HOLOGRAPHICS: Combining Holograms with Interactive Computer Graphics

Among all imaging techniques that have been invented throughout the last decades, computer graphics is one of the most successful tools today. Many areas in science, entertainment, education, and engineering would be unimaginable without the aid of 2D or 3D computer graphics. The reason for this success story might be its interactivity, which is an important property that is still not provided efficiently by competing technologies – such as holography. While optical holography and digital holography are limited to presenting a non-interactive content, electroholography or computer generated holograms (CGH) facilitate the computer-based generation and display of holograms at interactive rates [2,3,29,30]. Holographic fringes can be computed by either rendering multiple perspective images, then combining them into a stereogram [4], or simulating the optical interference and calculating the interference pattern [5]. Once computed, such a system dynamically visualizes the fringes with a holographic display. Since creating an electrohologram requires processing, transmitting, and storing a massive amount of data, today’s computer technology still sets the limits for electroholography. To overcome some of these performance issues, advanced reduction and compression methods have been developed that create truly interactive electroholograms. Unfortunately, most of these holograms are relatively small, low resolution, and cover only a small color spectrum. However, recent advances in consumer graphics hardware may reveal potential acceleration possibilities that can overcome these limitations [6]. In parallel to the development of computer graphics and despite their non-interactivity, optical and digital holography have created new fields, including interferometry, copy protection, data storage, holographic optical elements, and display holograms. Especially display holography has conquered several application domains. Museum exhibits often use optical holograms because they can present 3D objects with almost no loss in visual quality. In contrast to most stereoscopic or autostereoscopic graphics displays, holographic images can provide all depth cues—perspective, binocular disparity, motion parallax, convergence, and accommodation—and theoretically can be viewed simultaneously from an unlimited number of positions. Displaying artifacts virtually removes the need to build physical replicas of the original objects. In addition, optical holograms can be used to make engineering, medical, dental, archaeological, and other recordings—for teaching, training, experimentation and documentation. Archaeologists, for example, use optical holograms to archive and investigate ancient artifacts [7,8]. Scientists can use hologram copies to perform their research without having access to the original artifacts or settling for inaccurate replicas. Optical holograms can store a massive amount of information on a thin holographic emulsion. This technology can record and reconstruct a 3D scene with almost no loss in quality. Natural color holographic silver halide emulsion with grain sizes of 8nm is today’s state-of-the-art [14]. Today, computer graphics and raster displays offer a megapixel resolution and the interactive rendering of megabytes of data. Optical holograms, however, provide a terapixel resolution and are able to present an information content in the range of terabytes in real-time. Both are dimensions that will not be reached by computer graphics and conventional displays within the next years – even if Moore’s law proves to hold in future. Obviously, one has to make a decision between interactivity and quality when choosing a display technology for a particular application. While some applications require high visual realism and real-time presentation (that cannot be provided by computer graphics), others depend on user interaction (which is not possible with optical and digital holograms). Consequently, holography and computer graphics are being used as tools to solve individual research, engineering, and presentation problems within several domains. Up until today, however, these tools have been applied separately. The intention of the project which is summarized in this chapter is to combine both technologies to create a powerful tool for science, industry and education. This has been referred to as HoloGraphics. Several possibilities have been investigated that allow merging computer generated graphics and holograms [1]. The goal is to combine the advantages of conventional holograms (i.e. extremely high visual quality and realism, support for all depth queues and for multiple observers at no computational cost, space efficiency, etc.) with the advantages of today’s computer graphics capabilities (i.e. interactivity, real-time rendering, simulation and animation, stereoscopic and autostereoscopic presentation, etc.). The results of these investigations are presented in this chapter

Multi-touch Detection and Semantic Response on Non-parametric Rear-projection Surfaces

