Natural freehand grasping of virtual objects for augmented reality

Grasping is a primary form of interaction with the surrounding world, and is an intuitive interaction technique by nature due to the highly complex structure of the human hand. Translating this versatile interaction technique to Augmented Reality (AR) can provide interaction designers with more opportunities to implement more intuitive and realistic AR applications. The work presented in this thesis uses quantifiable measures to evaluate the accuracy and usability of natural grasping of virtual objects in AR environments, and presents methods for improving this natural form of interaction. Following a review of physical grasping parameters and current methods of mediating grasping interactions in AR, a comprehensive analysis of natural freehand grasping of virtual objects in AR is presented to assess the accuracy, usability and transferability of this natural form of grasping to AR environments. The analysis is presented in four independent user studies (120 participants, 30 participants for each study and 5760 grasping tasks in total), where natural freehand grasping performance is assessed for a range of virtual object sizes, positions and types in terms of accuracy of grasping, task completion time and overall system usability. Findings from the first user study in this work highlighted two key problems for natural grasping in AR; namely inaccurate depth estimation and inaccurate size estimation of virtual objects. Following the quantification of these errors, three different methods for mitigating user errors and assisting users during natural grasping were presented and analysed; namely dual view visual feedback, drop shadows and additional visual feedback when adding user based tolerances during interaction tasks. Dual view visual feedback was found to significantly improve user depth estimation, however this method also significantly increased task completion time. Drop shadows provided an alternative, and a more usable solution, to dual view visual feedback through significantly improving depth estimation, task completion time and the overall usability of natural grasping. User based tolerances negated the fundamental problem of inaccurate size estimation of virtual objects, through enabling users to perform natural grasping without the need of being highly accurate in their grasping performance, thus providing evidence that natural grasping can be usable in task based AR environments. Finally recommendations for allowing and further improving natural grasping interaction in AR environments are provided, along with guidelines for translating this form of natural grasping to other AR environments and user interfaces

Freeform User Interfaces for Graphical Computing

報告番号: 甲15222 ; 学位授与年月日: 2000-03-29 ; 学位の種別: 課程博士 ; 学位の種類: 博士(工学) ; 学位記番号: 博工第4717号 ; 研究科・専攻: 工学系研究科情報工学専

