Spherical tangible user interfaces in mixed reality

The popularity of virtual reality (VR) and augmented reality (AR) has grown rapidly in recent years, both in academia and commercial applications. This is rooted in technological advances and affordable head-mounted displays (HMDs). Whether in games or professional applications, HMDs allow for immersive audio-visual experiences that transport users to compelling digital worlds or convincingly augment the real world. However, as true to life as these experiences have become in a visual and auditory sense, the question remains how we can model interaction with these virtual environments in an equally natural way. Solutions providing intuitive tangible interaction would bear the potential to fundamentally make the mixed reality (MR) spectrum more accessible, especially for novice users. Research on tangible user interfaces (TUIs) has pursued this goal by coupling virtual to real-world objects. Tangible interaction has been shown to provide significant advantages for numerous use cases. Spherical tangible user interfaces (STUIs) present a special case of these devices, mainly due to their ability to fully embody any spherical virtual content. In general, spherical devices increasingly transition from mere technology demonstrators to usable multi-modal interfaces. For this dissertation, we explore the application of STUIs in MR environments primarily by comparing them to state-of-the-art input techniques in four different contexts. Thus, investigating the questions of embodiment, overall user performance, and the ability of STUIs relying on their shape alone to support complex interaction techniques. First, we examine how spherical devices can embody immersive visualizations. In an initial study, we test the practicality of a tracked sphere embodying three kinds of visualizations. We examine simulated multi-touch interaction on a spherical surface and compare two different sphere sizes to VR controllers. Results confirmed our prototype's viability and indicate improved pattern recognition and advantages for the smaller sphere. Second, to further substantiate VR as a prototyping technology, we demonstrate how a large tangible spherical display can be simulated in VR. We show how VR can fundamentally extend the capabilities of real spherical displays by adding physical rotation to a simulated multi-touch surface. After a first study evaluating the general viability of simulating such a display in VR, our second study revealed the superiority of a rotating spherical display. Third, we present a concept for a spherical input device for tangible AR (TAR). We show how such a device can provide basic object manipulation capabilities utilizing two different modes and compare it to controller techniques with increasing hardware complexity. Our results show that our button-less sphere-based technique is only outperformed by a mode-less controller variant that uses physical buttons and a touchpad. Fourth, to study the intrinsic problem of VR locomotion, we explore two opposing approaches: a continuous and a discrete technique. For the first, we demonstrate a spherical locomotion device supporting two different locomotion paradigms that propel a user's first-person avatar accordingly. We found that a position control paradigm applied to a sphere performed mostly superior in comparison to button-supported controller interaction. For discrete locomotion, we evaluate the concept of a spherical world in miniature (SWIM) used for avatar teleportation in a large virtual environment. Results showed that users subjectively preferred the sphere-based technique over regular controllers and on average, achieved lower task times and higher accuracy. To conclude the thesis, we discuss our findings, insights, and subsequent contribution to our central research questions to derive recommendations for designing techniques based on spherical input devices and an outlook on the future development of spherical devices in the mixed reality spectrum.Die Popularität von Virtual Reality (VR) und Augmented Reality (AR) hat in den letzten Jahren rasant zugenommen, sowohl im akademischen Bereich als auch bei kommerziellen Anwendungen. Dies ist in erster Linie auf technologische Fortschritte und erschwingliche Head-Mounted Displays (HMDs) zurückzuführen. Ob in Spielen oder professionellen Anwendungen, HMDs ermöglichen immersive audiovisuelle Erfahrungen, die uns in fesselnde digitale Welten versetzen oder die reale Welt überzeugend