Echtzeitblickrichtungserfassung mit CMOS-Zweikamerasystem

Es wurde ein Eyetracking-Konzept entworfen, welches sich sich auf die VOG unter Verwendung eines Zweikamerasystems und spezieller Bildverarbeitungs und SD-Algorithmen stützt. Entwickelt wurde ein Versuchsaufbau, bestehend aus einem Zweikamerasystem, IRBeleuchtung und einem dreh- und verschiebbar gelagerten Augenmodell. Der Algorithmus zur Berechnung der Lage des Messobjektes wurde für den Echtzeitbetrieb auf PCTechnik optimiert. Messergebnisse am Augenmodell zeigen, dass die angestrebten Genauigkeit s- und Geschwindigkeitsanforderungen erfüllt werden. Das wichtigste Ergebnis der Messungen ist die Tatsache, dass die räumliche Lage eines pupillenähnlichen Messobjektes ohne vorherige Kalibration ermittelt werden kann. Weiterführende Untersuchungen müssen zeigen, ob dies auch für Messungen am menschlichen Auge gilt

The Effect of Real-time Headbox Adjustments on Data Quality

Following a patent owned by Tobii, the framerate of a CMOS camera can be increased by reducing the size of the recording window so that it fits the eyes with minimum room to spare. The position of the recording window can be dynamically adjusted within the camera sensor area to follow the eyes as the participant moves the head. Since only a portion of the camera sensor data is communicated to the computer and processed, much higher framerates can be achieved with the same CPU and camera.Eye trackers can be expected to present data at a high speed, with good accuracy and precision, small latency and with minimal loss of data while allowing participants to behave as normally as possible. In this study, the effect of headbox adjustments in real-time is investigated with respect to the above-mentioned parameters.It was found that, for the specific camera model and tracking algorithm, one or two headbox adjustments per second, as would normally be the case during recording of human participants, could be tolerated in favour of a higher framerate. The effect of adjustment of the recording window can be reduced by using a larger recording window at the cost of the framerate

Fuzzy Mouse Cursor Control System for Computer Users with Spinal Cord Injuries

People with severe motor-impairments due to Spinal Cord Injury (SCI) or Spinal Cord Dysfunction (SCD), often experience difficulty with accurate and efficient control of pointing devices (Keates et al., 02). Usually this leads to their limited integration to society as well as limited unassisted control over the environment. The questions “How can someone with severe motor-impairments perform mouse pointer control as accurately and efficiently as an able-bodied person?” and “How can these interactions be advanced through use of Computational Intelligence (CI)?” are the driving forces behind the research described in this paper. Through this research, a novel fuzzy mouse cursor control system (FMCCS) is developed. The goal of this system is to simplify and improve efficiency of cursor control and its interactions on the computer screen by applying fuzzy logic in its decision-making to make disabled Internet users use the networked computer conveniently and easily. The FMCCS core consists of several fuzzy control functions, which define different user interactions with the system. The development of novel cursor control system is based on utilization of motor functions that are still available to most complete paraplegics, having capability of limited vision and breathing control. One of the biggest obstacles of developing human computer interfaces for disabled people focusing primarily on eyesight and breath control is user’s limited strength, stamina, and reaction time. Within the FMCCS developed in this research, these limitations are minimized through the use of a novel pneumatic input device and intelligent control algorithms for soft data analysis, fuzzy logic and user feedback assistance during operation. The new system is developed using a reliable and cheap sensory system and available computing techniques. Initial experiments with healthy and SCI subjects have clearly demonstrated benefits and promising performance of the new system: the FMCCS is accessible for people with severe SCI; it is adaptable to user specific capabilities and wishes; it is easy to learn and operate; point-to-point movement is responsive, precise and fast. The integrated sophisticated interaction features, good movement control without strain and clinical risks, as well the fact that quadriplegics, whose breathing is assisted by a respirator machine, still possess enough control to use the new system with ease, provide a promising framework for future FMCCS applications. The most motivating leverage for further FMCCS development is however, the positive feedback from persons who tested the first system prototype

A Review and Analysis of Eye-Gaze Estimation Systems, Algorithms and Performance Evaluation Methods in Consumer Platforms

In this paper a review is presented of the research on eye gaze estimation techniques and applications, that has progressed in diverse ways over the past two decades. Several generic eye gaze use-cases are identified: desktop, TV, head-mounted, automotive and handheld devices. Analysis of the literature leads to the identification of several platform specific factors that influence gaze tracking accuracy. A key outcome from this review is the realization of a need to develop standardized methodologies for performance evaluation of gaze tracking systems and achieve consistency in their specification and comparative evaluation. To address this need, the concept of a methodological framework for practical evaluation of different gaze tracking systems is proposed.Comment: 25 pages, 13 figures, Accepted for publication in IEEE Access in July 201

Blickbasierte Interaktion mit 3D-Displays : Entwicklung eines Prototyps zur Evaluierung blickbasierter Interaktion

