Enhanced Virtuality: Increasing the Usability and Productivity of Virtual Environments

Mit stetig steigender Bildschirmauflösung, genauerem Tracking und fallenden Preisen stehen Virtual Reality (VR) Systeme kurz davor sich erfolgreich am Markt zu etablieren. Verschiedene Werkzeuge helfen Entwicklern bei der Erstellung komplexer Interaktionen mit mehreren Benutzern innerhalb adaptiver virtueller Umgebungen. Allerdings entstehen mit der Verbreitung der VR-Systeme auch zusätzliche Herausforderungen: Diverse Eingabegeräte mit ungewohnten Formen und Tastenlayouts verhindern eine intuitive Interaktion. Darüber hinaus zwingt der eingeschränkte Funktionsumfang bestehender Software die Nutzer dazu, auf herkömmliche PC- oder Touch-basierte Systeme zurückzugreifen. Außerdem birgt die Zusammenarbeit mit anderen Anwendern am gleichen Standort Herausforderungen hinsichtlich der Kalibrierung unterschiedlicher Trackingsysteme und der Kollisionsvermeidung. Beim entfernten Zusammenarbeiten wird die Interaktion durch Latenzzeiten und Verbindungsverluste zusätzlich beeinflusst. Schließlich haben die Benutzer unterschiedliche Anforderungen an die Visualisierung von Inhalten, z.B. Größe, Ausrichtung, Farbe oder Kontrast, innerhalb der virtuellen Welten. Eine strikte Nachbildung von realen Umgebungen in VR verschenkt Potential und wird es nicht ermöglichen, die individuellen Bedürfnisse der Benutzer zu berücksichtigen. Um diese Probleme anzugehen, werden in der vorliegenden Arbeit Lösungen in den Bereichen Eingabe, Zusammenarbeit und Erweiterung von virtuellen Welten und Benutzern vorgestellt, die darauf abzielen, die Benutzerfreundlichkeit und Produktivität von VR zu erhöhen. Zunächst werden PC-basierte Hardware und Software in die virtuelle Welt übertragen, um die Vertrautheit und den Funktionsumfang bestehender Anwendungen in VR zu erhalten. Virtuelle Stellvertreter von physischen Geräten, z.B. Tastatur und Tablet, und ein VR-Modus für Anwendungen ermöglichen es dem Benutzer reale Fähigkeiten in die virtuelle Welt zu übertragen. Des Weiteren wird ein Algorithmus vorgestellt, der die Kalibrierung mehrerer ko-lokaler VR-Geräte mit hoher Genauigkeit und geringen Hardwareanforderungen und geringem Aufwand ermöglicht. Da VR-Headsets die reale Umgebung der Benutzer ausblenden, wird die Relevanz einer Ganzkörper-Avatar-Visualisierung für die Kollisionsvermeidung und das entfernte Zusammenarbeiten nachgewiesen. Darüber hinaus werden personalisierte räumliche oder zeitliche Modifikationen vorgestellt, die es erlauben, die Benutzerfreundlichkeit, Arbeitsleistung und soziale Präsenz von Benutzern zu erhöhen. Diskrepanzen zwischen den virtuellen Welten, die durch persönliche Anpassungen entstehen, werden durch Methoden der Avatar-Umlenkung (engl. redirection) kompensiert. Abschließend werden einige der Methoden und Erkenntnisse in eine beispielhafte Anwendung integriert, um deren praktische Anwendbarkeit zu verdeutlichen. Die vorliegende Arbeit zeigt, dass virtuelle Umgebungen auf realen Fähigkeiten und Erfahrungen aufbauen können, um eine vertraute und einfache Interaktion und Zusammenarbeit von Benutzern zu gewährleisten. Darüber hinaus ermöglichen individuelle Erweiterungen des virtuellen Inhalts und der Avatare Einschränkungen der realen Welt zu überwinden und das Erlebnis von VR-Umgebungen zu steigern

