A cost function to determine the optimum filter and parameters for stabilizing gaze data

Prior to delivery of data, eye tracker software may apply filtering to correct for noise. Although filtering produces much better precision of data, it may add to the time it takes for the reporting of gaze data to stabilise after a saccade due to the usage of a sliding window. The effect of various filters and parameter settings on accuracy, precision and filter related latency is examined. A cost function can be used to obtain the optimal parameters (filter, length of window, metric and threshold for removal of samples and removal percentage). It was found that for any of the FIR filters, the standard deviation of samples can be used to remove 95% of samples in the window so than an optimum combination of filter related latency and precision can be obtained. It was also confirmed that for unfiltered data, the shape of noise, signified by RMS/STD, is around √2 as expected for white noise, whereas lower RMS/STD values were observed for all filters

ZASTOSOWANIA ANALIZY RUCHU OCZU W DIAGNOSTYCE CHORÓB NEURODEGENERACYJNYCH

Eye-tracking allows for non-invasive examination and the same eyetrackers are becoming more available, thus its popularity in medical diagnosis and other fields of application is increasing. The paper presents the possibilities for using eye-tracking in the diagnosis neurodegenerative disease such as Parkinson or Alzheimer diseases. The autor describes the exetracking experiment, the model of fixations and saccedes detection, as well as the selected examples of eye-tracking research conducted among patients with neurodegenerative diseases.Badania okulograficzne są nieinwazyjne, a sprzęt okulograficzny coraz bardziej dostępny, dlatego też rośnie jego popularność w diagnostyce medycznej oraz innych obszarach zastosowań. Artykuł prezentuje możliwości dotyczący zastosowania badań okulograficznych w diagnostyce chorób neurodegeneracyjnych takich jak Parkinson, czy Alzheimer. Autorka koncentruje się na przestawieniu charakterystyki badania okulograficznego, modelu detekcji podstawowych zdarzeń takich jak fiksacje i sakkady, a także na przykładach badań zaburzeń okoruchowych w wybranych chorobach neurodegeneracyjnych

Probabilistic Approach to Robust Wearable Gaze Tracking

Creative Commons Attribution License (CC BY 4.0)This paper presents a method for computing the gaze point using camera data captured with a wearable gaze tracking device. The method utilizes a physical model of the human eye, ad- vanced Bayesian computer vision algorithms, and Kalman filtering, resulting in high accuracy and low noise. Our C++ implementation can process camera streams with 30 frames per second in realtime. The performance of the system is validated in an exhaustive experimental setup with 19 participants, using a self-made device. Due to the used eye model and binocular cam- eras, the system is accurate for all distances and invariant to device movement. We also test our system against a best-in-class commercial device which is outperformed for spatial accuracy and precision. The software and hardware instructions as well as the experimental data are pub- lished as open source.Peer reviewe

An informatics system for exploring eye movements in reading

Eye tracking techniques have been widely used in many research areas including cognitive science, psychology, human-computer interaction, marketing research, medical research etc. Many computer programs have emerged to help these researchers to design experiments, present visual stimuli and process the large quantity of numerical data produced by the eye tracker. However, most applications, especially commercial products, are designed for a particular tracking device and tend to be general purpose. Few of them are designed specifically for reading research. This can be inconvenient when dealing with complex experimental design, multi-source data collection, and text based data analysis, including almost every aspect of a reading study lifecycle. A flexible and powerful system that manages the lifecycle of different reading studies is required to fulfill these demands. Therefore, we created an informatics system with two major software suites: Experiment Executor and EyeMap. It is a system designed specifically for reading research. Experiment Executor helps reading researchers build complex experimental environments, which can rapidly present display changes and support the co-registration of eye tracking information with other data collection devices such as EEG (electroencephalography) amplifiers. The EyeMap component helps researchers visualize and analysis a wide range of writing systems including spaced and unspaced scripts, which can be presented in proportional or non-proportional font types. The aim of the system is to accelerate the life cycle of a reading experiment from design through analysis. Several experiments were conducted on this system. These experiments confirmed the effectiveness and the capability of the system with several new reading research findings from the visual information processing stages of reading

Event Detection in Eye-Tracking Data for Use in Applications with Dynamic Stimuli

