This thesis describes the development of a distributed occlusion culling solution for complex generic scenes. Moving these calculations onto a second computer should decrease the load on the actual rendering system and therefore allow higher framerates. This work includes an introduction to parallel rendering systems and discussion of suitable culling algorithms. Based on these parts, a client-server system for occlusion culling is developed. The test results of a prototypical implementation form the last part of this thesis.

Collision detection between deforming models is a difficult problem for collision detection systems to handle. This problem is even more difficult when deformations are unconstrained, objects are in close proximity to one another, and when the entity count is high. We propose a method to perform collision detection between multiple deforming objects with unconstrained deformations that will give good results in close proximities. Currently no systems exist that achieve good performance on both unconstrained triangle level deformations and deformations that preserve edge connectivity. We propose a new system built as a combination of Graphics Processing Unit (GPU) based culling and Axis Aligned Bounding Box (AABB) based culling. Techniques for performing hierarchy-less GPU-based culling are given. We then discuss how and when to switch between GPU-based culling and AABB based techniques.

Visual effects for film and animation often require simulated granular materials, such as sand, wheat, or dirt, to meet a director's needs. Simulating granular materials can be time consuming, in both computation and labor, as these particulate materials have complex behavior and an enormous amount of small-scale detail. Furthermore, a single cubic meter of granular material, where each grain is a cubic millimeter, would contain a billion granules, and simulating all such interacting granules would take an impractical amount of time for productions. This calls for a simplified model for granular materials that retains high surface detail and granular behavior yet requires significantly less computational time. Our proposed method simulates a minimal number of individual granules while retaining particulate detail on the surface by supporting surface particles with simplified interior granular models. We introduce a multi-state model where, depending on the material state of the interior granules, we replace interior granules with a simplified simulation model for the state they are in and automate the transitions between those states. The majority of simulation time can thus be focused on visible portions of the material, reducing the time spent on non-visible portions, while maintaining the appearance and behavior of the mass as a whole.

Il existe plusieurs moyens d'augmenter la rentabilité d'une exploitation laitière. Parmi celles-ci, la réforme peut avoir un effet sur la production moyenne du troupeau et par conséquent sur les coûts de production de par la modulation de la structure du troupeau qu'elle entraîne. Afin de déterminer une rentabilité optimale des troupeaux, il est donc important de quantifier la réforme et de comprendre les mécanismes qui amènent à réformer un animal. Cette thèse a pour objectif principal de décrire la réforme dans les troupeaux laitiers du Québec. Plus précisément, elle vise à quantifier le taux de réforme, à explorer la relation entre le troupeau, le taux de réforme et le risque individuel de réforme, à déterminer l'effet causal de la mammite clinique sur la réforme, et à identifier les critères de décision utilisés lors de la réforme par les producteurs et les différents intervenants à la ferme. Une étude rétrospective longitudinale a été menée à partir des informations de santé et de production des vaches des troupeaux laitiers du Québec (Canada). Dix années de données, entre 2001 et 2010, ont été utilisées afin de déterminer des profils de troupeau et leurs taux de réforme, et un éventuel lien entre ceux-ci. L'influence du troupeau sur le risque individuel de réforme d'une part, et l'effet causal de la mammite clinique sur la réforme d'autre part, ont été explorés respectivement par analyse contextuelle et à l'aide d'un modèle marginal structural. Les critères de décision de