Accuracy and Precision of the Tobii X2-30 Eye-tracking under Non Ideal Conditions

Abstract

Abstract:This document describes a methodology for the measurement of accuracy and precision of a remote eye tracker, the Tobii X2-30, under non-ideal condition (without the use of a chinrest). The test was performed with 10 people (without disabilities). The results are: 2.46 and 1.91 degrees for the accuracy and precision respectively, while the device datasheet describe values of 0.40 and 0.26 degrees (accuracy and precision respectively). As expected, values calculated are higher, but they are better descriptors of the device's performance in conditions of normal use, where user can move the head freely. The results will be used to establish targets' size on the screen while the eye-tracker is used by people with cerebral palsy.

Eye-tracking for low vision with virtual reality (VR): testing status quo usability of the HTC Vive Pro Eye

“…For each sample data, we calculated the angle between the gaze direction vector (GD) and targeteye vector(TE) using the same formula (1) as Clemotte et al, 2014 to estimate the angle between two vectors (angleV).…”

“…For the analysis, we discarded the first 500 ms (Clemotte et al, 2014) after the target appearance that was considered as the time a subject used to direct the gaze towards it. In both conditions, we excluded from the analysis gaze points where no eye could be tracked both for the left and the right eye before averaging to avoid large errors in the mean's calculation.…”

“…Subjects performed the task in both conditions in a seated position on a chair. We randomized the target position, and we displayed the target for 5 seconds (Clemotte et al, 2014) with 5 repetitions (5 sec/target*25 targets*5 repetitions= 625 seconds, approximately 10 min and a half). In the head free condition, we added a central fixation target (coordinates: [0,0,0]) at the end of each target presentation that lasted 2 seconds.…”

Metodología de Evaluación de Eye-trackers como Dispositivos de Acceso Alternativo para Personas con Parálisis Cerebral

“…En un trabajo anterior (Clemotte, Velasco, Torricelli, Raya, & Ceres, 2014) estudiamos la precisión de un ET sin restricción de movimientos de la cabeza. Este trabajo se realizó con personas sin discapacidad, utilizando métricas de precisión y exactitud para medir la calidad de la interacción.…”

Development of Innovative HMI Strategies for Eye Controlled Wheelchairs in Virtual Reality

“…Among them illumination, relative motion between the user and the instrument (rotation and translation), objects in front of the eyes, physiology of the different users [4]. Another problem underlined from many authors is that the performances provided by the manufacturers seems to be neither repeatable not representative as they are obtained in ideal conditions [9].…”