This doctoral thesis has signal processing of eye-tracking data as its main theme. An eye-tracker is a tool used for estimation of the point where one is looking. Automatic algorithms for classification of different types of eye movements, so called events, form the basis for relating the eye-tracking data to cognitive processes during, e.g., reading a text or watching a movie. The problems with the algorithms available today are that there are few algorithms that can handle detection of events during dynamic stimuli and that there is no standardized procedure for how to evaluate the algorithms. This thesis comprises an introduction and four papers describing methods for detection of the most common types of eye movements in eye-tracking data and strategies for evaluation of such methods. The most common types of eye movements are fixations, saccades, and smooth pursuit movements. In addition to these eye movements, the event post-saccadic oscillations, (PSO), is considered. The eye-tracking data in this thesis are recorded using both high- and low-speed eye-trackers. The first paper presents a method for detection of saccades and PSO. The saccades are detected using the acceleration signal and three specialized criteria based on directional information. In order to detect PSO, the interval after each saccade is modeled and the parameters of the model are used to determine whether PSO are present or not. The algorithm was evaluated by comparing the detection results to manual annotations and to the detection results of the most recent PSO detection algorithm. The results show that the algorithm is in good agreement with annotations, and has better performance than the compared algorithm. In the second paper, a method for separation of fixations and smooth pursuit movements is proposed. In the intervals between the detected saccades/PSO, the algorithm uses different spatial scales of the position signal in order to separate between the two types of eye movements. The algorithm is evaluated by computing five different performance measures, showing both general and detailed aspects of the discrimination performance. The performance of the algorithm is compared to the performance of a velocity and dispersion based algorithm, (I-VDT), to the performance of an algorithm based on principle component analysis, (I-PCA), and to manual annotations by two experts. The results show that the proposed algorithm performs considerably better than the compared algorithms. In the third paper, a method based on eye-tracking signals from both eyes is proposed for improved separation of fixations and smooth pursuit movements. The method utilizes directional clustering of the eye-tracking signals in combination with binary filters taking both temporal and spatial aspects of the eye-tracking signal into account. The performance of the method is evaluated using a novel evaluation strategy based on automatically detected moving objects in the video stimuli. The results show that the use of binocular information for separation of fixations and smooth pursuit movements is advantageous in static stimuli, without impairing the algorithm's ability to detect smooth pursuit movements in video and moving dot stimuli. The three first papers in this thesis are based on eye-tracking signals recorded using a stationary eye-tracker, while the fourth paper uses eye-tracking signals recorded using a mobile eye-tracker. In mobile eye-tracking, the user is allowed to move the head and the body, which affects the recorded data. In the fourth paper, a method for compensation of head movements using an inertial measurement unit, (IMU), combined with an event detector for lower sampling rate data is proposed. The event detection is performed by combining information from the eye-tracking signals with information about objects extracted from the scene video of the mobile eye-tracker. The results show that by introducing head movement compensation and information about detected objects in the scene video in the event detector, improved classification can be achieved. In summary, this thesis proposes an entire methodological framework for robust event detection which performs better than previous methods when analyzing eye-tracking signals recorded during dynamic stimuli, and also provides a methodology for performance evaluation of event detection algorithms

Multikamerabasiertes Verfahren zur Fokusebenenbestimmung für eine AR-Datenbrille mit adaptiver Optik