The ability of human beings to physically touch our surroundings has had a profound impact on our daily lives. Young children learn to explore their world by touch; likewise, many simulation and training applications benefit from natural touch interactivity. As a result, modern interfaces supporting touch input are ubiquitous. Typically, such interfaces are implemented on integrated touch-display surfaces with simple geometry that can be mathematically parameterized, such as planar surfaces and spheres; for more complicated non-parametric surfaces, such parameterizations are not available. In this dissertation, we introduce a method for generalizable optical multi-touch detection and semantic response on uninstrumented non-parametric rear-projection surfaces using an infrared-light-based multi-camera multi-projector platform. In this paradigm, touch input allows users to manipulate complex virtual 3D content that is registered to and displayed on a physical 3D object. Detected touches trigger responses with specific semantic meaning in the context of the virtual content, such as animations or audio responses. The broad problem of touch detection and response can be decomposed into three major components: determining if a touch has occurred, determining where a detected touch has occurred, and determining how to respond to a detected touch. Our fundamental contribution is the design and implementation of a relational lookup table architecture that addresses these challenges through the encoding of coordinate relationships among the cameras, the projectors, the physical surface, and the virtual content. Detecting the presence of touch input primarily involves distinguishing between touches (actual contact events) and hovers (near-contact proximity events). We present and evaluate two algorithms for touch detection and localization utilizing the lookup table architecture. One of the algorithms, a bounded plane sweep, is additionally able to estimate hover-surface distances, which we explore for interactions above surfaces. The proposed method is designed to operate with low latency and to be generalizable. We demonstrate touch-based interactions on several physical parametric and non-parametric surfaces, and we evaluate both system accuracy and the accuracy of typical users in touching desired targets on these surfaces. In a formative human-subject study, we examine how touch interactions are used in the context of healthcare and present an exploratory application of this method in patient simulation. A second study highlights the advantages of touch input on content-matched physical surfaces achieved by the proposed approach, such as decreases in induced cognitive load, increases in system usability, and increases in user touch performance. In this experiment, novice users were nearly as accurate when touching targets on a 3D head-shaped surface as when touching targets on a flat surface, and their self-perception of their accuracy was higher

Pictures in Your Mind: Using Interactive Gesture-Controlled Reliefs to Explore Art

Tactile reliefs offer many benefits over the more classic raised line drawings or tactile diagrams, as depth, 3D shape, and surface textures are directly perceivable. Although often created for blind and visually impaired (BVI) people, a wider range of people may benefit from such multimodal material. However, some reliefs are still difficult to understand without proper guidance or accompanying verbal descriptions, hindering autonomous exploration. In this work, we present a gesture-controlled interactive audio guide (IAG) based on recent low-cost depth cameras that can be operated directly with the hands on relief surfaces during tactile exploration. The interactively explorable, location-dependent verbal and captioned descriptions promise rapid tactile accessibility to 2.5D spatial information in a home or education setting, to online resources, or as a kiosk installation at public places. We present a working prototype, discuss design decisions, and present the results of two evaluation studies: the first with 13 BVI test users and the second follow-up study with 14 test users across a wide range of people with differences and difficulties associated with perception, memory, cognition, and communication. The participant-led research method of this latter study prompted new, significant and innovative developments

Through the combining glass

Reflective optical combiners like beam splitters and two way mirrors are used in AR to overlap digital contents on the users' hands or bodies. Augmentations are usually unidirectional, either reflecting virtual contents on the user's body (Situated Augmented Reality) or augmenting user's reflections with digital contents (AR mirrors). But many other novel possibilities remain unexplored. For example, users' hands, reflected inside a museum AR cabinet, can allow visitors to interact with the artifacts exhibited. Projecting on the user's hands as their reflection cuts through the objects can be used to reveal objects' internals. Augmentations from both sides are blended by the combiner, so they are consistently seen by any number of users, independently of their location or, even, the side of the combiner through which they are looking. This paper explores the potential of optical combiners to merge the space in front and behind them. We present this design space, identify novel augmentations/interaction opportunities and explore the design space using three prototypes

Vision-Based Finger Detection, Tracking, and Event Identification Techniques for Multi-Touch Sensing and Display Systems

