines the mapping from image coordinates to screen coordinates1. To facilitate pupil detection and tracking in real-time, an active differential lighting scheme is commonly used [421]. By placing a light source near the camera optical center, a bright pupil image is generated, while a second light source, distant from the camera center, generates a dark pupil image. The two light sources can be synchronized with the video frame rate, so that at every other frame the camera captures a bright or a dark pupil image, and the pupil can be easily segmented as a high contrast region from the subtraction of the bright and dark pupil images.

Keywords

Cross Ratio Single Camera Point Light Source Virtual Point Pupil Center 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2008

Authors and Affiliations

  • Carlos H. Morimoto
    • 1
  • Flávio L. Coutinho
    • 1
  1. 1.Departement of Media and Image TechnologyUniversity of Sao PauloSao PauloBrazil

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