erweitern. Doch so lebensecht diese Erfahrungen in visueller und auditiver Hinsicht geworden sind, so bleibt doch die Frage, wie die Interaktion mit diesen virtuellen Umgebungen auf ebenso natürliche Weise gestaltet werden kann. Lösungen, die eine intuitive, greifbare Interaktion ermöglichen, hätten das Potenzial, das Spektrum der Mixed Reality (MR) fundamental zugänglicher zu machen, insbesondere für Unerfahrene. Die Forschung an Tangible User Interfaces (TUIs) hat dieses Ziel durch das Koppeln virtueller und realer Objekte verfolgt und so hat sich gezeigt, dass greifbare Interaktion für zahlreiche Anwendungsfälle signifikante Vorteile bietet. Spherical Tangible User Interfaces (STUIs) stellen einen Spezialfall von greifbaren Interfaces dar, insbesondere aufgrund ihrer Fähigkeit, beliebige sphärische virtuelle Inhalte vollständig verkörpern zu können. Generell entwickeln sich sphärische Geräte zunehmend von reinen Technologiedemonstratoren zu nutzbaren multimodalen Instrumenten, die auf eine breite Palette von Interaktionstechniken zurückgreifen können. Diese Dissertation untersucht primär die Anwendung von STUIs in MR-Umgebungen durch einen Vergleich mit State-of-the-Art-Eingabetechniken in vier verschiedenen Kontexten. Dies ermöglicht die Erforschung der Bedeutung der Verkörperung virtueller Objekte, der Benutzerleistung im Allgemeinen und der Fähigkeit von STUIs, die sich lediglich auf ihre Form verlassen, komplexe Interaktionstechniken zu unterstützen. Zunächst erforschen wir, wie sphärische Geräte immersive Visualisierungen verkörpern können. Eine erste Studie ergründet die Praxistauglichkeit einer einfach konstruierten, getrackten Kugel, die drei Arten von Visualisierungen verkörpert. Wir testen simulierte Multi-Touch-Interaktion auf einer sphärischen Oberfläche und vergleichen zwei Kugelgrößen mit VR-Controllern. Die Ergebnisse bestätigten die Praxistauglichkeit des Prototyps und deuten auf verbesserte Mustererkennung sowie Vorteile für die kleinere Kugel hin. Zweitens, um die Validität von VR als Prototyping-Technologie zu bekräftigen, demonstrieren wir, wie ein großes, anfassbares sphärisches Display in VR simuliert werden kann. Es zeigt sich, wie VR die Möglichkeiten realer sphärischer Displays substantiell erweitern kann, indem eine simulierte Multi-Touch-Oberfläche um die Fähigkeit der physischen Rotation ergänzt wird. Nach einer ersten Studie, die die generelle Machbarkeit der Simulation eines solchen Displays in VR evaluiert, zeigte eine zweite Studie die Überlegenheit des drehbaren sphärischen Displays. Drittens präsentiert diese Arbeit ein Konzept für ein sphärisches Eingabegerät für Tangible AR (TAR). Wir zeigen, wie ein solches Werkzeug grundlegende Fähigkeiten zur Objektmanipulation unter Verwendung von zwei verschiedenen Modi bereitstellen kann und vergleichen es mit Eingabetechniken deren Hardwarekomplexität zunehmend steigt. Unsere Ergebnisse zeigen, dass die kugelbasierte Technik, die ohne Knöpfe auskommt, nur von einer Controller-Variante übertroffen wird, die physische Knöpfe und ein Touchpad verwendet und somit nicht auf unterschiedliche Modi angewiesen ist. Viertens, um das intrinsische Problem der Fortbewegung in VR zu erforschen, untersuchen wir zwei gegensätzliche Ansätze: eine kontinuierliche und eine diskrete Technik. Für die erste präsentieren wir ein sphärisches Eingabegerät zur Fortbewegung, das zwei verschiedene Paradigmen unterstützt, die einen First-Person-Avatar entsprechend bewegen. Es zeigte sich, dass das Paradigma der direkten Positionssteuerung, angewandt auf einen Kugel-Controller, im Vergleich zu regulärer Controller-Interaktion, die zusätzlich auf physische Knöpfe zurückgreifen kann, meist besser abschneidet. Im Bereich der diskreten Fortbewegung evaluieren wir das Konzept einer kugelförmingen Miniaturwelt (Spherical World in Miniature, SWIM), die für die Avatar-Teleportation in einer großen virtuellen Umgebung verwendet werden kann. Die Ergebnisse zeigten eine subjektive Bevorzugung der kugelbasierten Technik im Vergleich zu regulären Controllern und im Durchschnitt eine schnellere Lösung der Aufgaben sowie eine höhere Genauigkeit. Zum Abschluss der Arbeit diskutieren wir unsere Ergebnisse, Erkenntnisse und die daraus resultierenden Beiträge zu unseren zentralen Forschungsfragen, um daraus Empfehlungen für die Gestaltung von Techniken auf Basis kugelförmiger Eingabegeräte und einen Ausblick auf die mögliche zukünftige Entwicklung sphärischer Eingabegräte im Mixed-Reality-Bereich abzuleiten