This study presents efficient vision-based finger detection, tracking, and event identification techniques and a low-cost hardware framework for multi-touch sensing and display applications. The proposed approach uses a fast bright-blob segmentation process based on automatic multilevel histogram thresholding to extract the pixels of touch blobs obtained from scattered infrared lights captured by a video camera. The advantage of this automatic multilevel thresholding approach is its robustness and adaptability when dealing with various ambient lighting conditions and spurious infrared noises. To extract the connected components of these touch blobs, a connected-component analysis procedure is applied to the bright pixels acquired by the previous stage. After extracting the touch blobs from each of the captured image frames, a blob tracking and event recognition process analyzes the spatial and temporal information of these touch blobs from consecutive frames to determine the possible touch events and actions performed by users. This process also refines the detection results and corrects for errors and occlusions caused by noise and errors during the blob extraction process. The proposed blob tracking and touch event recognition process includes two phases. First, the phase of blob tracking associates the motion correspondence of blobs in succeeding frames by analyzing their spatial and temporal features. The touch event recognition process can identify meaningful touch events based on the motion information of touch blobs, such as finger moving, rotating, pressing, hovering, and clicking actions. Experimental results demonstrate that the proposed vision-based finger detection, tracking, and event identification system is feasible and effective for multi-touch sensing applications in various operational environments and conditions

Interaktion mit Medienfassaden : Design und Implementierung interaktiver Systeme für große urbane Displays

Media facades are a prominent example of the digital augmentation of urban spaces. They denote the concept of turning the surface of a building into a large-scale urban screen. Due to their enormous size, they require interaction at a distance and they have a high level of visibility. Additionally, they are situated in a highly dynamic urban environment with rapidly changing conditions, which results in settings that are neither comparable, nor reproducible. Altogether, this makes the development of interactive media facade installations a challenging task. This thesis investigates the design of interactive installations for media facades holistically. A theoretical analysis of the design space for interactive installations for media facades is conducted to derive taxonomies to put media facade installations into context. Along with this, a set of observations and guidelines is provided to derive properties of the interaction from the technical characteristics of an interactive media facade installation. This thesis further provides three novel interaction techniques addressing the form factor and resolution of the facade, without the need for additionally instrumenting the space around the facades. The thesis contributes to the design of interactive media facade installations by providing a generalized media facade toolkit for rapid prototyping and simulating interactive media facade installations, independent of the media facade’s size, form factor, technology and underlying hardware.Die wachsende Zahl an Medienfassenden ist ein eindrucksvolles Beispiel für die digitale Erweiterung des öffentlichen Raums. Medienfassaden beschreiben die Möglichkeit, die Oberfläche eines Gebäudes in ein digitales Display zu wandeln. Ihre Größe erfordert Interaktion aus einer gewissen Distanz und führt zu einer großen Sichtbarkeit der dargestellten Inhalte. Medienfassaden-Installationen sind bedingt durch ihre dynamische Umgebung nur schwerlich vergleich- und reproduzierbar. All dies macht die Entwicklung von Installationen für Medienfassaden zu einer großen Herausforderung. Diese Arbeit beschäftigt sich mit der Entwicklung interaktiver Installationen für Medienfassaden. Es wird eine theoretische Analyse des Design-Spaces interaktiver Medienfassaden-Installationen durchgeführt und es werden Taxonomien entwickelt, die Medienfassaden-Installationen in Bezug zueinander setzen. In diesem Zusammenhang werden ausgehend von den technischen Charakteristika Eigenschaften der Interaktion erarbeitet. Zur Interaktion mit Medienfassaden werden drei neue Interaktionstechniken vorgestellt, die Form und Auflösung der Fassade berücksichtigen, ohne notwendigerweise die Umgebung der Fassade zu instrumentieren. Die Ergebnisse dieser Arbeit verbessern darüber hinaus die Entwicklung von Installationen für Medienfassaden, indem ein einheitliches Medienfassaden-Toolkit zum Rapid-Prototyping und zur Simulation interaktiver Installationen vorgestellt wird, das unabhängig von Größe und Form der Medienfassade sowie unabhängig von der verwendeten Technologie und der zugrunde liegenden Hardware ist

Interacting "Through the Display"