Image Retrieval within Augmented Reality

Die vorliegende Arbeit untersucht das Potenzial von Augmented Reality zur Verbesserung von Image Retrieval Prozessen. Herausforderungen in Design und Gebrauchstauglichkeit wurden für beide Forschungsbereiche dargelegt und genutzt, um Designziele für Konzepte zu entwerfen. Eine Taxonomie für Image Retrieval in Augmented Reality wurde basierend auf der Forschungsarbeit entworfen und eingesetzt, um verwandte Arbeiten und generelle Ideen für Interaktionsmöglichkeiten zu strukturieren. Basierend auf der Taxonomie wurden Anwendungsszenarien als weitere Anforderungen für Konzepte formuliert. Mit Hilfe der generellen Ideen und Anforderungen wurden zwei umfassende Konzepte für Image Retrieval in Augmented Reality ausgearbeitet. Eins der Konzepte wurde auf einer Microsoft HoloLens umgesetzt und in einer Nutzerstudie evaluiert. Die Studie zeigt, dass das Konzept grundsätzlich positiv aufgenommen wurde und bietet Erkenntnisse über unterschiedliches Verhalten im Raum und verschiedene Suchstrategien bei der Durchführung von Image Retrieval in der erweiterten Realität.:1 Introduction 1.1 Motivation and Problem Statement 1.1.1 Augmented Reality and Head-Mounted Displays 1.1.2 Image Retrieval 1.1.3 Image Retrieval within Augmented Reality 1.2 Thesis Structure 2 Foundations of Image Retrieval and Augmented Reality 2.1 Foundations of Image Retrieval 2.1.1 Definition of Image Retrieval 2.1.2 Classification of Image Retrieval Systems 2.1.3 Design and Usability in Image Retrieval 2.2 Foundations of Augmented Reality 2.2.1 Definition of Augmented Reality 2.2.2 Augmented Reality Design and Usability 2.3 Taxonomy for Image Retrieval within Augmented Reality 2.3.1 Session Parameters 2.3.2 Interaction Process 2.3.3 Summary of the Taxonomy 3 Concepts for Image Retrieval within Augmented Reality 3.1 Related Work 3.1.1 Natural Query Specification 3.1.2 Situated Result Visualization 3.1.3 3D Result Interaction 3.1.4 Summary of Related Work 3.2 Basic Interaction Concepts for Image Retrieval in Augmented Reality 3.2.1 Natural Query Specification 3.2.2 Situated Result Visualization 3.2.3 3D Result Interaction 3.3 Requirements for Comprehensive Concepts 3.3.1 Design Goals 3.3.2 Application Scenarios 3.4 Comprehensive Concepts 3.4.1 Tangible Query Workbench 3.4.2 Situated Photograph Queries 3.4.3 Conformance of Concept Requirements 4 Prototypic Implementation of Situated Photograph Queries 4.1 Implementation Design 4.1.1 Implementation Process 4.1.2 Structure of the Implementation 4.2 Developer and User Manual 4.2.1 Setup of the Prototype 4.2.2 Usage of the Prototype 4.3 Discussion of the Prototype 5 Evaluation of Prototype and Concept by User Study 5.1 Design of the User Study 5.1.1 Usability Testing 5.1.2 Questionnaire 5.2 Results 5.2.1 Logging of User Behavior 5.2.2 Rating through Likert Scales 5.2.3 Free Text Answers and Remarks during the Study 5.2.4 Observations during the Study 5.2.5 Discussion of Results 6 Conclusion 6.1 Summary of the Present Work 6.2 Outlook on Further WorkThe present work investigates the potential of augmented reality for improving the image retrieval process. Design and usability challenges were identified for both fields of research in order to formulate design goals for the development of concepts. A taxonomy for image retrieval within augmented reality was elaborated based on research work and used to structure related work and basic ideas for interaction. Based on the taxonomy, application scenarios were formulated as further requirements for concepts. Using the basic interaction ideas and the requirements, two comprehensive concepts for image retrieval within augmented reality were elaborated. One of the concepts was implemented using a Microsoft HoloLens and evaluated in a user study. The study showed that the concept was rated generally positive by the users and provided insight in different spatial behavior and search strategies when practicing image retrieval in augmented reality.:1 Introduction 1.1 Motivation and Problem Statement 1.1.1 Augmented Reality and Head-Mounted Displays 1.1.2 Image Retrieval 1.1.3 Image Retrieval within Augmented Reality 1.2 Thesis Structure 2 Foundations of Image Retrieval and Augmented Reality 2.1 Foundations of Image Retrieval 2.1.1 Definition of Image Retrieval 2.1.2 Classification of Image Retrieval Systems 2.1.3 Design and Usability in Image Retrieval 2.2 Foundations of Augmented Reality 2.2.1 Definition of Augmented Reality 2.2.2 Augmented Reality Design and Usability 2.3 Taxonomy for Image Retrieval within Augmented Reality 2.3.1 Session Parameters 2.3.2 Interaction Process 2.3.3 Summary of the Taxonomy 3 Concepts for Image Retrieval within Augmented Reality 3.1 Related Work 3.1.1 Natural Query Specification 3.1.2 Situated Result Visualization 3.1.3 3D Result Interaction 3.1.4 Summary of Related Work 3.2 Basic Interaction Concepts for Image Retrieval in Augmented Reality 3.2.1 Natural Query Specification 3.2.2 Situated Result Visualization 3.2.3 3D Result Interaction 3.3 Requirements for Comprehensive Concepts 3.3.1 Design Goals 3.3.2 Application Scenarios 3.4 Comprehensive Concepts 3.4.1 Tangible Query Workbench 3.4.2 Situated Photograph Queries 3.4.3 Conformance of Concept Requirements 4 Prototypic Implementation of Situated Photograph Queries 4.1 Implementation Design 4.1.1 Implementation Process 4.1.2 Structure of the Implementation 4.2 Developer and User Manual 4.2.1 Setup of the Prototype 4.2.2 Usage of the Prototype 4.3 Discussion of the Prototype 5 Evaluation of Prototype and Concept by User Study 5.1 Design of the User Study 5.1.1 Usability Testing 5.1.2 Questionnaire 5.2 Results 5.2.1 Logging of User Behavior 5.2.2 Rating through Likert Scales 5.2.3 Free Text Answers and Remarks during the Study 5.2.4 Observations during the Study 5.2.5 Discussion of Results 6 Conclusion 6.1 Summary of the Present Work 6.2 Outlook on Further Wor

