Modeling dendritic shapes - using path planning

Dendritic shapes are commonplace in the natural world such as trees, lichens, coral and lightning. Models of dendritic shapes are widely needed in many areas. Because of their branching fractal and erratic structures modeling dendritic shapes is a tricky task. Existing methods for modeling dendritic shapes are slow and complicated.In this thesis we present a procedural algorithm of using path planning to model dendritic shapes. We generate a dendrite by finding the least-cost paths from multiple endpoints to a common generator and use the dendrite to build the geometric model. With the control handles of endpoint placement, fractal shape, edge weights distribution and path width, we create different shapes of dendrites that simulate different kinds of dendritic shapes very well. Compared with some existing methods, our algorithm is fast and simple

Pore network modelling of fingering phenomena during unsteady-state waterflooding of heavy oils

Although thermal methods have been popular and successfully applied in heavy oil recovery, they are often found to be uneconomic or impractical. Therefore, alternative production protocols are being actively pursued and interesting options are water and polymer flooding. Such techniques have been successfully tested in recent laboratory investigations, where oil recovery was found to be much higher than expected. Moreover, in some of the core scale waterflood experiments reported using 2D slabs of Bentheimer sandstone, X-ray scans performed during the flooding sequence provided evidence of an interesting new phenomenon – post breakthrough, highly dendritic water fingers were seen to thicken and coalesce, forming braided water channels and improving sweep efficiency. However, despite encouraging results, these experimental studies show that the mechanisms governing water displacing extra heavy oil are still poorly understood. This means that the optimization of this process for eventual field applications is still somewhat problematic. Ideally, a combination of two-phase flow experiments and simulations should be put in place to help inform our understanding of the process. To this end, a new fully dynamic network model is described. It has been developed to investigate unsteady state drainage floods and has been applied here in the context of waterfloods of heavy oil in oil-wet media. It has subsequently been used to investigate finger thickening during water flooding of extra-heavy oils. The displacement physics has been implemented at the pore scale and, following a successful benchmarking exercise against numerous micromodel experiments, a range of slab-scale (30cm x 30cm) simulations has been carried out and compared with the corresponding experimental observations. They reveal that the model is able to replicate finger architectures similar to those observed in the experiments. Subsequently, for the first time to our knowledge, finger thickening following water breakthrough is reproduced and interpreted. The simulator is then used to investigate the effects of different system parameters on finger swelling behaviour. Finally, a sensitivity study is performed to better understand the effects of different system variables upon the sweep efficiency, the displacement front stability and unsteady-state relative permeability

Wizualizacja zjawisk topnienia i sublimacji

Niniejsza monografia dotyczy wizualizacji zjawisk topnienia i sublimacji, które są przejściem fazowym z ciała stałego odpowiednio do cieczy i gazu. Modelem granicy miedzy dwoma fazami jest powierzchnia międzyfazowa, dlatego topnienie i sublimacja mogą być rozpatrywane jako przesuwanie powierzchni międzyfazowej z towarzysząca mu wymiana ciepła. Wizualizacja omawianych zjawisk wymaga omówienia różnych jej aspektów – od sposobu reprezentacji danych graficznych, przez algorytmy przetwarzania tych danych i ich optymalizacje, problemy renderingu czasu rzeczywistego, po metody weryfikacji jej wyników. Wymienione kwestie zostały zebrane w niniejszej ksiażce

Reconstruction and rendering of time-varying natural phenomena

While computer performance increases and computer generated images get ever more realistic, the need for modeling computer graphics content is becoming stronger. To achieve photo-realism detailed scenes have to be modeled often with a significant amount of manual labour. Interdisciplinary research combining the fields of Computer Graphics, Computer Vision and Scientific Computing has led to the development of (semi-)automatic modeling tools freeing the user of labour-intensive modeling tasks. The modeling of animated content is especially challenging. Realistic motion is necessary to convince the audience of computer games, movies with mixed reality content and augmented reality applications. The goal of this thesis is to investigate automated modeling techniques for time-varying natural phenomena. The results of the presented methods are animated, three-dimensional computer models of fire, smoke and fluid flows.Durch die steigende Rechenkapazität moderner Computer besteht die Möglichkeit immer realistischere Bilder virtuell zu erzeugen. Dadurch entsteht ein größerer Bedarf an Modellierungsarbeit um die nötigen Objekte virtuell zu beschreiben. Um photorealistische Bilder erzeugen zu können müssen sehr detaillierte Szenen, oft in mühsamer Handarbeit, modelliert werden. Ein interdisziplinärer Forschungszweig, der Computergrafik, Bildverarbeitung und Wissenschaftliches Rechnen verbindet, hat in den letzten Jahren die Entwicklung von (semi-)automatischen Methoden zur Modellierung von Computergrafikinhalten vorangetrieben. Die Modellierung dynamischer Inhalte ist dabei eine besonders anspruchsvolle Aufgabe, da realistische Bewegungsabläufe sehr wichtig für eine überzeugende Darstellung von Computergrafikinhalten in Filmen, Computerspielen oder Augmented-Reality Anwendungen sind. Das Ziel dieser Arbeit ist es automatische Modellierungsmethoden für dynamische Naturerscheinungen wie Wasserfluss, Feuer, Rauch und die Bewegung erhitzter Luft zu entwickeln. Das Resultat der entwickelten Methoden sind dabei dynamische, dreidimensionale Computergrafikmodelle

MaxControl: ein objektorientiertes Werkzeug zur automatischen Erstellung von 3D-Computeranimationsfilmen und dessen Integration in eine professionelle 3D-Animationssoftware

Durch die wachsende Computerleistung können 3D-Computeranimationen sehr komplexe Szenen mit ebenso komplexen zeitlichen Abläufen animiert darstellen. Jedoch ist neben der Erstellung einer komplexen Szene auch deren Animation entsprechend aufwendig, wenn keine Automatisierungen genutzt werden können. Das in dieser Arbeit entwickelte Werkzeug MaxControl ist ein System zur automatischen Animation von nicht-interaktiven 3D-Animationsfilmen. Dies wird durch die Simulation von Verhaltensweisen erreicht, die den 3D-Objekten zugewiesen werden