The increasing availability of displays at lower costs has led to a proliferation of such in our everyday lives. Additionally, mobile devices are ready to hand and have been proposed as interaction devices for external screens. However, only their input mechanism was taken into account without considering three additional factors in environments hosting several displays: first, a connection needs to be established to the desired target display (modality). Second, screens in the environment may be re-arranged (flexibility). And third, displays may be out of the user’s reach (distance). In our research we aim to overcome the problems resulting from these characteristics. The overall goal is a new interaction model that allows for (1) a non-modal connection mechanism for impromptu use on various displays in the environment, (2) interaction on and across displays in highly flexible environments, and (3) interacting at variable distances. In this work we propose a new interaction model called through the display interaction which enables users to interact with remote content on their personal device in an absolute and direct fashion. To gain a better understanding of the effects of the additional characteristics, we implemented two prototypes each of which investigates a different distance to the target display: LucidDisplay allows users to place their mobile device directly on top of a larger external screen. MobileVue on the other hand enables users to interact with an external screen at a distance. In each of these prototypes we analyzed their effects on the remaining two criteria – namely the modality of the connection mechanism as well as the flexibility of the environment. With the findings gained in this initial phase we designed Shoot & Copy, a system that allows the detection of screens purely based on their visual content. Users aim their personal device’s camera at the target display which then appears in live video shown in the viewfinder. To select an item, users take a picture which is analyzed to determine the targeted region. We further extended this approach to multiple displays by using a centralized component serving as gateway to the display environment. In Tap & Drop we refined this prototype to support real-time feedback. Instead of taking pictures, users can now aim their mobile device at the display resulting and start interacting immediately. In doing so, we broke the rigid sequential interaction of content selection and content manipulation. Both prototypes allow for (1) connections in a non-modal way (i.e., aim at the display and start interacting with it) from the user’s point of view and (2) fully flexible environments (i.e., the mobile device tracks itself with respect to displays in the environment). However, the wide-angle lenses and thus greater field of views of current mobile devices still do not allow for variable distances. In Touch Projector, we overcome this limitation by introducing zooming in combination with temporarily freezing the video image. Based on our extensions to taxonomy of mobile device interaction on external displays, we created a refined model of interacting through the display for mobile use. It enables users to interact impromptu without explicitly establishing a connection to the target display (non-modal). As the mobile device tracks itself with respect to displays in the environment, the model further allows for full flexibility of the environment (i.e., displays can be re-arranged without affecting on the interaction). And above all, users can interact with external displays regardless of their actual size at variable distances without any loss of accuracy.Die steigende Verfügbarkeit von Bildschirmen hat zu deren Verbreitung in unserem Alltag geführt. Ferner sind mobile Geräte immer griffbereit und wurden bereits als Interaktionsgeräte für zusätzliche Bildschirme vorgeschlagen. Es wurden jedoch nur Eingabemechanismen berücksichtigt ohne näher auf drei weitere Faktoren in Umgebungen mit mehreren Bildschirmen einzugehen: (1) Beide Geräte müssen verbunden werden (Modalität). (2) Bildschirme können in solchen Umgebungen umgeordnet werden (Flexibilität). (3) Monitore können außer Reichweite sein (Distanz). Wir streben an, die Probleme, die durch diese Eigenschaften auftreten, zu lösen. Das übergeordnete Ziel ist ein Interaktionsmodell, das einen nicht-modalen Verbindungsaufbau für spontane Verwendung von Bildschirmen in solchen Umgebungen, (2) Interaktion auf und zwischen Bildschirmen in flexiblen Umgebungen, und (3) Interaktionen in variablen Distanzen erlaubt. Wir stellen ein Modell (Interaktion durch den Bildschirm) vor, mit dem Benutzer mit entfernten Inhalten in direkter und absoluter Weise auf ihrem Mobilgerät interagieren können. Um die Effekte der hinzugefügten Charakteristiken besser zu verstehen, haben wir zwei Prototypen für unterschiedliche Distanzen implementiert: LucidDisplay erlaubt Benutzern ihr mobiles Gerät auf einen größeren, sekundären Bildschirm zu legen. Gegensätzlich dazu ermöglicht MobileVue die Interaktion mit einem zusätzlichen Monitor in einer gewissen Entfernung. In beiden Prototypen haben wir dann die Effekte der verbleibenden zwei Kriterien (d.h. Modalität des Verbindungsaufbaus und Flexibilität der Umgebung) analysiert. Mit den in dieser ersten Phase erhaltenen Ergebnissen haben wir Shoot & Copy entworfen. Dieser Prototyp erlaubt die Erkennung von Bildschirmen einzig über deren visuellen Inhalt. Benutzer zeigen mit der Kamera ihres Mobilgeräts auf einen Bildschirm dessen Inhalt dann in Form von Video im Sucher dargestellt wird. Durch die Aufnahme eines Bildes (und der darauf folgenden Analyse) wird Inhalt ausgewählt. Wir haben dieses Konzept zudem auf mehrere Bildschirme erweitert, indem wir eine zentrale Instanz verwendet haben, die als Schnittstelle zur Umgebung agiert. Mit Tap & Drop haben wir den Prototyp verfeinert, um Echtzeit-Feedback zu ermöglichen. Anstelle der Bildaufnahme können Benutzer nun ihr mobiles Gerät auf den Bildschirm richten und sofort interagieren. Dadurch haben wir die strikt sequentielle Interaktion (Inhalt auswählen und Inhalt manipulieren) aufgebrochen. Beide Prototypen erlauben bereits nicht-modale Verbindungsmechanismen in flexiblen Umgebungen. Die in heutigen Mobilgeräten verwendeten Weitwinkel-Objektive erlauben jedoch nach wie vor keine variablen Distanzen. Mit Touch Projector beseitigen wir diese Einschränkung, indem wir Zoomen in Kombination mit einer vorübergehenden Pausierung des Videos im Sucher einfügen. Basierend auf den Erweiterungen der Klassifizierung von Interaktionen mit zusätzlichen Bildschirmen durch mobile Geräte haben wir ein verbessertes Modell (Interaktion durch den Bildschirm) erstellt. Es erlaubt Benutzern spontan zu interagieren, ohne explizit eine Verbindung zum zweiten Bildschirm herstellen zu müssen (nicht-modal). Da das mobile Gerät seinen räumlichen Bezug zu allen Bildschirmen selbst bestimmt, erlaubt unser Modell zusätzlich volle Flexibilität in solchen Umgebungen. Darüber hinaus können Benutzer mit zusätzlichen Bildschirmen (unabhängig von deren Größe) in variablen Entfernungen interagieren