Logistikmitarbeiter können mit Augmented-Reality-Datenbrillen ausgerüstet werden, um relevante Daten in ihr Sichtfeld einblenden zu lassen. Mithilfe moderner Datenbrillen können Visualisierungen dabei aufgrund der Brennweitendifferenz zwischen dem menschlichen Auge und der Datenbrillenoptik meist nur auf definierte Entfernungen scharf dargestellt werden. Ein Angleich der Brennweite der Optik an die Brennweite des Auges ermöglicht eine scharfe Darstellung der Inhalte innerhalb des Griffbereiches des Mitarbeiters. Zur Realisierung dieses Ansatzes wird in dieser Arbeit ein multikamerabasiertes Verfahren zur automatischen Adaptierung der Optikbrennweite vorgeschlagen. Für die Brennweitenadaptierung wird ein Ansatz zur Pupillendetektion in Kombination mit einer 3D-Umgebungskamera vorgestellt. Da geläufige Algorithmen zur Pupillendetektion nicht für die Verwendung auf eingebetteten Systemen optimiert sind, wird der Schwerpunkt auf die Entwicklung eines geeigneten ressourcenarmen Algorithmus gelegt. Die nötige Relation zwischen dem menschlichen Auge und der 3D-Kamera wird dabei über einen Ansatz der mehrstufigen Ebenenkalibrierung realisiert. Die gewonnenen 3D-Tiefeninformationen werden anschließend mithilfe einer adaptiven Flüssiglinse zur Brennweitenjustierung der Optik genutzt. Da aktuell keine Datenbrillen mit den genannten Komponenten erhältlich sind, wurde eine eigenes Konzept realisiert. Die später beabsichtigte Anwendung soll dem Nutzer dabei Informationen zur Umsetzung aktueller Aufgaben anzeigen und diese direkt auf die Brennweite des Auges anpassen, um dessen kognitive Belastung zu reduzieren.:1 Einleitung 1 1.1 Aktueller Stand der Technik 2 1.2 Systemübersicht 6 1.3 Inhaltliche Gliederung 8 1.4 Wissenschaftlicher Beitrag 9 2 Theoretische Vorbetrachtungen 11 2.1 Augmentierte Realität 11 2.1.1 Übersicht 11 2.1.2 Videoaufnahme in Echtzeit 13 2.1.3 Tracking 13 2.1.4 Registrierung 15 2.1.5 Visuelle Ausgabemöglichkeiten 16 2.1.6 Eye-Tracking in AR 17 2.2 Das menschliche Auge 18 2.2.1 Anatomie 19 2.2.2 Das Auge als dioptrischer Apparat 22 2.2.3 Die Pupille 25 2.2.4 Verhaltensanalyse des Auges 26 2.2.5 Die retinale Signalverarbeitung 27 2.3 3D-Umgebungen 29 2.3.1 Kameramodell 29 2.3.2 Stereoskopie 32 2.3.3 Strukturiertes Licht 37 2.3.4 Time of Flight 39 3 Entwurf einer AR-Datenbrille mit blickpunktabhängiger Brennweitenadaptierung 42 3.1 Gesamtsystem 42 3.2 Infrarotbeleuchtung für die Eye-Tracking-Kamera 44 3.2.1 Gefährdung der Kornea durch IR-A Strahlen 47 3.2.2 Thermische Netzhautgefährdung – schwacher visueller Reiz 48 3.2.3 Überprüfung der Einhaltung der Grenzwerte der selektierten IR-LED 50 3.3 Optisches System 53 3.4 Adaptive Linse 55 3.5 3D-Umgebungskamera 56 3.6 Recheneinheit 58 4 Eye-Tracking 59 4.1 Einleitung 59 4.2 Voruntersuchungen 64 4.3 Eye-Tracking-Algorithmus „Fast Ellipse Fitting “(FEF) 67 4.3.1 Stand der Forschung 67 4.3.2 Übersicht 69 4.3.3 Schwellwertapproximation 70 4.3.4 ROI-Findung / hochaufgelöste Schwellwertsuche 72 4.3.5 Pupillendetektion 75 4.3.6 Anfälligkeiten 76 4.4 Validierung 81 4.5 Zusammenfassung 85 4.6 Diskussion 86 5 Blickpunktschätzung 87 5.1 Einleitung 87 5.2 2D-Blickpunktschätzung 89 5.2.1 Einleitung 89 5.2.2 Evaluierung 92 5.3 3D-Blickpunktschätzung 100 5.3.1 Stand der Technik 100 5.3.2 Aufnahme von Kalibrierungspunkten im 3D-Raum 103 5.3.3 Algorithmen zur 3D-Blickpunktschätzung 104 5.3.4 Evaluierung 108 5.4 Zusammenfassung 111 5.5 Diskussion 111 6 Blickpunktanalyse 113 6.1 Filterung der Augenbewegungen/Glint-Vektoren 113 6.1.1 Stand der Forschung 113 6.1.2 Glättung der Glint-Vektoren 116 6.2 Blickpunktauswertung 117 6.2.1 Display-Steuerung 119 6.2.2 Eye-Tracking zur Informationsergänzung 125 6.2.3 Validierung der 3D-Blickpunktschätzung 131 6.3 Zusammenfassung 135 6.4 Diskussion 136 7 Zusammenfassung 138 8 Ausblick 140 9 Literaturverzeichnis 142 A Anhang 15

Noise Challenges in Monomodal Gaze Interaction

Modern graphical user interfaces (GUIs) are designed with able-bodied users in mind. Operating these interfaces can be impossible for some users who are unable to control the conventional mouse and keyboard. An eye tracking system offers possibilities for independent use and improved quality of life via dedicated interface tools especially tailored to the users ’ needs (e.g., interaction, communication, e-mailing, web browsing and entertainment). Much effort has been put towards robustness, accuracy and precision of modern eyetracking systems and there are many available on the market. Even though gaze tracking technologies have undergone dramatic improvements over the past years, the systems are still very imprecise. This thesis deals with current challenges of mono-modal gaze interaction and aims at improving access to technology and interface control for users who are limited to the eyes only. Low-cost equipment in eye tracking contributes toward improved affordability but potentially at the cost of introducing more noise in the system due to the lower quality of hardware. This implies that methods of dealing with noise and creative approaches towards getting the best out of the data stream are most wanted. The work in this thesis presents three contributions that may advance the use of low-cost mono-modal gaze tracking and research in the field:- An assessment of a low-cost open-source gaze tracker and two eye tracking systems through an accuracy and precision test and a performance evaluation.- Development and evaluation of a novel innovative 3D typing system with high tolerance to noise that is based on continuous panning and zooming.- Development and evaluation of novel selection tools that compensate for noisy input during small-target selections in modern GUIs. This thesis may be of particular interest for those working on the use of eye trackers for gaze interaction and how to deal with reduced data quality. The work in this thesis is accompanied by several software applications developed for the research projects that can be freely downloaded from the eyeInteract appstore 1