8 research outputs found
Improving the performance of GIS/spatial analysts though novel applications of the Emotiv EPOC EEG headset
Geospatial information systems are used to analyze spatial data to provide decision makers with relevant, up-to-date, information. The processing time required for this information is a critical component to response time. Despite advances in algorithms and processing power, we still have many âhuman-in-the-loopâ factors. Given the limited number of geospatial professionals, analysts using their time effectively is very important. The automation and faster humancomputer interactions of common tasks that will not disrupt their workflow or attention is something that is very desirable. The following research describes a novel approach to increase productivity with a wireless, wearable, electroencephalograph (EEG) headset within the geospatial workflow
Online mouse tracking as a measure of attention in videos, using a mouse-contingent bi-resolution display
Master of ScienceDepartment of Psychological SciencesLester C LoschkyData on human visual attention is increasingly collected online, but there are limited tools available to study attention to video stimuli in online experiments. Webcam-based eye tracking is improving, but it faces issues with precision and attrition that prevent its adoption by many researchers. Here I detail an alternative mouse-based paradigm that can be used to measure attention to videos online. This method uses a blurred display and a high-resolution window centered on the userâs computer mouse location. As the user moves their mouse to view different screen content, their mouse movements are recorded, providing an approximation of eye movements and the attended screen location. To validate this Mouse-Contingent Bi-Resolution Display (MCBRD) paradigm, mouse movements collected from online participants watching twenty-seven videos were compared to eye movements from the DIEM dataset. Display settings of window size and blur level were manipulated to identify the settings that resulted in mouse movements most similar to eye movements. This validation study found differences in speed between mouse and eye movements, but similarities in attended regions of interest, especially when the MCBRD screen was blurred with the highest tested Gaussian blur sigma of 0.45 degrees of visual angle. These results suggest that the MCBRD paradigm can be used to measure what regions viewers find salient, interesting, or visually informative in online videos
Assistance visuelle des malvoyants par traitement dâimages adaptatif
This thesis was done in the context of visual impaired needs analysis with the goal of new augmented reality visual assistance device development. The main goal of this work was the development of assistive device for mobility of visual impaired people by the use real-time image processing algorithm which take into account user needs and the context. The first postulate is the use of residual visual acuity of visual impaired people to allow them to see more information. The second postulate is the use only most useful information for visual impaired people for the understanding of the situation where are they. The first research axis was an analysis of needs of visual impaired to identify visual cues, which one we need to enhance to help them. To do this, I have done an immersive stage into a re-adaptation clinic for visually impaired. I have also done a questionnaire to identify and understand how current products answers partially to their needs. The second research axis was the development of a new image processing to answer identified needs. I have developed an interactive tools that allow the user to select the amount of edges for each situation, context. This detector optimizes its result to provide better results than others state of the art evaluated methods. This tool was evaluated and validated during visual test by visual impaired people. We have demonstrated that edges are one of the most important visual cues for visual impaired people to analyze a scene. The third research axis was the development of the augmented reality system to use my tool in a context of mobility. To do this, I have analyzed the needs of visual impaired people for this type of devices. I have also defined main requirements of the desired device for the processing unit, the camera and the display module. For display module, I have analyzed physiologic needs of visually impaired, in terms of profile, colors, and thickness to answer their needs. I have also developed an image generation model which takes into account many physiologic parameters of each observer to create visually comfortable imagesCette thĂšse sâinscrit dans le cadre de lâanalyse des besoins de personnes malvoyantes dans le but de dĂ©velopper de nouvelles solutions dâassistance visuelle en utilisant le principe de rĂ©alitĂ© augmentĂ©e. Le principal objectif de ces travaux Ă©tait le dĂ©veloppement dâun dispositif dâassistance visuelle pour faciliter la mobilitĂ© de personnes malvoyantes grĂące Ă un algorithme qui en temps rĂ©el adapte sa rĂ©ponse en fonction des besoins de lâutilisateur et de la situation dans laquelle il Ă©volue. Le premier postulat de cette thĂšse est dâutiliser lâacuitĂ© rĂ©siduelle fonctionnelle des malvoyants afin de leur permettre de percevoir un certain nombre dâinformations. Le second postulat est dâutiliser les seules informations pertinentes, utiles Ă un malvoyant, afin dâamĂ©liorer sa perception du monde dans lequel il Ă©volue. Le premier axe de recherche a