A novel method for measuring gaze orientation in space in unrestrained head conditions

Benedetta Cesqui, Rolf van De Langenberg, Francesco Lacquaniti, Andrea d'Avella

Research output: Contribution to journalArticlepeer-review


Investigation of eye movement strategies often requires the measurement of gaze orientation without restraining the head. However, most commercial eye-trackers have low tolerance for head movements. Here we present a novel geometry-based method to estimate gaze orientation in space in unrestricted head conditions. The method combines the measurement of eye-in-head orientation-provided by a head-mounted video-based eye-tracker-and head-in-space position and orientation-provided by a motion capture system. The method does not rely on specific assumptions on the configuration of the eye-tracker camera with respect to the eye and uses a central projection to estimate the pupil position from the camera image, thus improving upon previously proposed geometry-based procedures. The geometrical parameters for the mapping between pupil image and gaze orientation are derived with a calibration procedure based on nonlinear constrained optimization. Additionally, the method includes a procedure to correct for possible slippages of the tracker helmet based on a geometricalrepresentation of the pupil-to-gaze mapping. We tested and validated our method on seven subjects in the context of a onehanded catching experiment. We obtained accuracy better than 0.88 and precision better than 0.5° in the measurement of gaze orientation. Our method can be used with any video-based eye-tracking system to investigate eye movement strategies in a broad range of naturalistic experimental scenarios.

Original languageEnglish
Article number28
JournalJournal of Vision
Issue number8
Publication statusPublished - 2013


  • Calibration
  • Drift correction
  • Gaze orientation in space
  • Nonlinear optimization
  • Oculography

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems


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