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Creating content for games costs a lot of time and money. This thesis will use the Lindenmayer system for procedural content creation inside the game to answer the question, how can L-systems be exploited for gameplay mechanic purposes? The application implemented in Unity 3D is a form of tree L-system with player controlled recursion, independent branches and poisonous branches. The recursion can allow the player to grow strategically, independent branches can be used as seed and grow on its own if they break o , poisonous branches to force players to think when navigating.

Les chenaux sont des structures sédimentaires clefs dans le transport et le dépôt de sédiments depuis les continents jusqu'aux planchers océaniques. Leurs dépôts perméables permettent la circulation et le stockage de fluides. Comme illustré avec les systèmes turbiditiques, le remplissage de ces chenaux est très hétérogène. Son impact sur la connectivité des dépôts perméables est amplifié par les variations d'organisation spatiale des chenaux. Mais du fait de l'aspect lacunaire des données, l'architecture de ces structures souterraines n'est que partiellement connue. Dans ce cas, les simulations stochastiques permettent d'estimer les ressources et les incertitudes associées. De nombreuses méthodes ont été développées pour reproduire ces environnements. Elles soulèvent deux questions capitales : comment analyser et comparer la connectivité de simulations stochastiques ? Comment améliorer la représentation de la connectivité dans les simulations stochastiques de chenaux et réduire les incertitudes ? La première question nous a conduits à développer une méthode pour comparer objectivement des réalisations en se concentrant sur la connectivité. L'approche proposée s'appuie sur les composantes connexes des simulations, sur lesquelles sont calculés plusieurs indicateurs. Une représentation par positionnement multidimensionnel (MDS) facilite la comparaison des réalisations. Les observations faites grâce au MDS sont ensuite validées par une carte de chaleur et les indicateurs. L'application à un cas synthétique de complexes chenaux/levées montre les différences de connectivité entre des méthodes et des valeurs de paramètres différentes. En particulier, certaines méthodes sont loin de reproduire des objets avec une forme de chenaux. La seconde question amène deux principaux problèmes. Premièrement, il apparaît difficile de conditionner des objets très allongés, comme des chenaux, à des données de puits ou dérivées de données sismiques. Nous nous appuyons sur une grammaire formelle, le système de Lindenmayer, pour simuler stochastiquement des objets chenaux conditionnés. Des règles de croissance prédéfinies contrôlent la morphologie du chenal, de rectiligne à sinueuse. Cette morphologie conditionne les données au fur et à mesure de son développement grâce à des contraintes attractives ou répulsives. Ces contraintes assurent le conditionnement tout en préservant au mieux la morphologie. Deuxièmement, l'organisation spatiale des chenaux apparaît peu contrôlable. Nous proposons de traiter ce problème en intégrant les processus qui déterminent l'organisation des chenaux. Un premier chenal est simulé avec un système de Lindenmayer. Puis ce chenal migre à l'aide d'une simulation gaussienne séquentielle ou d'une simulation multipoints. Cette approche reproduit les relations complexes entre des chenaux successifs sans s'appuyer sur des modèles physiques partiellement validés et au paramétrage souvent contraignant. L'application de ces travaux à des cas synthétiques démontre le potentiel de ces approches. Elles ouvrent des perspectives intéressantes pour mieux prendre en compte la connectivité dans les simulations stochastiques de chenaux / Channels are the main sedimentary structures for sediment transportation and deposition from the continents to the ocean floor. The significant permeability of their deposits enables fluid circulation and storage. As illustrated with turbiditic systems, those channel fill is highly heterogeneous. Combined with the spatial organization of the channels, this impacts significantly the connectivity between the permeable deposits. The scarcity of the field data involves an incomplete knowledge of these subsurface reservoir architectures. In such environments, stochastic simulations are used to estimate the resources and give an insight on the associated uncertainties. Several methods have been developed to reproduce these complex environments. They raise two main concerns: how to analyze and compare the connectivity of a set of stochastic simulations? How to improve the representation of the connectivity within stochastic simulations of channels and reduce the uncertainties? The first concern leads to the development of a method to objectively compare realiza-tions in terms of connectivity. The proposed approach relies on the connected compo-nents of the simulations, on which several indicators are computed. A muldimensional scaling (MDS) representation facilitates the realization comparison. The observations on the MDS are then validated by the analysis of the heatmap and the indicators. The appli-cation to a synthetic case study highlights the difference of connectivity between several methods and parameter values to model channel/levee complexes. In particular, some methods are far from representing channel-shaped bodies. Two main issues derive from the second concern. The first issue is the difficulty to simulate a highly elongated object, here a channel, conditioned to well or seismic-derived data. We rely on a formal grammar, the Lindenmayer system, to stochastically simulate conditional channel objects. Predefined growth rules control the channel morphology to simulate straight to sinuous channels. That morphology conditions the data during its development thanks to attractive and repulsive constraints. Such constraints ensure the conditioning while preserving at best the channel morphology. The second issue arises from the limited control on the channel organization. This aspect is addressed by taking into account the evolution processes underlying channel organization. An initial channel is simulated with a Lindenmayer system. Then that channel migrates using sequential Gaussian simulation or multiple-point simulation. This process reproduces the complex relationships between successive channels without relying on partially validated physical models with an often constraining parameterization. The applications of those various works to synthetic cases highlight the potentiality of the approaches. They open up interesting prospects to better take into account the connectivity when stochastically simulating channels