réforme communs entre les producteurs, vétérinaires et autres conseillers ont été identifiés grâce à la méthodologie Q, qui permet de révéler la structure décisionnelle des individus. Cette étude a permis de quantifier un taux de réforme moyen de 32% sur les dix années de suivi de la cohorte, avec des variations importantes entre troupeaux. Il n'a pas été possible de déterminer des profils spécifiques de troupeaux en fonction d'un ensemble de caractéristiques liées à leurs performances de reproduction, de production, à leur gestion et indicateurs de santé. Il est, par contre, possible de les distinguer en fonction de certaines caractéristiques prise une à une et d'y associer le taux de réforme, notamment pour la gestion, la reproduction et la quantité de lait produite. Ces caractéristiques peuvent servir de variables contextuelles dans des analyses multiniveaux. Un effet contextuel du troupeau est présent dans le risque individuel de réforme, mais limité. Il résulte essentiellement de la pression exercée par les primipares arrivant dans le troupeau. Le risque de réforme dû à la mammite clinique, évalué dans le cadre contrefactuel d'une étude longitudinale où l'exposition est dépendante du temps, est comparable entre primipares et multipares. Pour ce risque, la production laitière a moins d'influence chez les primipares que chez les multipares. Les producteurs et leurs conseillers se réfère à un cadre de décision commun pour réformer une vache, se référant essentiellement à la santé mammaire de la vache et à sa production de lait. Le taux de réforme du troupeau n'intervient pas dans la décision de réformer une vache particulière. / There are several ways to increase the profitability of dairy farms. Among them, culling can affect the average herd production and therefore the costs of production, by modifying the herd structure. In order to determine an optimal herd profitability, it is important to quantify the culling rates and to understand the mechanisms leading to the culling of an animal. The main objective of this thesis is to describe culling in Québec dairy herds. Specifically, it aims to quantify the culling rates, to explore relationship between the herd, the culling rate, and the individual culling risk, to determine the causal effect of clinical mastitis on culling, and to identify the decision-making criteria used by producers and farm advisers. A retrospective longitudinal study was conducted on health and production data from cows in dairy herds from Québec, Canada. Ten years of data, between 2001 and 2010, were used to determine herd profiles and their culling rates, and their potential relationship. Herd influence on individual culling risk and the causal effect of clinical mastitis were explored respectively by contextual analysis and by using a marginal structural model. Shared criteria on culling decisions held by dairy producers, veterinarians and other advisers were identified with the help of the Q-methodology, which provides a means to reveal the decision structure of individuals. This study quantified an average culling rate of 32% based on ten years of follow-up, with significant variations between herds. Specific herd profiles according to a set of characteristics related to their reproductive and production performances, management and health indicators could not be determined. It is however possible to distinguish herds against certain unique feature taken one by one and to relate it to the culling rate, including herd management, reproduction performances, and milk production. These indicators can be considered as contextual variables in multilevel analyses. A herd contextual effect is present in the cow culling risk, but limited. It is mainly due to the pressure of heifers coming into the herd. Culling risk due to clinical mastitis, considered in the counterfactual framework of a longitudinal study where exposure is time-varying, is comparable between primiparous and multiparous cows. For this risk, dairy production has less influence in primiparous that in multiparous cows. Producers and their advisers share a common framework for culling decision-making, referring essentially to cow's udder health and her milk production. Herd culling rate is not involved in the decision to cull a specific cow.