Freeform 3D interactions in everyday environments

PhD ThesisPersonal computing is continuously moving away from traditional input using mouse and keyboard, as new input technologies emerge. Recently, natural user interfaces (NUI) have led to interactive systems that are inspired by our physical interactions in the real-world, and focus on enabling dexterous freehand input in 2D or 3D. Another recent trend is Augmented Reality (AR), which follows a similar goal to further reduce the gap between the real and the virtual, but predominately focuses on output, by overlaying virtual information onto a tracked real-world 3D scene. Whilst AR and NUI technologies have been developed for both immersive 3D output as well as seamless 3D input, these have mostly been looked at separately. NUI focuses on sensing the user and enabling new forms of input; AR traditionally focuses on capturing the environment around us and enabling new forms of output that are registered to the real world. The output of NUI systems is mainly presented on a 2D display, while the input technologies for AR experiences, such as data gloves and body-worn motion trackers are often uncomfortable and restricting when interacting in the real world. NUI and AR can be seen as very complimentary, and bringing these two fields together can lead to new user experiences that radically change the way we interact with our everyday environments. The aim of this thesis is to enable real-time, low latency, dexterous input and immersive output without heavily instrumenting the user. The main challenge is to retain and to meaningfully combine the positive qualities that are attributed to both NUI and AR systems. I review work in the intersecting research fields of AR and NUI, and explore freehand 3D interactions with varying degrees of expressiveness, directness and mobility in various physical settings. There a number of technical challenges that arise when designing a mixed NUI/AR system, which I will address is this work: What can we capture, and how? How do we represent the real in the virtual? And how do we physically couple input and output? This is achieved by designing new systems, algorithms, and user experiences that explore the combination of AR and NUI