Lindenmayer (L) systems form a class of interesting computational formalisms due to their parallel nature, the various circumstances under which they operate, the restrictions imposed on language acceptance, and other attributes. These systems have been extensively studied in the Formal Languages literature. In the past decade a new type of Lindenmayer system had been proposed: Watson-Crick Lindenmayer Systems. These systems are essentially a marriage between Developmental systems and DNA Computing. At their heart they are Lindenmayer systems augmented with a complementary relation amongst elements in the system just as the base pairs of DNA strands can be complementary with respect to one another. When conditions and a mechanism for 'switching' the state of a computation to it's complementary version are provided then these systems can become surprisingly more powerful than the L systems which form their backbone. This dissertation explores the computational power of new variants of Watson-Crick L systems. It is found that many of these systems are Computationally-Complete. These investigations differ from prior ones in that the systems under consideration have extended alphabets and usually Regular Triggers for complementation are considered as opposed to Context-Free Triggers investigated in previous works. / Thesis (Master, Computing) -- Queen's University, 2010-12-06 18:29:23.584

The potential of L-systems is explored byprocedurally generating patterns for use as video game content.By procedurally generating content for video games, thedevelopment costs of game development can be significantlyreduced. An artifact in the form of a tower defense game isdeveloped and tested to evaluate the generation algorithm. Thealgorithm was successful in generating a wide range of pattern anduser feedback indicates a high level of perceived variation. Thealgorithm is highly customizable and could have applications invarious game content such as particle systems or weapons

