Eye Tracker accuracy and precision

a researcher's Eye movement tracking scheme: Yuta Itoh (Shito)

(Http://campar.in.tum.de/Main/YutaItoh Fellow at the Chair for Computer aided medical Procedures & augmented Reality, Munich, Germany

Http://www.ar.c.titech.ac.jp/cpt_people/yuta-itoh/principal Investigator of augmented Vision Lab East Industrial University, School of Technology

Close range, high accuracy, reflective image method, eyeball attitude detection Conference on Human Factors in Computing Systems 2017:

Toward everyday gaze input:accuracy and Precision of Eye tracking and implications for design (2017)

(https://dl.acm.org/citation.cfm?id=3025599)

Very good Practical survey paper, introduces the evaluation method of visual tracking accuracy Tobii:Eye tracker accuracy and precision

(https://www.tobiipro.com/learn-and-support/learn/eye-tracking-essentials/ what-affects-the-accuracy-and-precision-of-an-eye-tracker/)

Accuracy and precision are important concepts for understanding I-eye tracker, and how can one performs T He quality the recorded eye tracking data.

During data collection, accuracy and precision are used as indicators of the eye tracker data validity. A system with good accuracy and precision'll provide more valid data as it's able to truthfully describe the location O f a person ' s gaze on a screen. The accuracy is defined as the average difference between the real stimuli position and the measured gaze. Precision is defined as the ability of the eye tracker to reliably reproduce the same gaze point measurement, i.e. it Measu Res The variation of the recorded data via the Root Mean Square (RMS) of successive samples. the required level of AC Curacy and precision depends on the "the" Eye tracking study. Small uncertainties, for instance, can is critical when analyzing gaze data in reading studies/studies with a Small STI mulus. 

The accuracy error varies considerably across participants and experimental conditions. Accuracy is dependent on participant properties, illumination in the test environment, stimuli properties, calibration qua lity, data collection procedure and the eyes ' position in the track box.

Impact of large accuracy & precision errors

Aga Bojko ' s Blog: The Most Precise (or Most accurate?) Eye Tracker

(https://blog.gfk.com/2011/05/the-most-precise-or-most-accurate-eye-tracker/)

(Re-post from the "Eye tracking the User experience" Blog. The Aga is currently writing Eye tracking the User experience, A practical Guide, to being published by Rosenfeld Media in 2013.)

To keep and technology, I have a Google Alert set up for "eye tracking" OR "Eyetracki Ng "OR" eye-tracking. " The daily email comes to my Inbox at 11:30am, just in time for my browsing lunch (more fun than a working lunch, less fun than a non-working lunch). Today, nine out of the twenty results in the alert email mentioned Tobii Technology introducing the "most precise the TRAC King solution for mobile device testing:

Most precise! Who could resist that?

The solution (Tobii Mobile Device stand) described in the articles is actually quite. I ' m Not sure why it made the news today because it's been for a while now. Maybe It is just this morning when they found it is "most precise." I continued reading in suspense.

To my disappointment, no explanation is offered for the this conclusion is reached. What ' s more, I don ' t even know What is meant by "precise." I am the author is referring to the accuracy of the eye tracking solution I can ' t be but. And that's precisely where the problem lies–in the confusion between precision and accuracy (and people not realizing th At there is confusion). Let me explain ...

The accuracy of eye tracker is the average difference between what the eye tracker as the recorded gaze and position At the gaze position actually is. We want this offset to being as small as possible but it is obviously unrealistic to expect it to being equal to zero.

Accuracy is measured in degrees of visual angle. Typical accuracy values fall in a range between 0.5 and 1 degree. To give your idea of the what that means, one degree corresponds to half a inch (1.2 cm) on a computer monitor viewed at a Distance of inches (68.6 cm). In the other words, the actual gaze location could is anywhere within a radius of 0.5 inch (the blue circle below) from the GA Ze location recorded with a eye tracker with one degree of accuracy (the "X"):

accuracy values reported in eye tra Cker manuals are measured under ideal, conditions which include, for typically, example testing with no participants Ctive Eyewear and taking the measurement immediately after calibration. During "Real," the difference between the reported and actual gaze locations can is larger for participants Weari NG glasses or contacts lenses or those who moved in some point following the calibration.

Precision (aka "Spatial Resolution"), on the ' The other hand ', is a measure ' how, ' eye tracker is able to reliably repr Oduce a measurement. Ideally, if the eye is in the same exact location in two, successive measurements, the eye tracker the should Cations as identical. That would is perfect precision.

In reality, precision values of currently available eye trackers range from 0.01 to 1 degree. These values are calculated as the root mean square of the distance (in degrees of visual angle) between successive sample S. Because the precision values reported by manufacturers are measured using a motionless artificial eye (pretty-cool, huh ?), tracking real eyes would exhibit less precision.

The table below summarizes the relationship between eye tracking accuracy and precision. The cross indicates the actual gaze location, while the "dots are gaze" locations reported by the eye.

All in all, the ' most precise eye tracking solution ' was probably just a poor choice of words but it gave me ' excuse to Talk about precision vs. accuracy and sound like I ' m up to date on the current events. I do what I can.

Tristan Hume ' s : Eye Tracker Reviews:pupil, Labs, Tobii Eye, tribe

(http://thume.ca/2016/03/24/eye-tracker-reviews-pupil-labs-tobii-eyex-eye-tribe-tobii-x2-30/)