Real-time people tracking in a camera network

Visual tracking is a fundamental key to the recognition and analysis of human behaviour. In this thesis we present an approach to track several subjects using multiple cameras in real time. The tracking framework employs a numerical Bayesian estimator, also known as a particle lter, which has been developed for parallel implementation on a Graphics Processing Unit (GPU). In order to integrate multiple cameras into a single tracking unit we represent the human body by a parametric ellipsoid in a 3D world. The elliptical boundary can be projected rapidly, several hundred times per subject per frame, onto any image for comparison with the image data within a likelihood model. Adding variables to encode visibility and persistence into the state vector, we tackle the problems of distraction and short-period occlusion. However, subjects may also disappear for longer periods due to blind spots between cameras elds of view. To recognise a desired subject after such a long-period, we add coloured texture to the ellipsoid surface, which is learnt and retained during the tracking process. This texture signature improves the recall rate from 60% to 70-80% when compared to state only data association. Compared to a standard Central Processing Unit (CPU) implementation, there is a signi cant speed-up ratio

The Preferred Retinal Locus in Macular Degeneration: Relating Structure and Function

Purpose: Central field loss (CFL) that ensues from macular degeneration can impact many activities of daily living, including reading, in both younger (as in Stargardt disease, STGD) and older (age-related macular degeneration, AMD) subjects. Subjects with CFL typically choose a non-central retinal location, called the preferred retinal locus (PRL) for fixation. This dissertation aims to understand and relate functional and structural changes within the PRL. Methods: Preliminary studies determined the effectiveness of the MP-1 microperimeter (a) to compensate for excessively unstable fixational eye movements (FEMs), such as occur in subjects with CFL, and (b) to accurately register the retinal test locations on baseline and subsequent automated follow-up testing. Subsequently, the following functional measures were obtained for 29 subjects with bilateral CFL: (a) reading performance using hand-held MNRead charts and LCD-displayed MP1 Read charts, (b) contrast-detection thresholds using the Freiburg acuity test, (c) fixation stability on 3-letter words, measured as bivariate contour ellipse areas (BCEAs) with the MP-1, (d) sensitivity in the central visual field determined with a standard 10-2 threshold grid, and (e) fine-grained sensitivity within the word-fixation PRL for supra-threshold 13x13 arc min spots. Spectral-domain optical coherence tomography (SD-OCT) was used to assess structural characteristics of the PRL, specifically, thickness ratios for the retinal pigment epithelium - Bruch’s membrane complex (RPE-BM), the photoreceptor and outer nuclear layer (PL), and the total retina layers (TRL) between PRL locations where test spots were and were not consistently detected. Finally, 8 younger (50 years) naive subjects with normal vision read high and low contrast sentences presented one word at a time at the fovea and 5 and 10° in the inferior field. Random 13x13 arc min blocks corresponding to 0-78% of the text area were set to the background luminance to simulate retinal micro-scotomas (MSs) and a staircase algorithm estimated the threshold reading rate. Results: The MP-1 compensated ~90% of the experimentally induced increase in FEMs and the average registration error was ~8 arc min. The maximum reading speed of subjects with CFL correlated poorly with contrast thresholds, BCEA, PRL eccentricity, median sensitivity around the PRL and all retinal thickness ratios. Twenty-two of 29 subjects with CFL (AMD: 8/10 subjects; STGD: 10/12 subjects) exhibited one or more MSs, defined as local regions of insensitivity for supra-threshold targets within the PRL. Although the average percentage of MSs was similar in the cohorts with AMD (25.4%) and STGD (20.3%), reading speed was significantly faster in STGD than AMD subjects. Average thickness ratios for RPE-BM, PL and TRL were 0.97, 0.84 and 0.86 respectively in the AMD cohort and 0.97, 0.77 and 0.89 respectively in the STGD cohort. Only TRL in subjects with AMD differed significantly from 1. In normally-sighted subjects, log reading rate decreased significantly with decreasing contrast and increasing age, eccentricity, and density of element-deletions. For a given eccentricity and contrast, a higher density of element-deletions maximally affected the older subjects. Conclusion: The compensation of the MP-1 for excessive FEMs and the registration between retinal test locations during baseline and follow-up testing are sufficient to assess functional changes within local retinal regions in subjects with CFL. MSs exist within the PRL of a high proportion of subjects with CFL, but are not strongly associated with structural changes determined using SD-OCT. Based on a simulation in normally-sighted subjects, we expect impact of MSs on reading to be greater for older than younger subjects with CFL.Optometry, College o

Adventures in software engineering : plugging HCI & acessibility gaps with open source solutions