consistĂ© Ă analyser les besoins des malvoyants afin de recenser, les indices visuels utiles Ă rehausser afin dâamĂ©liorer la perception des malvoyants. Cette Ă©tude a Ă©tĂ© rĂ©alisĂ©e en immersion et une enquĂȘte prĂ©cise a Ă©tĂ© menĂ©e auprĂšs de malvoyants. Cette Ă©tude permet de mieux comprendre les besoins des malvoyants, les mĂ©thodes quâils utilisent ainsi que leurs usages des dispositifs actuels. Le deuxiĂšme axe de recherche a consistĂ© Ă concevoir et Ă mettre en oeuvre un algorithme de traitement dâimages rĂ©pondant aux besoins identifiĂ©s. Un outil interactif a Ă©tĂ© dĂ©veloppĂ© qui permet de sĂ©lectionner la quantitĂ© de contours en fonction de la situation. Ce dĂ©tecteur de contour optimise sa dĂ©tection afin dâobtenir des contours plus exploitables pour les malvoyants, comparĂ©s aux rĂ©sultats des autres mĂ©thodes de lâĂ©tat de lâart. Cet outil a Ă©tĂ© testĂ© et validĂ© auprĂšs dâune population donnĂ©e de personnes malvoyantes. Ces tests rĂ©alisĂ©s sur Ă©cran ont dĂ©montrĂ© que les contours constituent des indices visuels trĂšs importants qui peuvent ĂȘtre dâune grande aide dans lâanalyse dâune scĂšne. Le troisiĂšme axe de travail a consistĂ© au dĂ©veloppement dâun systĂšme de rĂ©alitĂ© augmentĂ©e permettant dâutiliser ce dĂ©tecteur de contours dans un contexte de mobilitĂ©. Lâanalyse des besoins des malvoyants vis-Ă -vis dâun tel dispositif nous a permis de dĂ©finir les caractĂ©ristiques indispensables pour le systĂšme de calcul, la camĂ©ra et le dispositif dâaffichage. Concernant le systĂšme dâaffichage, lâanalyse des besoins des malvoyants en termes de profil, de couleur, de largeur des contours, nous a permis de dĂ©finir les paramĂštres nĂ©cessaires pour un affichage qui rĂ©pond Ă ces besoins. Il a Ă©galement Ă©tĂ© pris en compte dans les dĂ©veloppements les paramĂštres physiologiques de chaque observateur afin que les images affichĂ©es soient visuellement confortable
Role of foveal vision in static and dynamic environments
The visual field has multiple regions, with visual acuity being highest in the centre
before declining rapidly outward toward the periphery. This central region,
otherwise known as the fovea, is typically defined as the central 2.0o of vision.
Although comparatively small with respect to other visual field regions, being able
to discern objects of interest in fine detail is only possible in this region. Due to
this, people make ballistic eye movements (saccades) towards the fine details and
depending on the task, may stabilise their gaze in the form of a fixation to
discriminate parts of this newly attended area. A typical everyday task that can
exhibit such behaviours is visual search (scanning a visual environment for objects
or features among distractors), and much of this thesis is concerned with the
importance of foveal vision with respect to visual search tasks. Seven experiments
are presented in this thesis, with chapters 1 â 4 containing a review of the literature,
methodologies and a glossary. In Chapter 5, search experiments with targets of
varying sizes were conducted to assess the role of foveal vision on search
performance. This chapter builds on a debate on whether foveal vision was
necessary for the successful completion of a visual search task. In addition, a novel
algorithm was developed to embed targets at a specified change in local contrast
to automate target placement. The presented results show that the time taken to
find targets with and without foveal vision is nearly identical even when target size
is small. Chapter 6 modulates search difficulty by manipulating salience to
investigate the effect of target size and salience on search performance. Coined the
Compensation Effect, the results of Chapter 6 show that the above-mentioned
variables were able to compensate for one another, resulting in an improved search
performance. This effect occurred regardless of visual field degradation. In the same
chapter, another experiment revealed the stage in the search process where
performance costs originated from, which was the final stage of search concerned
with target verification. Finally, Chapter 7 transitions from static images to
dynamic scenes which simulate self-motion. Additional algorithms were developed,
including an extension to the existing gaze-based decomposition of search time
(Malcolm & Henderson 2009). Chapter 7 investigated the role of foveal vision in
visual search whilst optical flow was present. Unlike previous results, the final
experiments of this thesis revealed the necessity of foveal vision for the attainment
of a normal search performance.
The results of this thesis demonstrate that the importance of foveal vision with
respect to visual search is modulated by the stimulus environment, with it being
relatively unimportant for static scenes, but important for dynamic scenes
Evaluation of visualisations of geographically weighted regression, with perceptual stability
Given the large volume of data that is regularly accumulated, the need to properly manage,
efficiently display and correctly interpret, becomes more important. Complex analysis of data
is best performed using statistical models and in particular those with a geographical element
are best analysed using Spatial Statistical Methods, including local regression. Spatial Statistical
Methods are employed in a wide range of disciplines to analyse and interpret data where it is
necessary to detect significant spatial patterns or relationships. The topic of the research
presented in this thesis is an exploration of the most effective methods of visualising results.