Maus und Tastatur sind die Eingabegeräte am Computer schlechthin. Doch es gibt noch eine Reihe weiterer Methoden, wie Menschen mit Computern interagieren können. In dieser Arbeit sollen blickbasierte Interaktionsmethoden auf 3D-Bildschirmen untersucht werden. Mithilfe eines Eyetrackers und eines 3D-Bildschirms sollen von einer Beispielapplikation bereitgestellte Aufgaben gelöst und die Performanz der unterschiedlichen Lösungsansätze gemessen und diskutiert werden. Das Konzept, die Entwicklung der Applikation, die durchgeführte Studie und die dazugehörige Evaluierung werden in dieser Arbeit besprochen. Zuletzt werden Ansätze vorgestellt, welche in Zukunft die Leistung solcher Systeme möglicherweise noch erhöhen könnten.The mouse and the keyboard are traditionally used as input devices. However, there are more methods how people can interact with computers. In this thesis, methods for gaze based interaction with 3D displays are investigated. Utilizing an eye tracker and a stereoscopic display, different tasks should be solved and the performance of the interaction methods within a prototypical application is measured. The concept, the development of the prototyp, and the evaluation are part of this thesis. Finally, some approaches are discussed that could improve the performace of such systems in the future

Unterschwellige Lenkung der Benutzeraufmerksamkeit in grafischen Programmoberflächen

In den 1950er Jahren wurden, laut einer Pressemitteilung, unterschwellige Werbemethoden zur Steigerung der Verkaufszahlen von Popcorn und Erfrischungsgetränken in einem Kino eingesetzt. Dies verursachte einen Aufschrei des Entsetzens in der amerikanischen Bevölkerung. Unbewusste Beeinflussung des freien Willens - diese Vorstellung verbreitete große Unsicherheit. Obwohl sich bald alles als ein Schwindel herausstellte, wurde seitdem die unterschwellige Beeinflussung intensiv erforscht. Viele verschiedene Bereiche versuchten die Effektivität zu verifizieren und einen Nutzen daraus zu ziehen. Auch der Einsatz am Computerbildschirm wurde untersucht, mit sehr unterschiedlichen Resultaten. Da sich bei der Steuerung des Blickverhaltens Erfolge zeigten, versucht diese Arbeit, den Blick des Benutzers in Programmoberflächen gezielt auf einzelne Elemente zu lenken. Bisher werden neu erscheinende oder sich bewegende Objekte verwendet, um die Aufmerksamkeit des Benutzers zu erlangen. Da die Augen diesen Reizen nicht widerstehen können, verursachen diese Fokuswechsel beim Benutzer Unterbrechungen und Frustration. Die Oberflächenelemente mit unterschwelligen Hervorhebungen erregen die Aufmerksamkeit des Benutzers im peripheren Gesichtsfeld auf eine subtile Art und Weise, wodurch erzwungene Fokuswechsel und die damit verbundenen Konsequenzen entfallen. Das Ziel ist es dem Benutzer das Gefühl routinierter Arbeit zu vermitteln. In dieser Arbeit wird ein Framework realisiert, das grafische Oberflächenelemente um unterschwellige Einflussmöglichkeiten erweitert. Mithilfe eines Eyetrackers wird die Position des Augenfokus ständig mit der Position des aktuell hervorgehobenen Oberflächenelements verglichen. Kommen sich diese zu nahe, wird der Effekt deaktiviert. Ist der Abstand wieder groß genug, wird der Effekt wieder aktiviert. Dieser Ansatz wird in einer Studie anhand einer Suchaufgabe bestehend aus mehreren Durchgängen mit zweierlei Hervorhebungsvarianten überprüft. Ein Vergleich der Suchzeiten bei Durchgängen mit und ohne dieser Hilfestellung zeigt an, dass die verwendeten unterschwelligen Hervorhebungen die Probanden bei der Suchaufgabe unterstützten. Da der Effekt aber nicht signifikant war, legen die Ergebnisse nahe andere Effekte auf Signifikanz zu überprüfen.In the 1950s a press release about the usage of subliminal advertisements to rise sale of popcorn and soft drinks at the cinema frightened the American population. Unconscious influence on the freedom of will and mind - this idea spread a lot of insecurity. Although it was exposed as a hoax soon, a lot of scientific work from different areas, was invested to verify the effect of subliminal influences and its benefits. Also, usage on the computer screen has been investigated, showing very different results. Subliminal control of the users gaze showed up being effective, this work investigates the opportunity of directing users gaze to individual elements in graphical user interfaces. So far new or moving objects have been used to gain the users' attention. Because eyes just cannot resist these visual influences users work flow is interrupted and frustration is caused. The extended graphical elements of this work will avoid interruptions like that by gaining the users' attention in peripheral field of view in a subtle way. In this thesis a framework is described to extend elements of graphical user interfaces by opportunities of subliminal influence. An eye tracker is used to compare positions of eye focus and highlighted element in realtime. If the distance between eye focus and highlighted element gets too small, the effect is switched off. After gaze moved on to a new position and distance is big enough again, effect is switched on again. A study is conducted to examine this approach by performing a search task for several times using two different kinds of highlighting methods. Comparing search performances with and without subliminal support indicates some user support but no significant effect by the used highlighting methods. Results suggest to test different kinds of highlights for significance