There has been a great deal of research undertaken in the field of Human-Computer Interfaces (HCI), input devices, and output modalities in recent years. From touch-based and voice control input mechanisms such as those found on modern smart-devices to the use of touch-free input through video-stream/image analysis (including depth streams and skeletal mapping) and the inclusion of gaze tracking, head tracking, virtual reality and beyond - the availability and variety of these I/O (Input/Output) mechanisms has increased tremendously and progressed both into our living rooms and into our lives in general. With regard to modern desktop computers and videogame consoles, at present many of these technologies are at a relatively immature stage of development - their use often limited to simple adjuncts to the staple input mechanisms of mouse, keyboard, or joystick / joypad inputs. In effect, we have these new input devices - but we're not quite sure how best to use them yet; that is, where their various strengths and weaknesses lie, and how or if they can be used to conveniently and reliably drive or augment applications in our everyday lives. In addition, much of this technology is provided by proprietary hardware and software, providing limited options for customisation or adaptation to better meet the needs of specific users. Therefore, this project investigated the development of open source software solutions to address various aspects of innovative user I/O in a flexible manner. Towards this end, a number of original software applications have been developed which incorporate functionality aimed at enhancing the current state of the art in these areas and making that software freely available for use by any who may find it beneficial.Doctor of Philosoph

Character Recognition

Character recognition is one of the pattern recognition technologies that are most widely used in practical applications. This book presents recent advances that are relevant to character recognition, from technical topics such as image processing, feature extraction or classification, to new applications including human-computer interfaces. The goal of this book is to provide a reference source for academic research and for professionals working in the character recognition field

The 25th Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting

Papers in the following categories are presented: recent developments in rubidium, cesium, and hydrogen-based frequency standards, and in cryogenic and trapped-ion technology; international and transnational applications of precise time and time interval (PTTI) technology with emphasis on satellite laser tracking networks, GLONASS timing, intercomparison of national time scales and international telecommunication; applications of PTTI technology to the telecommunications, power distribution, platform positioning, and geophysical survey industries; application of PTTI technology to evolving military communications and navigation systems; and dissemination of precise time and frequency by means of GPS, GLONASS, MILSTAR, LORAN, and synchronous communications satellites

The factors impacting Critical Care Nurses' decision-making processes in continuous renal replacement therapy.

IntroductionContinuous Renal Replacement Therapy (CRRT) is a common treatment intervention in critical care units worldwide. It provides supportive therapy for critically ill patients with severe kidney dysfunction. Efforts to optimise its clinical effectiveness through modifying treatment regimens over recent years have proved largely unsuccessful. However, studies have not explored the human element of critical care nurses delivering CRRT.AimThis study is designed to understand the influences on critical care nurses’ decision-making in the management of CRRT. In doing so, develop and highlight areas where modifications in practices can be adopted, in order to improve both the patient and organisational quality indicators associated with CRRT delivery.MethodsThis study used an adaptive Interpretive Description approach. The study was conducted across four linked United Kingdom critical care units. Twenty- one (n=21) registered critical care nurses undertook the California Critical Thinking Disposition Inventory (CCTDI) and of these, 10 nurses were interviewed face to face in semi-structured audio recorded interview, which were then transcribed and thematically analysed.ResultsFour major themes influencing critical care nurses decision-making regarding CRRT were identified, with a further two contributing an overarching influence. These themes were the Individual; Organisational; Practice; Support, these themes were complex and intertwined and in themselves highlighted issues about Variability and Competing demands whilst delivering CRRT.DiscussionThe themes in this study showed an alignment with some of the findings from other critical care decision-making studies, including the influence of the individual nurse, experience, and support. However, this work has also been able to introduce significant new knowledge on the perceptions and insights of critical care nurses. These findings generate new knowledge and contextualise these understandings of individuals, the organisations, the wider interactions, and relationships between colleagues, and the CRRT technology, and provide insights to enable a holistic approach to understanding the provision of CRRT and potentially enable improvements in treatment delivery. In understanding these aspects, it has elucidated avenues for improvements in practice, identifying areas that can be engineered to improve CRRT practice and characterises elements within individuals which contribute to CRRT delivery.RecommendationsThis study draws up a number of recommendations from the themes identified, these recommendations focus on the ‘Individual’ and the ‘Organisational’ themes. They include the introduction of a harmonised training, educational and competency programmes with integrated in situ hi-fidelity simulation provision, alongside bespoke high quality clinical supervision, to facilitate critical care nurses self-awareness