Demonstration videos can be found on fr.linkedin.com/in/doriangomez/ / Cette thèse porte sur la modélisation procédurale de mondes virtuels étendus dans le domaine de l’informatique graphique. Nous proposons d’exploiter les propriétés de visibilité entre régions élémentaires de la scène, que nous appelons tuiles, pour contrôler sa construction par pavage rectangulaire. Deux objectifs distincts sont visés par nos travaux : (1) fournir aux infographistes un moyen efficace pour générer du contenu 3D pour ces scènes virtuelles de très grande taille, et (2) garantir, dès la création du monde, des performances de rendu et de visualisation efficace. Pour cela, nous proposons plusieurs méthodes de détermination de la visibilité en 2D et en 3D. Ces méthodes permettent l’évaluation d’ensembles potentiellement visibles (PVS) en temps interactif ou en temps réel. Elles sont basées sur les calculs de lignes séparatrices et de lignes de support des objets, mais aussi sur l’organisation hiérarchique des objets associés aux tuiles. La première technique (2D) garantit l’occultation complète du champ visuel à partir d’une distance fixe, spécifiée par le concepteur de la scène, depuis n’importe quel endroit sur le pavage. La seconde permet d’estimer et de localiser les tuiles où se propage la visibilité, et de construire le monde en conséquence. Afin de pouvoir générer des mondes variés, nous présentons ensuite l’extension de cette dernière méthode à la 3D. Enfin, nous proposons deux méthodes d’optimisation du placement des objets sur les tuiles permettant d’améliorer leurs propriétés d’occultation et leurs impacts sur les performances de rendu tout en conservant l’atmosphère créée par l’infographiste par ses choix de placement initiaux. / This thesis deals with procedural modeling applied to extended worlds for computer graphics.We study visibility applied to tiling patterns, aiming at two distinct objectives : (1) providing artists with efficient tools to generate 3D content for very extended virtual scenes, and (2) guaranteeing that this content improves performance of subsequent renderings, during its construction. We propose several methods for 2D and 3D visibility determination, in order to achieve interactive or real-time evaluation of potentially visible sets (PVS). They are based on the concepts of separating and supporting lines/planes, as well as objects hierarchies over tiles. Our first 2D method guarantees full occlusion of the visual field (view frustum) beyond a fixed distance, regardless of the observer’s location on a tiling. The second method enables fast estimation and localization of visible tiles, and builds up a virtual world accordingly. We also extend this method to 3D. Finally, we present two methods to optimize objects locations on tiles, and show how to improve rendering performance for scenes generated on the fly.

Infectious diseases are increasingly being recognised as significant threatening processes in conservation biology. Developing strategies to effectively manage infectious diseases in wildlife is, therefore, of the utmost importance to the maintenance of global biodiversity. The effective management of infectious diseases relies on understanding the ecology of the host, the epidemiological characteristics of the pathogen and the impacts of the pathogen on the host population. However, for most wildlife-disease systems this information remains poorly understood. This is particularly true for endangered species threatened by novel infectious agents as opportunities to observe and assess disease impacts and host-pathogen dynamics in the wild are limited. The Tasmanian devil (Sarcophilus harrisii), the world’s largest carnivorous marsupial, is threatened with extinction as a result of an epidemic of an emerging disease, a fatal infectious cancer known as Devil Facial Tumour Disease (DFTD). In this thesis I capitalised on a unique dataset from a population of Tasmanian devils where disease arrived part-way through an intensive longitudinal study, and utilised existing genetic samples collected prior to DFTD outbreak, to determine the impact of DFTD on the demography, population dynamics, genetic diversity and population genetic structure of wild Tasmanian devils. I then used this knowledge of the impacts of DFTD impacts in an unmanaged population to evaluate the effectiveness of a disease management trial involving the selective culling of infected individuals. I employed mark-recapture models to investigate the impact of DFTD on age-specific and sex-specific apparent survival rates, to examine the pattern of variation in infection rates (force of infection), and to investigate the impact of DFTD on population growth rate. I investigated demography, life-history traits and morphometric parameters of infected and uninfected individuals to determine the impacts of DFTD on age-structure and sex-structure, female fecundity and individual growth rates. I used this information to assess the population’s ability to respond to low population densities and to compensate for the detrimental impacts of DFTD. To