As imagens de angiografia por ressonância magnética (angio-RM) ou por tomografia computadorizada (angio-TC) permitem uma análise minuciosa das redes vasculares. A segmentação de redes vasculares a partir de tais imagens é uma das tarefas iniciais no diagnóstico de doenças vasculares como estenoses ou aneurismas. Porém, a grande diversidade de arquiteturas dos vasos dificulta a validação dos algoritmos de segmentação. Assim, a construção de redes vasculares sintéticas realistas permitem validar novas metodologias de segmentação de vasos. Este trabalho descreve uma metodologia de geração de redes vasculares sintéticas em três dimensões utilizando sistemas de Lindenmayer (L-systems) estocásticos. Para atingir esse objetivo, foram implementados um analisador léxico, um analisador sintático e um gerador de L-systems para a criação de vasos sintéticos baseado em gramáticas. A parametrização destas gramáticas possibilita a simulação de características naturais de vasos reais como o ângulo de bifurcação, comprimento, diâmetro médio e possibilita a simulação de anomalias vasculares. As expressões resultantes são utilizadas para criar imagens angiográficas sintéticas que simulam a distribuição de intensidades dos vasos em imagens angio-RM e angio-TC reais. As redes vasculares sintéticas podem também ser delimitadas por superfícies 3D arbitrárias de forma similar à geometria de órgãos. A flexibilidade de parametrização e natureza estocástica desta metodologia faz com que ela se torne uma ferramenta ideal para a validação de algoritmos de segmentação de vasos em imagens angiográficas. / Magnetic resonance angiography (MRA) or computed tomography angiography (CTA) images allow for a thorough analysis of the blood vessels. Vessel segmentation from MRA or CTA is thus the primary task in the diagnosis of vascular diseases such as stenosis and aneurysms. The wide architectural variability of the blood vessels, however, hinders the validation of vascular segmentation methods. The construction of synthetic realistic vascular architecture trees will aid in the validation of new vessel segmentation methodologies. This thesis describes a three-dimensional synthetic blood vessel generation methodology that employs stochastic Lindenmayer systems (L-systems). For this purpose, we implemented a parser and a generator of L-systems to create grammars that represent blood vessel architectures. The parameterization of the grammar allows one to simulate natural features of real vessels such as bifurcation angle, average length and diameter, and also accounts for vascular anomalies. The resulting expressions are used to create synthetic angiographic images that mimic real vessel intensity distributions in MRA and CTA. Blood vessel growth can also be delimited by arbitrary 3D surfaces that may represent organ geometries. The flexibility in the parameterization and stochastic nature of this methodology makes it an ideal tool for the validation of blood vessel segmentation algorithms from angiographic images.

As imagens de angiografia por ressonância magnética (angio-RM) ou por tomografia computadorizada (angio-TC) permitem uma análise minuciosa das redes vasculares. A segmentação de redes vasculares a partir de tais imagens é uma das tarefas iniciais no diagnóstico de doenças vasculares como estenoses ou aneurismas. Porém, a grande diversidade de arquiteturas dos vasos dificulta a validação dos algoritmos de segmentação. Assim, a construção de redes vasculares sintéticas realistas permitem validar novas metodologias de segmentação de vasos. Este trabalho descreve uma metodologia de geração de redes vasculares sintéticas em três dimensões utilizando sistemas de Lindenmayer (L-systems) estocásticos. Para atingir esse objetivo, foram implementados um analisador léxico, um analisador sintático e um gerador de L-systems para a criação de vasos sintéticos baseado em gramáticas. A parametrização destas gramáticas possibilita a simulação de características naturais de vasos reais como o ângulo de bifurcação, comprimento, diâmetro médio e possibilita a simulação de anomalias vasculares. As expressões resultantes são utilizadas para criar imagens angiográficas sintéticas que simulam a distribuição de intensidades dos vasos em imagens angio-RM e angio-TC reais. As redes vasculares sintéticas podem também ser delimitadas por superfícies 3D arbitrárias de forma similar à geometria de órgãos. A flexibilidade de parametrização e natureza estocástica desta metodologia faz com que ela se torne uma ferramenta ideal para a validação de algoritmos de segmentação de vasos em imagens angiográficas. / Magnetic resonance angiography (MRA) or computed tomography angiography (CTA) images allow for a thorough analysis of the blood vessels. Vessel segmentation from MRA or CTA is thus the primary task in the diagnosis of vascular diseases such as stenosis and aneurysms. The wide architectural variability of the blood vessels, however, hinders the validation of vascular segmentation methods. The construction of synthetic realistic vascular architecture trees will aid in the validation of new vessel segmentation methodologies. This thesis describes a three-dimensional synthetic blood vessel generation methodology that employs stochastic Lindenmayer systems (L-systems). For this purpose, we implemented a parser and a generator of L-systems to create grammars that represent blood vessel architectures. The parameterization of the grammar allows one to simulate natural features of real vessels such as bifurcation angle, average length and diameter, and also accounts for vascular anomalies. The resulting expressions are used to create synthetic angiographic images that mimic real vessel intensity distributions in MRA and CTA. Blood vessel growth can also be delimited by arbitrary 3D surfaces that may represent organ geometries. The flexibility in the parameterization and stochastic nature of this methodology makes it an ideal tool for the validation of blood vessel segmentation algorithms from angiographic images.