Configurable Input Devices for 3D Interaction using Optical Tracking

Three-dimensional interaction with virtual objects is one of the aspects that needs to be addressed in order to increase the usability and usefulness of virtual reality. Human beings have difficulties understanding 3D spatial relationships and manipulating 3D user interfaces, which require the control of multiple degrees of freedom simultaneously. Conventional interaction paradigms known from the desktop computer, such as the use of interaction devices as the mouse and keyboard, may be insufficient or even inappropriate for 3D spatial interaction tasks. The aim of the research in this thesis is to develop the technology required to improve 3D user interaction. This can be accomplished by allowing interaction devices to be constructed such that their use is apparent from their structure, and by enabling efficient development of new input devices for 3D interaction. The driving vision in this thesis is that for effective and natural direct 3D interaction the structure of an interaction device should be specifically tuned to the interaction task. Two aspects play an important role in this vision. First, interaction devices should be structured such that interaction techniques are as direct and transparent as possible. Interaction techniques define the mapping between interaction task parameters and the degrees of freedom of interaction devices. Second, the underlying technology should enable developers to rapidly construct and evaluate new interaction devices. The thesis is organized as follows. In Chapter 2, a review of the optical tracking field is given. The tracking pipeline is discussed, existing methods are reviewed, and improvement opportunities are identified. In Chapters 3 and 4 the focus is on the development of optical tracking techniques of rigid objects. The goal of the tracking method presented in Chapter 3 is to reduce the occlusion problem. The method exploits projection invariant properties of line pencil markers, and the fact that line features only need to be partially visible. In Chapter 4, the aim is to develop a tracking system that supports devices of arbitrary shapes, and allows for rapid development of new interaction devices. The method is based on subgraph isomorphism to identify point clouds. To support the development of new devices in the virtual environment an automatic model estimation method is used. Chapter 5 provides an analysis of three optical tracking systems based on different principles. The first system is based on an optimization procedure that matches the 3D device model points to the 2D data points that are detected in the camera images. The other systems are the tracking methods as discussed in Chapters 3 and 4. In Chapter 6 an analysis of various filtering and prediction methods is given. These techniques can be used to make the tracking system more robust against noise, and to reduce the latency problem. Chapter 7 focusses on optical tracking of composite input devices, i.e., input devices 197 198 Summary that consist of multiple rigid parts that can have combinations of rotational and translational degrees of freedom with respect to each other. Techniques are developed to automatically generate a 3D model of a segmented input device from motion data, and to use this model to track the device. In Chapter 8, the presented techniques are combined to create a configurable input device, which supports direct and natural co-located interaction. In this chapter, the goal of the thesis is realized. The device can be configured such that its structure reflects the parameters of the interaction task. In Chapter 9, the configurable interaction device is used to study the influence of spatial device structure with respect to the interaction task at hand. The driving vision of this thesis, that the spatial structure of an interaction device should match that of the task, is analyzed and evaluated by performing a user study. The concepts and techniques developed in this thesis allow researchers to rapidly construct and apply new interaction devices for 3D interaction in virtual environments. Devices can be constructed such that their spatial structure reflects the 3D parameters of the interaction task at hand. The interaction technique then becomes a transparent one-to-one mapping that directly mediates the functions of the device to the task. The developed configurable interaction devices can be used to construct intuitive spatial interfaces, and allow researchers to rapidly evaluate new device configurations and to efficiently perform studies on the relation between the spatial structure of devices and the interaction task

