Measurement of torsional eye movement by spatial moments of iris pattern image

Abstract

We propose a torsional eye movement measurement method based on the spatial moment analysis of iris pattern image. First the measurement procedure is proposed. Then our proposed method was evaluated by applying it to an eye movement image sequence simulated by our developed three-dimensional eye movement simulator. The results measured by the spatial moment analysis and the method based on stochastic algorithms show that the standard deviation of torsion angle errors for the spatial moment analysis is less than that for the method based on stochastic algorithms. Next, we applied it to an image sequence obtained with the infrared CCD camera. For the comparison, the torsion angles were measured by using the methods based on stochastic algorithms and the cross correlation analysis. The technique based on cross correlation of a sampled iris pattern encircling the pupil is well used in the torsion angle measurement. The results measured by three methods show similarity but the result for the moment analysis resembles that for the cross correlation analysis more closely than that for the method based on stochastic algorithms. The differences between them were around 1degree. From the computational complexity, our proposed spatial moment analysis method becomes a simple torsion angle measurement.