determine the genetic consequences of disease-induced population decline I used microsatellite DNA to compare genetic diversity, population genetic structure and dispersal patterns in three Tasmanian devil populations prior to and following DFTD outbreaks. Capture-mark-recapture analyses revealed that the arrival of DFTD triggered an immediate decline in apparent survival rates of devils, the rate of which was predicted well by the increase in disease prevalence in the population over time. Transition rates of healthy individuals to the diseased class (the force of infection) increased in relation to disease prevalence, while the arrival of DFTD coincided with a marked and ongoing decline in the population growth rate. There was a significant change to the age structure following the arrival of DFTD. This shift to a younger population was caused by the loss of older individuals as a direct consequence of DFTD-driven declines in adult survival rates. Evidence of reproductive compensation in response to these disease impacts was observed via a reduction in the age of sexual maturity of females over time. However, widespread precocial breeding in devils was precluded by physiological and ecological constraints that limited the ability of one year olds to breed. Using temporally-replicated spatial genetic data, I found evidence of increased inbreeding following DFTD arrival and greater population genetic differentiation in post-disease populations. These changes appeared to be driven by a combination of selection and altered dispersal patterns of females in DFTD-affected populations. Comparison of demographic and epidemiological parameters indicative of disease progression and impact between the managed and unmanaged populations revealed that selective culling of infected individuals neither slowed the rate of disease progression nor reduced the population level impacts of this debilitating disease; with culling mortality simply compensating for disease mortality. This thesis provides one of the few direct empirical evaluations of the impact of an emerging wildlife disease epidemic on a wild population. This thesis revealed that infectious diseases can result in major demographic and genetic changes in host populations over relatively few generations and short time-scales. Results showing dramatic and ongoing population declines and very limited population compensation in DFTD-affected populations indicate that DFTD poses a significant extinction risk for wild devil populations. Hence, this study confirms that host-specific pathogens can pose a significant extinction risk for wild species, even in the absence of alternate reservoir hosts, a finding critical to our understanding of host-pathogen dynamics. My thesis also highlights the potential negative interplay between disease susceptibility and host genetic variability, which is of utmost importance to the management of novel wildlife epizootics and the conservation of threatened wildlife in general. The thorough understanding of the ecology and impacts of DFTD in the wild obtained in this study has provided a solid base from which to both rigorously assess the outcome of management strategies and also formulate recommendations for the management of this disease in the wild. The lack of evidence for successful control of the DFTD epidemic in a wild population during the first phase of a selective culling experimental adaptive management approach, points to the need to implement a multi-faceted disease management program when attempting to control a novel infectious disease in the wild. By drawing on the lessons learnt in this case study I show that it is possible to establish a set of general guidelines for the future management of infectious diseases in threatened wildlife.

The target of this diploma work was to find and apply the most effective simulation model of pig breeding at particular company. Partial goal of this work was to identify the breeding technologies and simulation methods. The data was elaborated in program Microsoft Office Excel 2010 and the simulation model was compiled in @RISK 5.5 software. After the application of simulation model I found out, that in the chosen company was landrase pig race getting higher profitability than bílé ušlechtilé pig race. Another result points to that the shorter time of weaning of piglets has positive influence at company profitability. On the base of this results was recommended to the company to rise up the part of landrase pig race and to short the time of weaning of piglets. There was also generated the curved line of sow´s profitability in it´s individual litters, which helps to culling of sows and to integration of sows into the herd.