인간 기계 상호작용을 위한 강건하고 정확한 손동작 추적 기술 연구

학위논문(박사) -- 서울대학교대학원 : 공과대학 기계항공공학부, 2021.8. 이동준.Hand-based interface is promising for realizing intuitive, natural and accurate human machine interaction (HMI), as the human hand is main source of dexterity in our daily activities. For this, the thesis begins with the human perception study on the detection threshold of visuo-proprioceptive conflict (i.e., allowable tracking error) with or without cutantoues haptic feedback, and suggests tracking error specification for realistic and fluidic hand-based HMI. The thesis then proceeds to propose a novel wearable hand tracking module, which, to be compatible with the cutaneous haptic devices spewing magnetic noise, opportunistically employ heterogeneous sensors (IMU/compass module and soft sensor) reflecting the anatomical properties of human hand, which is suitable for specific application (i.e., finger-based interaction with finger-tip haptic devices). This hand tracking module however loses its tracking when interacting with, or being nearby, electrical machines or ferromagnetic materials. For this, the thesis presents its main contribution, a novel visual-inertial skeleton tracking (VIST) framework, that can provide accurate and robust hand (and finger) motion tracking even for many challenging real-world scenarios and environments, for which the state-of-the-art technologies are known to fail due to their respective fundamental limitations (e.g., severe occlusions for tracking purely with vision sensors; electromagnetic interference for tracking purely with IMUs (inertial measurement units) and compasses; and mechanical contacts for tracking purely with soft sensors). The proposed VIST framework comprises a sensor glove with multiple IMUs and passive visual markers as well as a head-mounted stereo camera; and a tightly-coupled filtering-based visual-inertial fusion algorithm to estimate the hand/finger motion and auto-calibrate hand/glove-related kinematic parameters simultaneously while taking into account the hand anatomical constraints. The VIST framework exhibits good tracking accuracy and robustness, affordable material cost, light hardware and software weights, and ruggedness/durability even to permit washing. Quantitative and qualitative experiments are also performed to validate the advantages and properties of our VIST framework, thereby, clearly demonstrating its potential for real-world applications.손 동작을 기반으로 한 인터페이스는 인간-기계 상호작용 분야에서 직관성, 몰입감, 정교함을 제공해줄 수 있어 많은 주목을 받고 있고, 이를 위해 가장 필수적인 기술 중 하나가 손 동작의 강건하고 정확한 추적 기술 이다. 이를 위해 본 학위논문에서는 먼저 사람 인지의 관점에서 손 동작 추적 오차의 인지 범위를 규명한다. 이 오차 인지 범위는 새로운 손 동작 추적 기술 개발 시 중요한 설계 기준이 될 수 있어 이를 피험자 실험을 통해 정량적으로 밝히고, 특히 손끝 촉각 장비가 있을때 이 인지 범위의 변화도 밝힌다. 이를 토대로, 촉각 피드백을 주는 것이 다양한 인간-기계 상호작용 분야에서 널리 연구되어 왔으므로, 먼저 손끝 촉각 장비와 함께 사용할 수 있는 손 동작 추적 모듈을 개발한다. 이 손끝 촉각 장비는 자기장 외란을 일으켜 착용형 기술에서 흔히 사용되는 지자기 센서를 교란하는데, 이를 적절한 사람 손의 해부학적 특성과 관성 센서/지자기 센서/소프트 센서의 적절한 활용을 통해 해결한다. 이를 확장하여 본 논문에서는, 촉각 장비 착용 시 뿐 아니라 모든 장비 착용 / 환경 / 물체와의 상호작용 시에도 사용 가능한 새로운 손 동작 추적 기술을 제안한다. 