A human being is capable of processing a vast amount of data as long as it is effectively
displayed. However, the perceptual load will at some point exceed the cognitive processing
ability and therefore the ability to comprehend data. Although increases in data scale did
increase the cognitive load and reduce processing, prior knowledge of geographical information
systems did not result in an overall processing advantage.
The empirical work in the thesis is divided into two parts. The first part aims to gain insight into
visualisations which would be effective for interpretation and analysis of Geographically
Weighted Regression (GWR), a popular Spatial Statistical Method. Three different visualisation
techniques; two dimensional, three dimensional and interactive, are evaluated through an
experiment comprising two data set sizes. Interactive visualisations perform best overall,
despite the apparent lack of researcher familiarity.
The increase in data volume can present additional complexity for researchers. Although the
evaluation of the first experiment augments understanding of effective visualisation display,
the scale at which data can be adequately presented within these visualisations is unclear.
Therefore, the second empirical investigation seeks to provide insight into data scalability, and
human cognitive limitations associated with data comprehension.
The general discussion concludes that there is a need to better inform researchers of the
potential of interactive visualisations. People do need to be properly trained to use these
systems, but the limits of human perceptual processing also need to be considered in order to
permit more efficient and insightful analysis
BlickpunktabhÀngige Computergraphik
Contemporary digital displays feature multi-million pixels at ever-increasing refresh rates. Reality, on the other hand, provides us with a view of the world that is continuous in space and time. The discrepancy between viewing the physical world and its sampled depiction on digital displays gives rise to perceptual quality degradations. By measuring or estimating where we look, gaze-contingent algorithms aim at exploiting the way we visually perceive to remedy visible artifacts. This dissertation presents a variety of novel gaze-contingent algorithms and respective perceptual studies. Chapter 4 and 5 present methods to boost perceived visual quality of conventional video footage when viewed on commodity monitors or projectors. In Chapter 6 a novel head-mounted display with real-time gaze tracking is described. The device enables a large variety of applications in the context of Virtual Reality and Augmented Reality. Using the gaze-tracking VR headset, a novel gaze-contingent render method is described in Chapter 7. The gaze-aware approach greatly reduces computational efforts for shading virtual worlds. The described methods and studies show that gaze-contingent algorithms are able to improve the quality of displayed images and videos or reduce the computational effort for image generation, while display quality perceived by the user does not change.Moderne digitale Bildschirme ermöglichen immer höhere Auflösungen bei ebenfalls steigenden Bildwiederholraten. Die RealitĂ€t hingegen ist in Raum und Zeit kontinuierlich. Diese Grundverschiedenheit fĂŒhrt beim Betrachter zu perzeptuellen Unterschieden. Die Verfolgung der Aug-Blickrichtung ermöglicht blickpunktabhĂ€ngige Darstellungsmethoden, die sichtbare Artefakte verhindern können. Diese Dissertation trĂ€gt zu vier Bereichen blickpunktabhĂ€ngiger und wahrnehmungstreuer Darstellungsmethoden bei. Die Verfahren in Kapitel 4 und 5 haben zum Ziel, die wahrgenommene visuelle QualitĂ€t von Videos fĂŒr den Betrachter zu erhöhen, wobei die Videos auf gewöhnlicher Ausgabehardware wie z.B. einem Fernseher oder Projektor dargestellt werden. Kapitel 6 beschreibt die Entwicklung eines neuartigen Head-mounted Displays mit UnterstĂŒtzung zur Erfassung der Blickrichtung in Echtzeit. Die Kombination der Funktionen ermöglicht eine Reihe interessanter Anwendungen in Bezug auf Virtuelle RealitĂ€t (VR) und Erweiterte RealitĂ€t (AR). Das vierte und abschlieĂende Verfahren in Kapitel 7 dieser Dissertation beschreibt einen neuen Algorithmus, der das entwickelte Eye-Tracking Head-mounted Display zum blickpunktabhĂ€ngigen Rendern nutzt. Die QualitĂ€t des Shadings wird hierbei auf Basis eines Wahrnehmungsmodells fĂŒr jeden Bildpixel in Echtzeit analysiert und angepasst. Das Verfahren hat das Potenzial den Berechnungsaufwand fĂŒr das Shading einer virtuellen Szene auf ein Bruchteil zu reduzieren. Die in dieser Dissertation beschriebenen Verfahren und Untersuchungen zeigen, dass blickpunktabhĂ€ngige Algorithmen die DarstellungsqualitĂ€t von Bildern und Videos wirksam verbessern können, beziehungsweise sich bei gleichbleibender BildqualitĂ€t der Berechnungsaufwand des bildgebenden Verfahrens erheblich verringern lĂ€sst