Repository hosted by TU Delft Library

Home · Contact · About · Disclaimer ·
 

Determination of ocular torsion by means of automatic pattern recognition

Publication files not online:

Author: Groen, E.L. · Bos, J.E. · Nacken, P.F.M. · Graaf, B. de
Type:article
Date:1996
Institution: TNO Technische Menskunde
Source:IEEE Transactions on Biomedical Engineering, 5, 43, 471-479
Identifier: 8582
doi: doi:10.1109/10.488795
Keywords: Image processing · Algorithms · Automation · Biomechanics · Cameras · Charge coupled devices · Error correction · Estimation · Eye movements · Pattern recognition · Tissue · Torsional stress · Video signal processing · Human ocular torsion · Iris patterns · Otolith stimulation · Template matching · Torsion angles · Biomedical engineering · algorithm · article · eye · human · human experiment · iris · pattern recognition · rotation · torsion · Algorithms · Eye Movements · Humans · Image Processing, Computer-Assisted · Iris · Pattern Recognition, Visual · Pupil · Reproducibility of Results · Rotation · Videotape Recording

Abstract

A new, automatic method for determination of human ocular torsion (OT) was devel-oped based on the tracking of iris patterns in digitized video images. Instead of quanti-fying OT by means of cross-correlation of circular iris samples, a procedure commonly applied, this new method automatically selects and recovers a set of 36 significant patterns in the iris by the technique of template matching as described by In den Haak et al. [16]. Each relocated landmark results in a single estimate of the torsion angle. A robust algorithm estimates OT from this total set of individually determined torsion angles, hereby largely correcting for errors which may arise due to misjudgement of the rotation centre. The new method reproduced OT in a prepared set of images of an artificial eye with an accuracy of 0.1 deg. In a sample of 256 images of human eyes, a practical reliability of 0.25 deg. was achieved. To illustrate the method's usefulness, an experiment is described in which ocular torsion was measured during two dynamic conditions of whole-body roll, namely during sinusoidally pendular motion about either an earth horizontal or earth vertical axis (that is "with" and "without" otolith stimula-tion, respectively).