기존의 손 동작 추적 기술들은 가림 현상 (영상 기반 기술), 지자기 외란 (관성/지자기 센서 기반 기술), 물체와의 접촉 (소프트 센서 기반 기술) 등으로 인해 제한된 환경에서 밖에 사용하지 못한다. 이를 위해 많은 문제를 일으키는 지자기 센서 없이 상보적인 특성을 지니는 관성 센서와 영상 센서를 융합하고, 이때 작은 공간에 다 자유도의 움직임을 갖는 손 동작을 추적하기 위해 다수의 구분되지 않는 마커들을 사용한다. 이 마커의 구분 과정 (correspondence search)를 위해 기존의 약결합 (loosely-coupled) 기반이 아닌 강결합 (tightly-coupled 기반 센서 융합 기술을 제안하고, 이를 통해 지자기 센서 없이 정확한 손 동작이 가능할 뿐 아니라 착용형 센서들의 정확성/편의성에 문제를 일으키던 센서 부착 오차 / 사용자의 손 모양 등을 자동으로 정확히 보정한다. 이 제안된 영상-관성 센서 융합 기술 (Visual-Inertial Skeleton Tracking (VIST)) 의 뛰어난 성능과 강건성이 다양한 정량/정성 실험을 통해 검증되었고, 이는 VIST의 다양한 일상환경에서 기존 시스템이 구현하지 못하던 손 동작 추적을 가능케 함으로써, 많은 인간-기계 상호작용 분야에서의 가능성을 보여준다.1 Introduction 1 1.1. Motivation 1 1.2. Related Work 5 1.3. Contribution 12 2 Detection Threshold of Hand Tracking Error 16 2.1. Motivation 16 2.2. Experimental Environment 20 2.2.1. Hardware Setup 21 2.2.2. Virtual Environment Rendering 23 2.2.3. HMD Calibration 23 2.3. Identifying the Detection Threshold of Tracking Error 26 2.3.1. Experimental Setup 27 2.3.2. Procedure 27 2.3.3. Experimental Result 31 2.4. Enlarging the Detection Threshold of Tracking Error by Haptic Feedback 31 2.4.1. Experimental Setup 31 2.4.2. Procedure 32 2.4.3. Experimental Result 34 2.5. Discussion 34 3 Wearable Finger Tracking Module for Haptic Interaction 38 3.1. Motivation 38 3.2. Development of Finger Tracking Module 42 3.2.1. Hardware Setup 42 3.2.2. Tracking algorithm 45 3.2.3. Calibration method 48 3.3. Evaluation for VR Haptic Interaction Task 50 3.3.1. Quantitative evaluation of FTM 50 3.3.2. Implementation of Wearable Cutaneous Haptic Interface 51 3.3.3. Usability evaluation for VR peg-in-hole task 53 3.4. Discussion 57 4 Visual-Inertial Skeleton Tracking for Human Hand 59 4.1. Motivation 59 4.2. Hardware Setup and Hand Models 62 4.2.1. Human Hand Model 62 4.2.2. Wearable Sensor Glove 62 4.2.3. Stereo Camera 66 4.3. Visual Information Extraction 66 4.3.1. Marker Detection in Raw Images 68 4.3.2. Cost Function for Point Matching 68 4.3.3. Left-Right Stereo Matching 69 4.4. IMU-Aided Correspondence Search 72 4.5. Filtering-based Visual-Inertial Sensor Fusion 76 4.5.1. EKF States for Hand Tracking and Auto-Calibration 78 4.5.2. Prediction with IMU Information 79 4.5.3. Correction with Visual Information 82 4.5.4. Correction with Anatomical Constraints 84 4.6. Quantitative Evaluation for Free Hand Motion 87 4.6.1. Experimental Setup 87 4.6.2. Procedure 88 4.6.3. Experimental Result 90 4.7. Quantitative and Comparative Evaluation for Challenging Hand Motion 95 4.7.1. Experimental Setup 95 4.7.2. Procedure 96 4.7.3. Experimental Result 98 4.7.4. Performance Comparison with Existing Methods for Challenging Hand Motion 101 4.8. Qualitative Evaluation for Real-World Scenarios 105 4.8.1. Visually Complex Background 105 4.8.2. Object Interaction 106 4.8.3. Wearing Fingertip Cutaneous Haptic Devices 109 4.8.4. Outdoor Environment 111 4.9. Discussion 112 5 Conclusion 116 References 124 Abstract (in Korean) 139 Acknowledgment 141박

