Courbure discrète : théorie et applications

International audienceThe present volume contains the proceedings of the 2013 Meeting on discrete curvature, held at CIRM, Luminy, France. The aim of this meeting was to bring together researchers from various backgrounds, ranging from mathematics to computer science, with a focus on both theory and applications. With 27 invited talks and 8 posters, the conference attracted 70 researchers from all over the world. The challenge of finding a common ground on the topic of discrete curvature was met with success, and these proceedings are a testimony of this wor

NASA/American Society for Engineering Education (ASEE) Summer Faculty Fellowship Program 1989

Since 1964, NASA has supported a program of summer faculty fellowships for engineering and science educators. The objectives are: to further the professional knowledge of qualified engineering and science faculty; to stimulate and exchange ideas between participants and NASA; to enrich and refresh the research and teachning activities of participants' institutions; and to contribute to the research objectives of the NASA center. College or university faculty members will be appointed as Research Fellows to spend 10 weeks in cooperative research and study at the NASA Langley Research Center. The Fellow will devote approximately 90 percent of the time to a research problem and the remaining time to a study program. The study program will consist of lecture and seminars on topics of interest or that are directly relevant to the Fellows' research topic

New acquisition techniques for real objects and light sources in computer graphics

Accurate representations of objects and light sources in a scene model are a crucial prerequisite for realistic image synthesis using computer graphics techniques. This thesis presents techniques for the effcient acquisition of real world objects and real world light sources, as well as an assessment of the quality of the acquired models. Making use of color management techniques, we setup an appearance reproduction pipeline that ensures best-possible reproduction of local light reflection with the available input and output devices. We introduce a hierarchical model for the subsurface light transport in translucent objects, derive an acquisition methodology, and acquire models of several translucent objects that can be rendered interactively. Since geometry models of real world objects are often acquired using 3D range scanners, we also present a method based on the concept of modulation transfer functions to evaluate their accuracy. In order to illuminate a scene with realistic light sources, we propose a method to acquire a model of the near-field emission pattern of a light source with optical prefiltering. We apply this method to several light sources with different emission characteristics and demonstrate the integration of the acquired models into both, global illumination as well as hardware-accelerated rendering systems.Exakte Repräsentationen der Objekte und Lichtquellen in einem Modell einer Szene sind eine unerlässliche Voraussetzung für die realistische Bilderzeugung mit Techniken der Computergraphik. Diese Dissertation beschäftigt sich mit der effizienten Digitalisierung von realen Objekten und realen Lichtquellen. Dabei werden sowohl neue Digitalisierungstechniken als auch Methoden zur Bestimmung der Qualität der erzeugten Modelle vorgestellt. Wir schlagen eine Verarbeitungskette zur Digitalisierung und Wiedergabe der Farbe und Spekularität von Objekten vor, die durch Ausnutzung von Farbmanagementtechniken eine bestmögliche Wiedergabe des Objekts unter Verwendung der gegebenen Ein- und Ausgabegeräte ermöglicht. Wir führen weiterhin ein hierarchisches Modell für den Lichttransport im Inneren von Objekten aus durchscheinenden Materialien sowie eine zugehörige Akquisitionsmethode ein und digitalisieren mehrere reale Objekte. Die dabei erzeugten Modelle können in Echtzeit angezeigt werden. Die Geometrie realer Objekte spielt eine entscheidende Rolle in vielen Anwendungen und wird oftmals unter Verwendung von 3D Scannern digitalisiert. Wir entwickeln daher eine Methode zur Bestimmung der Genauigkeit eines 3D Scanners, die auf dem Konzept der Modulationstransferfunktion basiert. Um eine Szene mit realen Lichtquellen beleuchten zu können, schlagen wir ferner eine Methode zur Erfassung der Nahfeldabstrahlung eine Lichtquelle vor, bei der vor der Digitalisierung ein optischer Filterungsschritt durchgeführt wird. Wir wenden diese Methode zur Digitalisierung mehrerer Lichtquellen mit unterschiedlichen Abstrahlcharakteristika an und zeigen auf, wie die dabei erzeugten Modelle in globalen Beleuchtungsberechnungen sowie bei der Bildsynthese mittels moderner Graphikkarten verwendet werden können