Evaluation of Drop Shadows for Virtual Object Grasping in Augmented Reality

This paper presents the use of rendered visual cues as drop shadows and their impact on overall usability and accuracy of grasping interactions for monitor-based exocentric Augmented Reality (AR). We report on two conditions; grasping with drop shadows and without drop shadows and analyse a total of 1620 grasps of two virtual object types (cubes and spheres). We report on the accuracy of one grasp type, the Medium Wrap grasp, against Grasp Aperture (GAp), Grasp Displacement (GDisp), completion time and usability metrics from 30 participants. A comprehensive statistical analysis of the results is presented giving comparisons of the inclusion of drop shadows in AR grasping. Findings showed that the use of drop shadows increases usability of AR grasping while significantly decreasing task completion times. Furthermore, drop shadows also significantly improve user’s depth estimation of AR object position. However, this study also shows that using drop shadows does not improve user’s object size estimation, which remains as a problematic element in grasping AR interaction literature

Augmentation Of Human Skill In Microsurgery

Surgeons performing highly skilled microsurgery tasks can benefit from information and manual assistance to overcome technological and physiological limitations to make surgery safer, efficient, and more successful. Vitreoretinal surgery is particularly difficult due to inherent micro-scale and fragility of human eye anatomy. Additionally, surgeons are challenged by physiological hand tremor, poor visualization, lack of force sensing, and significant cognitive load while executing high-risk procedures inside the eye, such as epiretinal membrane peeling. This dissertation presents the architecture and the design principles for a surgical augmentation environment which is used to develop innovative functionality to address the fundamental limitations in vitreoretinal surgery. It is an inherently information driven modular system incorporating robotics, sensors, and multimedia components. The integrated nature of the system is leveraged to create intuitive and relevant human-machine interfaces and generate a particular system behavior to provide active physical assistance and present relevant sensory information to the surgeon. These include basic manipulation assistance, audio-visual and haptic feedback, intraoperative imaging and force sensing. The resulting functionality, and the proposed architecture and design methods generalize to other microsurgical procedures. The system's performance is demonstrated and evaluated using phantoms and in vivo experiments

Freehand Digital Drawing: a Boost to Creative Design. The Observer's Eye and the Draftsman Brain