Made available in DSpace on 2014-08-20T14:38:04Z (GMT). No. of bitstreams: 1 dissertacao_rafael_ulguim.pdf: 242678 bytes, checksum: 818cdda987f14895f73f146504604940 (MD5) Previous issue date: 2011-03-25 / In conventional swine production systems, with acquisition of replacement gilts either from commercial suppliers or internal replacement, high culling rates are associated with reduced productive efficiency. The culling pattern of alternative replacement systems, consisting of four-site units (4S) that prepare replacement gilts to be sold pregnant to piglet-production units (PP) are not yet characterized. The objectives of this study are: to characterize the culling pattern and the associations between the culling reasons and female reproductive efficiency in 4S and PP units; and to associate culling reasons recorded at farm level with examining genital organs of culled females at a slaughterhouse. Individual female records of culled females (n = 5,013) were extracted from databases of three 4S units and ten PP units. A frequency distribution was generated for the culling reasons, which were classified as: reproductive failure, low productivity, age, locomotor problems; and other causes. The evaluated parameters of reproductive efficiency were: herd lifetime; non productive days (NPD); and total number of piglets born during herd lifetime (PBL), per parity (PBP) and per year of herd lifetime (PBY). Such parameters were compared according to the production units, parity at culling (PC) and culling reason. At the slaughterhouse, the uterus and the ovaries of 311 culled females from the same 13 units were evaluated. Culling for locomotor problems was more frequent in 4S units, whereas culling for low productivity was more frequent in PP units. In 4S units, herd lifetime was 71.8 ± 0.8 d and the first service to culling interval was 57.1 ± 0.8 d. In the PP units, herd lifetime was 672.5 ± 7.1 d and PC was 4.4 ± 0.1. Parameters related to piglets production over time were similar to those observed in conventional production systems, with the lowest PBL (33.5 ± 1.1) observed for females culled for reproductive failure and PBY (22.8 ± 0.3) for those culled for productivity. At the slaughterhouse evaluation, the frequency of ovaries presenting cysts and no structures were 12.6% and 10.9%, respectively. No association was observed among such pathologies and the reproductive failures recorded as the reasons for female culling (P > 0.05). The production system combining 4S and PP units presented PC somewhat increased and decreased NPD, in comparison with conventional replacement systems, indicating a potential for increasing female retention rates and reducing the impact of premature female culling on herd reproductive efficiency. / Em sistemas convencionais de produção de suínos, com aquisição de fêmeas de reposição de fornecedores externos ou com reposição interna, a alta taxa de descarte de fêmeas é associada com menor eficiência produtiva. Sistemas alternativos de reposição, com unidades de Quarto Sítio (4S) para a preparação de leitoas de reposição que são vendidas gestantes para unidades de produção de leitões (UPL), não possuem o padrão de descarte caracterizado. Os objetivos deste trabalho foram: caracterizar os descartes em 4S e UPL e a relação das causas de descarte com indicadores de eficiência reprodutiva; e associar as causas de descarte atribuídas na granja às falhas reprodutivas com o exame de órgãos genitais das fêmeas descartadas, no frigorífico. Registros individuais de 5.013 fêmeas descartadas foram extraídos do banco de dados de três unidades de 4S e dez UPL. Distribuições de frequencia foram geradas para as razões de descarte, que foram divididas em: falhas reprodutivas; produtividade; idade; problemas locomotores; e causas diversas. Os indicadores de eficiência reprodutiva avaliados incluíram: tempo de permanência no plantel; dias não produtivos (DNP); e total de leitões nascidos durante a vida reprodutiva (TN), por parto (MN) e por ano (NPA). Estes indicadores foram comparados em função da unidade de produção, da ordem de parto ao descarte (OP) e da razão atribuída para o descarte. No frigorífico, foram avaliados os ovários e o útero de 311 fêmeas descartadas das 13 granjas selecionadas. Os descartes por problemas locomotores foram os mais frequentes nas unidades de 4S, enquanto que os descartes por baixa produtividade foram os mais frequentes nas UPL. Nas unidades de 4S, o tempo médio de permanência foi de 71,8 ± 0,8 d e intervalo primeiro serviço-descarte de 57,1 ± 0,8 d. Nas UPL, o tempo de permanência foi de 672,5 ± 7,1 d e a OP média foi de 4,4 ± 0,1. Os indicadores de produtividade relacionados a produção de leitões, mostraram padrão semelhante ao verificado em sistemas convencionais, onde o TN foi menor para os descartes por falha reprodutiva (33,5 ± 1,1), assim como o NPA nos descartes por produtividade (22,8 ± 0,3) foi inferior as demais razões de descarte. No frigorífico, a frequência de ovários lisos foi de 10,9% e a de cistos ovarianos de 12,6%. Não houve associação entre as patologias observadas e a causa atribuída para o descarte por falhas reprodutivas. O sistema de produção que combina unidades de 4S e UPL apresentou uma OP média ao descarte relativamente elevada e uma redução no acúmulo de DNP, o que indica a possibilidade de maior taxa de retenção de fêmeas e redução do impacto produtivo do descarte precoce de fêmeas sobre a eficiência reprodutiva.

