3D detection of people

The aim of this work is to obtain the three-dimensional location of people in a scene using the information provided by several cameras; these cameras must have a range of view in common. The place chosen to record the videos for this work is the Nexus Lab in the Universität Stuttgärt. In this work, it is possible to distinguish two main tasks: The first task is to obtain a model of the camera which let us turn the twodimensional information from the images taken from the cameras, in three-dimensional information in a known reference-frame; this topic is studied in chapter 2. The second task is to obtain relevant information from the images of each camera, that is, the location of the people, which appear in an image scene, must be known to compute their three-dimensional location. This information will be obtained by reviewing different types of methods. This topic is described in chapter 3. Finally, the three-dimensional location of the people in the room has been accomplished by integrating the two-dimensional information obtained from the images of each camera with the model of the cameras and knowing their locations in the room. In order to quantify the measurement error of the system, several video tests have been recorded. The error analysis is accomplished in chapter 4.Escuela Técnica Superior de Ingeniería Industria

Motion compensation and very low bit rate video coding

Recently, many activities of the International Telecommunication Union (ITU) and the International Standard Organization (ISO) are leading to define new standards for very low bit-rate video coding, such as H.263 and MPEG-4 after successful applications of the international standards H.261 and MPEG-1/2 for video coding above 64kbps. However, at very low bit-rate the classic block matching based DCT video coding scheme suffers seriously from blocking artifacts which degrade the quality of reconstructed video frames considerably. To solve this problem, a new technique in which motion compensation is based on dense motion field is presented in this dissertation. Four efficient new video coding algorithms based on this new technique for very low bit-rate are proposed. (1) After studying model-based video coding algorithms, we propose an optical flow based video coding algorithm with thresh-olding techniques. A statistic model is established for distribution of intensity difference between two successive frames, and four thresholds are used to control the bit-rate and the quality of reconstructed frames. It outperforms the typical model-based techniques in terms of complexity and quality of reconstructed frames. (2) An efficient algorithm using DCT coded optical flow. It is found that dense motion fields can be modeled as the first order auto-regressive model, and efficiently compressed with DCT technique, hence achieving very low bit-rate and higher visual quality than the H.263/TMN5. (3) A region-based discrete wavelet transform video coding algorithm. This algorithm implements dense motion field and regions are segmented according to their content significance. The DWT is applied to residual images region by region, and bits are adaptively allocated to regions. It improves the visual quality and PSNR of significant regions while maintaining low bit-rate. (4) A segmentation-based video coding algorithm for stereo sequence. A correlation-feedback algorithm with Kalman filter is utilized to improve the accuracy of optical flow fields. Three criteria, which are associated with 3-D information, 2-D connectivity and motion vector fields, respectively, are defined for object segmentation. A chain code is utilized to code the shapes of the segmented objects. it can achieve very high compression ratio up to several thousands

Fehlerkaschierte Bildbasierte Darstellungsverfahren

Creating photo-realistic images has been one of the major goals in computer graphics since its early days. Instead of modeling the complexity of nature with standard modeling tools, image-based approaches aim at exploiting real-world footage directly,as they are photo-realistic by definition. A drawback of these approaches has always been that the composition or combination of different sources is a non-trivial task, often resulting in annoying visible artifacts. In this thesis we focus on different techniques to diminish visible artifacts when combining multiple images in a common image domain. The results are either novel images, when dealing with the composition task of multiple images, or novel video sequences rendered in real-time, when dealing with video footage from multiple cameras.Fotorealismus ist seit jeher eines der großen Ziele in der Computergrafik. Anstatt die Komplexität der Natur mit standardisierten Modellierungswerkzeugen nachzubauen, gehen bildbasierte Ansätze den umgekehrten Weg und verwenden reale Bildaufnahmen zur Modellierung, da diese bereits per Definition fotorealistisch sind. Ein Nachteil dieser Variante ist jedoch, dass die Komposition oder Kombination mehrerer Quellbilder eine nichttriviale Aufgabe darstellt und häufig unangenehm auffallende Artefakte im erzeugten Bild nach sich zieht. In dieser Dissertation werden verschiedene Ansätze verfolgt, um Artefakte zu verhindern oder abzuschwächen, welche durch die Komposition oder Kombination mehrerer Bilder in einer gemeinsamen Bilddomäne entstehen. Im Ergebnis liefern die vorgestellten Verfahren neue Bilder oder neue Ansichten einer Bildsammlung oder Videosequenz, je nachdem, ob die jeweilige Aufgabe die Komposition mehrerer Bilder ist oder die Kombination mehrerer Videos verschiedener Kameras darstellt

Système TAC : Télé-Assistance Collaborative. Réalité augmentée et NTIC au service des opérateurs et des experts dans le cadre d'une tâche de maintenance industrielle supervisée

Le système T.A.C. a été conçu avec l'objectif de proposer un nouveau mode de communication distant. Lorsqu'un opérateur a besoin d'être assisté sur une tâche manuelle, les supports techniques classiques comme le téléphone ou la visioconférence montrent rapidement leurs limites en termes d'interaction humaine. En permettant à un expert distant de voir exactement ce que l'opérateur voit, il peut interagir avec lui en temps réel grâce à la réalité augmentée via un paradigme d'interaction adéquat que nous avons nommé « Picking Outlining Adding ». En guidant l'opérateur grâce à des indices virtuels, l'expert lève les ambiguïtés de langage et les difficultés de communication sont évitées. Les opérations sont ainsi plus facilement exécutées. Les expérimentations que nous avons menées vont dans ce sens, montrant l'efficacité de ce nouveau mode de communication. Qui plus est, les principes d'interactions sont suffisamment généraux pour dépasser le cadre original de la maintenance industrielle.T.A.C. system was built in order to propose a new mode of remote communication. When an operator needs to be assisted on a manual task, classical technical support methods as phone or visioconference rapidly show their limits in terms of human interaction. By allowing a distant expert to see exactly what an operator is seeing, he could interact with him in interactive time thanks to augmented reality via an adequate interaction paradigm we named « Picking Outlining Adding ». In guiding the operator through visual guidance information, expert removes the ambiguities of language and communications difficulties are avoided. Operations are then easily performed. The experiments we have conducted go in this direction, showing the effectiveness of this new mode of communication. Moreover, interactions principles are sufficiently general to be applied to other use cases that go beyond the originally planned industrial maintenance