[ES] La representación de un proyecto arquitectónico tiene diferentes finalidades, una de las más relevantes es su visualización. El tema de esta tesis es la relación entre el diseñador, su actividad cerebral durante la fase creativa, el proyecto representado y la mente del observador. La pregunta, planteada por arquitectos, diseñadores y académicos en los años ochenta y aún abierta a soluciones estimulantes, es una pregunta bien conocida sobre si la creciente digitalización puede ser perjudicial o beneficiosa para esta relación. Después de un análisis de la imagen en la arquitectura a partir del Renacimiento, informado en la Parte 1, se revisan y discuten las técnicas actuales de representación. La primera pregunta, abordada en la Parte 2, fue si la simulación de la realidad con renderizado de calidad fotográfica garantiza una visualización mejor o peor que una imagen tradicionalmente dibujada a mano. Se elaboró un cuestionario para verificar las características de comunicación y representación de las imágenes producidas con las dos técnicas. Los resultados mostraron que estas dos cualidades estaban más presentes en el caso del dibujo a mano alzada que en los renders fotorrealistas. La Parte 3 se centró en el diseñador y utilizó las herramientas proporcionadas por la neurociencia, a saber, el EEG y las 'respuestas evocadas', para cuantificar la actividad cerebral de alguien que hace un dibujo a mano alzada con respecto a CAD. Dado que la tecnología utilizada nunca antes se había aplicado a un sujeto al realizar un diseño, la investigación se dividió en tres experimentos separados. El primero se dedicó a encontrar una forma confiable de realizar registros durante el movimiento del miembro superior en la ejecución del dibujo; los experimentos segundo y tercero tenían como objetivo el análisis específico de la actividad cerebral que precede y sigue a los movimientos individuales de los signos trazados. Los resultados mostraron que la actividad motora relacionada con el dibujo a mano alzada estuvo acompañada por un aumento en la amplitud de las respuestas electroencefalográficas en comparación con el dibujo con CAD. Este dato es probablemente un importante paso adelante a favor de la hipótesis de que la creatividad también puede mejorarse mediante el movimiento en el dibujo a mano alzada. La conclusión es que las imágenes así dibujadas crean una mejor correspondencia entre el autor y el observador, y que el movimiento y la percepción sensorial de la mano pueden fomentar la creatividad. Recientemente, los avances en la técnica de las tabletas de dibujo han proporcionado una nueva técnica para el dibujo a mano alzada, donde se combina la capacidad de gestión de datos del ordenador con los gestos naturales tradicionalmente ligados al uso del papel y el lápiz. de la tecnología moderna puede fusionar el factor humano junto con las nuevas tecnologías digitales.[CA] La representació d'un projecte arquitectònic té diferents finalitats, una de les més rellevants és la seva visualització. El tema d'aquesta tesi és la relació entre el dissenyador, la seva activitat cerebral durant la fase creativa, el projecte representat i la ment de l'observador. La pregunta, plantejada per arquitectes, dissenyadors i estudiosos als anys vuitanta i encara oberta a solucions estimulants, és una qüestió ben coneguda si augmentar la digitalització pot ser perjudicial o beneficiós per a aquesta relació. Després d'una anàlisi de la imatge en arquitectura a partir del període renaixentista, informada a la part 1, es revisen i discuteixen les tècniques de representació actuals. La primera pregunta, abordada a la part 2, va ser si la simulació de la realitat amb renderització de qualitat fotogràfica garanteix una visualització millor o pitjor que una imatge tradicionalment dibuixada a mà. Es va elaborar un qüestionari per comprovar les característiques de comunicació i representació de les imatges produïdes amb les dues tècniques. Els resultats van mostrar que aquestes dues qualitats estaven més presents en el cas del dibuix a mà alçada que en els renders fotorealistes. La part 3 es va centrar en el dissenyador i va utilitzar les eines proporcionades per la neurociència, és a dir, l'EEG i les 'respostes evocades', per quantificar l'activitat cerebral d'algú que realitza un dibuix a mà alçada respecte al CAD. Com que la tecnologia utilitzada mai abans s'havia aplicat a un tema mentre es feia un disseny, la investigació es va dividir en tres experiments separats. El primer es va dedicar a trobar una manera fiable de fer enregistraments durant el moviment de l'extremitat superior en l'execució del dibuix; el segon i el tercer experiment estaven dirigits a l'anàlisi específica de l'activitat cerebral que precedeix i segueix els moviments individuals dels signes traçats. Els resultats van mostrar que l'activitat motora relacionada amb el dibuix a mà alçada va anar acompanyada d'un augment de l'amplitud de les respostes electroencefalogràfiques en comparació amb el dibuix amb CAD. Aquesta dada és probablement un pas endavant significatiu a favor de la hipòtesi que la creativitat també es pot millorar amb el moviment en el dibuix a mà alçada. La conclusió és que les imatges dibuixades d'aquesta manera creen una millor correspondència entre autor i observador, i que el moviment i la percepció sensorial de la mà poden fomentar la creativitat. Recentment, els avenços en la tècnica de dibuix a tauletes han aportat una nova tècnica de dibuix a mà alçada, on la capacitat de gestió de dades de l'ordinador es combina amb els gestos naturals tradicionalment vinculats a l'ús del paper i el llapis. de la tecnologia moderna pot fusionar el factor humà amb les noves tecnologies digitals.[EN] The representation of an architectural project aims at several intents, one of the most relevant being the visualisation of a design. The subject of this dissertation is therefore the relationship between the draftsman, the creativity of his brain, the represented design, and the mind of the observer. Since the Eighties, architects, designers and scholars wondered whether the current habit of an ever increasing digitalisation could be detrimental or advantageous to such relationship. After an analysis of architectural imaging since the Renaissance, as reported in Part 1, the current techniques are reviewed and discussed. The first question, addressed in Part 2, has been whether the simulation of reality with renders of photographic quality, would relate to the observer better or worse than a traditionally hand drawn image. A questionnaire has been constructed to probe the communication and representation qualities of the images. The results suggested that these two qualities were best represented in the case of freehand drawing compared to photorealistic renders. Part 3 was focused on the designer and used the instruments provided by neuroscience, i.e. the EEG and 'evoked responses', to quantify the brain activity in connection with freehand and CAD drawing. Because the involved technology had never been applied before to a drawing subject, the investigation had to be divided into three separate experiments. The first one was dedicated to finding a reliable way to perform the recordings in subjects who freely moved their arm and hand while drawing. The second and third experiments were aimed at analysing the cerebral activity occurring before and after each drawing movement. All results demonstrated that a larger cerebral activity preceded and followed each movement in freehand drawing compared to CAD design. This finding may be considered a robust step towards the notion that also creativity may consequently be improved. The final conclusion is that the freehand drawn images make a better link between author and observer, and at the same time the very movement and haptic perception of the hand elicit creativity. Indeed, the most recent advances in technology of drawing tablets have provided a new medium for freehand drawing, which can exploit the capacity of data handling of computers with the natural movement of using pencil and paper, ending up in a traditional hand made product. A wise usage of modern technology can therefore merge the human factor with the digital world.Leandri, G. (2022). Freehand Digital Drawing: a Boost to Creative Design. The Observer's Eye and the Draftsman Brain [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/188091TESI