Stereoscopic bimanual interaction for 3D visualization

Virtual Environments (VE) are being widely used in various research fields for several decades such as 3D visualization, education, training and games. VEs have the potential to enhance the visualization and act as a general medium for human-computer interaction (HCI). However, limited research has evaluated virtual reality (VR) display technologies, monocular and binocular depth cues, for human depth perception of volumetric (non-polygonal) datasets. In addition, a lack of standardization of three-dimensional (3D) user interfaces (UI) makes it challenging to interact with many VE systems. To address these issues, this dissertation focuses on evaluation of effects of stereoscopic and head-coupled displays on depth judgment of volumetric dataset. It also focuses on evaluation of a two-handed view manipulation techniques which support simultaneous 7 degree-of-freedom (DOF) navigation (x,y,z + yaw,pitch,roll + scale) in a multi-scale virtual environment (MSVE). Furthermore, this dissertation evaluates auto-adjustment of stereo view parameters techniques for stereoscopic fusion problems in a MSVE. Next, this dissertation presents a bimanual, hybrid user interface which combines traditional tracking devices with computer-vision based "natural" 3D inputs for multi-dimensional visualization in a semi-immersive desktop VR system. In conclusion, this dissertation provides a guideline for research design for evaluating UI and interaction techniques

An Immersive Telepresence System using RGB-D Sensors and Head Mounted Display

We present a tele-immersive system that enables people to interact with each other in a virtual world using body gestures in addition to verbal communication. Beyond the obvious applications, including general online conversations and gaming, we hypothesize that our proposed system would be particularly beneficial to education by offering rich visual contents and interactivity. One distinct feature is the integration of egocentric pose recognition that allows participants to use their gestures to demonstrate and manipulate virtual objects simultaneously. This functionality enables the instructor to ef- fectively and efficiently explain and illustrate complex concepts or sophisticated problems in an intuitive manner. The highly interactive and flexible environment can capture and sustain more student attention than the traditional classroom setting and, thus, delivers a compelling experience to the students. Our main focus here is to investigate possible solutions for the system design and implementation and devise strategies for fast, efficient computation suitable for visual data processing and network transmission. We describe the technique and experiments in details and provide quantitative performance results, demonstrating our system can be run comfortably and reliably for different application scenarios. Our preliminary results are promising and demonstrate the potential for more compelling directions in cyberlearning.Comment: IEEE International Symposium on Multimedia 201

Contactless Haptic Display Through Magnetic Field Control

Haptic rendering enables people to touch, perceive, and manipulate virtual objects in a virtual environment. Using six cascaded identical hollow disk electromagnets and a small permanent magnet attached to an operator's finger, this paper proposes and develops an untethered haptic interface through magnetic field control. The concentric hole inside the six cascaded electromagnets provides the workspace, where the 3D position of the permanent magnet is tracked with a Microsoft Kinect sensor. The driving currents of six cascaded electromagnets are calculated in real-time for generating the desired magnetic force. Offline data from an FEA (finite element analysis) based simulation, determines the relationship between the magnetic force, the driving currents, and the position of the permanent magnet. A set of experiments including the virtual object recognition experiment, the virtual surface identification experiment, and the user perception evaluation experiment were conducted to demonstrate the proposed system, where Microsoft HoloLens holographic glasses are used for visual rendering. The proposed magnetic haptic display leads to an untethered and non-contact interface for natural haptic rendering applications, which overcomes the constraints of mechanical linkages in tool-based traditional haptic devices