Objective assessment of Visual acuity in infants

Purpose Early detection of abnormal visual acuity (VA) is crucial in the identification and management of ocular and visual abnormalities in infants. Currently, the Teller Acuity Cards (TACs) are considered the gold standard for clinical testing and are effective in obtaining a quick estimate of an infant’s VA, but they have certain drawbacks. They rely on a subjective assessment of the baby’s looking behavior. Despite this, TACs have been found to have good validity and repeatability. The current study investigates a new method to objectively assess visual acuity in infants, which is uses a video gaze tracker (GT) and computer-generated stimuli, developed in the lab of M. Eizenman at the University of Toronto. The purpose was to validate this method in adults and infants against current clinical VA tests. Visual scanning patterns were measured by the GT system that requires minimal subject cooperation in adult and infant populations. The targets were judged as seen when the relative fixation time on the grating exceeded a pre-determined threshold, as compared to the fixation time on the luminance-matched background. Methods Experiment 1: In 15 uncorrected myopic adults, binocular grating VA was measured. The targets were square-wave gratings of spatial frequency ranging from 2.3 to 37 cpd presented randomly in one of four positions on the screen. There were 6 objective protocols (in which VA was judged by fixations). The subjects were naïve, as the only instruction given to the participants was to look towards the screen. The experimenter, who presented the gratings also acted as an observer by making judgments of seen/not seen responses using the objective information provided by the software. Objective GT VA was compared with VA measured with subjective responses using the same stimuli and with Teller Acuity Cards (TACs). Experiment 2: Binocular grating VA for horizontal gratings was measured in 20 typically-developing infants aged 3 to 12 months. Spatial frequency ranged from 0.32 to 42 cpd and VA was measured on two visits with both the GT and TACs. A staircase protocol was used to obtain the VA threshold in the GT. The experimenter controlled the staircase method and an observer used the objective information of visual fixations using the software to judge if the grating was seen or not. Video cartoons were shown between stimulus presentations to keep the infant’s attention towards the screen. VA was also measured with the TACs held in the vertical orientation, so that the gratings were horizontal, similar to the GT method. A TAC stage was specially designed with a vertical slot in which the cards could be presented. The observer was masked regarding the participant’s age and the starting spatial frequency. The study co-ordinator determined the choice of the start card which was randomized between participants so as to give an equal number of participants with each start card. The same start card was used for the second session of each infant. The threshold was defined as the highest spatial frequency for which the infant gave a clear, correct look and an unclear/inconsistent look for the next higher level. The observer, who was masked regarding the absolute spatial frequency, increased or decreased the spatial frequency until this threshold was determined. Results Experiment 1: The mean age of participants in the adult study was 28.47±7.93 yrs and their mean uncorrected logMAR acuity was 0.9±0.2. There was no obvious difference among the mean acuities obtained by 6 objective GT protocols, the subjective GT protocol and the TACs. The GT showed agreement of 93% and 100 % within half an octave compared with the subjective protocol and TACs (horizontal gratings) respectively. There was 100% agreement within 1 octave of the objective GT with both the subjective protocol and the TACs (horizontal gratings). The objective gaze tracker VA showed significant correlation with uncorrected refractive error (r =0.87, p < 0.001). Experiment 2: The mean age of participants was 7.9±2.5 months. In both visits, the testability of the TACs was 100% across all infants. GT had 100% testability on the first visit and 95% testability on the second visit. The mean TAC acuity over two visits for all the infants was 0.7±0.23 log cycles per degree, while the mean log GT acuity over two visits was 0.86±0.30. Infant GT VA acuity estimates were within 1 octave of the TACs 90% and 79% of the time for the first and second visit respectively, while GT VA estimates were within half octave of the TACs 63.2% and 47% of the time for the first and second visit respectively. Eighty-seven percent of the GT VAs and 72.5% of TACs were within one octave of the mean age norms, although on average the GT gave better acuities than the TACs. There was an increase in GT VA with increasing age (r=0.80, p<0.005 for the first visit and r=0.77, p<0.005 for the second visit). Both the TACs and the GT had repeatability of 89.5% within 1 octave between visits and 84.2% and 79% within half octave between visits respectively. Conclusions In adults, the gaze tracker gave VA thresholds which were equivalent to the TACs and were not significantly different from subjectively determined grating VA. The agreement of the GT with TACs in infants and with norms in the infant literature established good validity for the GT. Finally, the significant correlation with age confirmed the validity of the measurements of the gaze tracker. The repeatability of the gaze tracker was similar to that of the TACs, demonstrating the quality usefulness of the test. These results demonstrate the potential for an automated test of infant visual acuity, which could be a powerful and useful tool for visual acuity assessment in infants and other population groups who cannot respond verbally. The staircase protocol established in the study could be fully automated in an objective version of the test. The raw data of eye movements obtained in this study such as the pattern of first fixations, time taken for first fixations, time spent fixing the stimulus, typical stimulus duration and time between presentations could be used to develop algorithms for fully automated testing of VA in infants