SET: a pupil detection method using sinusoidal approximation.
Mobile eye-tracking in external environments remains challenging, despite recent advances in eye-tracking software and hardware engineering. Many current methods fail to deal with the vast range of outdoor lighting conditions and the speed at which these can change. This confines experiments to artificial environments where conditions must be tightly controlled. Additionally, the emergence of low-cost eye tracking devices calls for the development of analysis tools that enable non-technical researchers to process the output of their images. We have developed a fast and accurate method (known as "SET") that is suitable even for natural environments with uncontrolled, dynamic and even extreme lighting conditions. We compared the performance of SET with that of two open-source alternatives by processing two collections of eye images: images of natural outdoor scenes with extreme lighting variations ("Natural"); and images of less challenging indoor scenes ("CASIA-Iris-Thousand"). We show that SET excelled in outdoor conditions and was faster, without significant loss of accuracy, indoors. SET offers a low cost eye-tracking solution, delivering high performance even in challenging outdoor environments. It is offered through an open-source MATLAB toolkit as well as a dynamic-link library ("DLL"), which can be imported into many programming languages including C# and Visual Basic in Windows OS (www.eyegoeyetracker.co.uk).
Department of Experimental Psychology, Institute of Behavioural Neuroscience University College London London, UK.
Amir-Homayoun
AH
Javadi
Young Researchers and Elite Club, Qazvin Branch, Islamic Azad University Qazvin, Iran.
Zahra
Z
Hakimi
Young Researchers and Elite Club, Qazvin Branch, Islamic Azad University Qazvin, Iran.
Morteza
M
Barati
Institute of Cognitive Neuroscience, University College London London, UK.
Vincent
V
Walsh
Institute of Cognitive Neuroscience, University College London London, UK.
Lili
L
Tcheang
dark pupil; ellipse fitting; eye tracking; head mounted device; pupil detection