FREEHAND DIGITAL DRAWING: A BOOST TO CREATIVE DESIGN. THE OBSERVER’S EYE AND THE DRAFTSMAN’S BRAIN

Representation of an architectural project aims at several intents; one of the most relevant being the visualization of a design. The subject of this dissertation is therefore the relationship between the draftsman, the creativity of his brain, the represented design, and the mind of the observer, while raising the question whether the current habit of an ever increasing digitalisation may be detrimental or advantageous to such relationship. After an analysis of architectural representation in history since Renaissance times, as reported in Part 1, the current techniques are reviewed and discussed. The first question, addressed in Part 2, has been whether the simulation of reality with renders of photographic quality, a product of automated computerisation, would relate to the observer better or worse than a traditionally hand drawn image. A questionnaire has been constructed to probe the communication and representation qualities of the images. The results suggested that these two qualities were best represented in the case of freehand drawing compared to photorealistic renders. The Part 3 was focused on the designer and used the instruments provided by neuroscience, i.e. the EEG and evoked responses, to quantify the brain activity in connection with freehand and CAD drawing. Because the involved technology had never been applied before to a drawing subject, the investigation had to be divided into three separate experiments. The first was dedicated to find a reliable way to perform the recordings in a subject who freely moved arm and hand while drawing for a few minutes; the second and third experiment were aimed at the analysis of cerebral activity occurring before and after the drawing movement. All results demonstrated that a definitely larger cerebral activity preceded and followed each movement in freehand drawing compared to CAD design. This finding may be considered a robust step towards the notion that also creativity is consequently improved. The final conclusion is that the freehand drawn images make a better link between author and observer, and at the same time the very movement and haptic perception of the hand elicit creativity. Nevertheless, the most recent advances in digitalising analogic dimensions through drawing tablets, have provided a new medium for freehand drawing, which can exploit the capacity of data handling of computers, time and effort saving, with the natural movement of using pencil and paper, ending up in an identical product. A wise usage of modern technology can therefore merge together the human factor of hand and brain reciprocal thrust with the fictitious world of the bits

The communication and recording of conceptual design information by the inclusion of visual data

This thesis reports the results of a three year, full-time research project investigating the generation and communication of product descriptions within the conceptual phase of the engineering design process. The research pays particular attention to the role played by the designer's sketch in communicating new product ideas. The investigation commences with a literature review of existing design process models (Chapter 2), which helps to define the area under investigation while presenting modern views of the process in relation to classic examples from established design research. Chapter 3 presents a literature review of the methods currently used to support communication of product descriptions. These methods of Specification are assessed and particular attention is given to new computer-based recording methods such as DOORS and Cradle. Suggestions for improving the efficiency of such models are put forward and the text-only bias of such systems is identified. This comparison of the existing systems thus identifies the research questions. Having identified the possible improvement to be gained by the incorporation of visual material in addition to the universal text description, Chapter 4 presents a literature review assessing the roles of the conceptual sketch in engineering design. As well as presenting views of drawing from philosophical, psychological and scientific standpoints, this section compares attempts made to support the engineer's sketching activity by computer means. This chapter concludes that efforts made to provide effective computer support of sketching by freehand methods are preferred to attempts made to replicate the process with current computer tools. The resulting research experiment, the methodology of which is described in Chapter 5, uses students from the final year of the Product Design Engineering course at Glasgow School of Art and the University of Glasgow. The main aim of the experiment is to identify means of including sketching within the kind of text-based support methods discussed in Chapter 3. It also observes the volume and pattern of information produced by sketch activity throughout the conceptual stages of the design process and aims to find methods which would enable sketches to indicate the general progress of a design. The findings are detailed in Chapter 6

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