Object tracking in augmented reality remote access laboratories without fiducial markers

Remote Access Laboratories provide students with access to learning resources without the need to be in-situ (with the assets). The technology endows users with access to physical experiments anywhere and anytime, while also minimising or distributing the cost of operation for expensive laboratory equipment. Augmented Reality is a technology which provides interactive sensory feedback to users. The user experiences reality through a computer-based user interface with additional computer-generated information in the form applicable to the targeted senses. Recent advances in high definition video capture devices, video screens and mobile computers have driven resurgence in mainstream Augmented Reality technologies. Lower cost and greater processing power of microprocessors and memory place the resources in the hands of developers and users alike, allowing education institutes to invest in technologies that enhance the delivery of course content. This increase in pedagogical resources has already allowed the phenomenon of education at a distance to reach students from a wide range of demographics, improving access and outcomes in multiple disciplines. Incorporating Augmented Reality into Remote Access Laboratories resources has the benefit of improving overall user immersion into the remote experiment, thus improving student engagement and understanding of the delivered material. Visual implementations of Augmented Reality rely on providing the user with seamless integration of the current environment (through mobile device, desktop PC, or heads up display) with computer generated artificial visual artefacts. Virtual objects must appear in context to the current environment, and respond in a realistic period, or else the user suffers from a disjointed and confusing blend of real and virtual information. Understanding and interacting with the visual scene is controlled through Computer Vision algorithms, and are crucial in ensuring that the AR systems co-operate with the data discovered through the systems. While Augmented Reality has begun to expand in the educational environment, currently, there is still very little overlap of Augmented Reality technologies with Remote Access Laboratories. This research has investigated Computer Vision models that support Augmented Reality technologies such that live video streams from Remote Laboratories are enhanced by synthetic overlays pertinent to the experiments. Orientation of synthetic visual overlays requires knowledge of key reference points, often performed by fiducial markers. Removing the equipment’s need for fiducial markers and a priori knowledge simplifies and accelerates the uptake and expansion of the technology. These works uncover hybrid Computer Vision models which require no prior knowledge of the laboratory environment, including no fiducial markers or tags to track important objects and references. Developed models derive all relevant data from the live video stream and require no previous knowledge regarding the configuration of the physical scene. The new image analysis paradigms, (Two-Dimensional Colour Histograms and Neighbourhood Gradient Signature) improve the current state of markerless tracking through the unique attributes discovered within the sequential video frames. Novel methods are also established, with which to assess and measure the performance of Computer Vision models. Objective ground truth images minimise the level of subjective interference in measuring the efficacy of CV edge and corner detectors. Additionally, locating an effective method to contrast detected attributes associated with an image or object, has provided a means to measure the likelihood of an image match between video frames. In combination with existing material and new contributions, this research demonstrates effective object detection and tracking for Augmented Reality systems within a Remote Access Laboratory environment, with no requirement for fiducial markers, or prior knowledge of the environment. The models that have been proposed in the work can be generalised to be used in any cyber-physical environment that facilitates peripherals such as cameras and other sensors

Forum Bauinformatik 2009 : 23. bis 25. September 2009, Universität Karlsruhe (TH)

Tagungsband des 21. Forum Bauinformatik am 23. bis 25. September 2009 an der Universität Karlsruhe (TH). Beiträge von jungen Wissenschaftlern aus den Bereichen Simulationsmodelle, Numerische Methoden, Visualisierung, Informationsvermittlung, Prozess- und Produktmodellierung sowie weiterer informationstechnischer Anwendungen im Bauwesen