A Simple Device to Measure Gaze Angles in Visual Task Analyses

Abstract

This paper presents a simple device to measure visual maps and head motion to analyze the visual strategy in optometric applications. Instead of using the common approach of conventional eye trackers based on continuous pupil–corneal reflection detection, a simple method based on photogrammetry is proposed. This method only measures the head movements, the gaze direction and the visual map can be calculated on the hypothesis that subjects’ gaze follows a known visual stimulus accurately. In order to validate this hypothesis, an experiment has been carried out to calculate the subject’s accuracy when tracking the stimulus. The gaze direction was measured both with conventional eye tracking and with the proposed technique and the measured gaze angles were compared. The results show that the subjects effectively follow the stimulus during the task and thus the main hypothesis of the proposed system is confirmed. Therefore, the analysis of head movement can supply an indirect estimation of the visual angles that is as accurate as the measures obtained with more complex devices.