Diese Arbeit beschreibt den Entwurf und die Funktionsweise einer parallelen OpenGL-Renderingschnittstelle, die den effizienten Betrieb unmodifizierter graphischer Anwendungen auf segmentierten Anzeigen ermöglicht. Diese Schnittstelle integriert sich vollständig in eine verteilte graphische Benutzeroberfläche. Die herausragende Eigenschaft der entwickelten parallelen OpenGL-Schnittstelle ist ihre gleich bleibende Bildrate bei wachsender Anzahl von Segmenten. Als Erweiterung des frei verfügbaren Chromium-Systems stellt die Implementation eine virtuelle Graphikpipeline mit der Gesamtauflösung der segmentierten Anzeige bereit, die den eingehenden Datenstrom über ein Kommunikationsnetzwerk an die Knoten eines Visualisierungsclusters überträgt. Jeder Knoten des Clusters rendert einen Ausschnitt des Gesamtbildes und bringt diesen auf dem zugehörigen Segment synchronisiert zur Anzeige. Die interne Verarbeitung der von der Applikation generierten OpenGL-Datenströme unterscheidet sich jedoch grundlegend von der existierenden Lösung. Während die Tilesort-SPU von Chromium die Daten entsprechend der Segmentierung der Anzeige sortiert und sequenziell an die relevanten Knoten versendet, überträgt die in der Arbeit vorgestellte Schnittstelle die Graphikbefehle simultan. Die dadurch erreichte Vermeidung redundanter Übertragungen bewirkt bereits einen besseren Durchsatz der Kommunikationskanäle und zusätzlich eine signifikante Verringerung der Prozessorbelastung des Applikationsrechners. Die freie gewordene Kapazität schafft wiederum die Voraussetzung für die Anwendung verschiedener Optimierungsverfahren zur weiteren Steigerung der graphischen Gesamtleistung der parallelen Schnittstelle. Dazu zählt neben der Zwischenspeicherung von Datensequenzen in einem Stream Cache die Filterung der OpenGL-Kommandoströme mit graphischen Culling-Verfahren. Speziell zum aktiv-stereoskopischen Rendern auf dem an der Professur vorhandenen zylindrischen Projektionssystem enthält die Schnittstelle Anpassungen für die Synchronisationshardware und die bildbasierte Korrektur der Parallaxe.

Für die schnelle Visualisierung großer Modelle werden sogenannte Echtzeit-Visualisierungsverfahren (real time rendering techniques) eingesetzt. Durch parallele Verarbeitung der Objektdaten auf Multicore-CPUs ist es möglich, die Geschwindigkeit der Darstellung gegenüber GPU-basierten Verfahren weiter zu erhöhen. Insbesondere wurde die Möglichkeit untersucht, das Occlusion-Culling mit Hilfe der CPU durchzuführen. Dabei konnte speziell das Worst-Case-Verhalten verbessert werden. Mit der Anzahl der Systemkomponenten (z.B. Trackingsystem, Beamer, Rechner) steigt die Trägheit (Latenz) des Gesamtsystems, was eine Echtzeitverarbeitung der Daten deutlich erschwert. Durch Bewegungsvorhersagen, die speziell an das Nutzerverhalten im Rahmen der Anwendung angepasst sind, können auftretende Latenzen kompensiert werden. Die Entwicklungen erfolgten im Kontext einer immersiven Tischtennissimulation. Tischtennis gehört zu den schnellsten Sportarten und repräsentiert somit eine anspruchsvolle Umgebung. Ein weiterer wichtiger Aspekt bei der Interaktion mit virtuellen Umgebungen ist die Natürlichkeit (Intuitivität) der Benutzeroberfläche. Durch eine möglichst direkte (aus der Realität bekannte) Umsetzung der Benutzerbewegungen in Systembefehle wird eine höchstmögliche Effektivität im Umgang mit dem System erzielt. Im Rahmen einer Designanwendung wurden Interaktionstechniken realisiert, die den alltäglichen Bewegungsabläufen nachempfunden sind.