131 |
Simulation des fonctions de texture bidirectionnellesYengui, Mohamed Yessine 01 1900 (has links)
Le réalisme des objets en infographie exige de simuler adéquatement leur apparence
sous divers éclairages et à différentes échelles. Une solution communément adoptée par les chercheurs consiste à mesurer avec l’aide d’appareils calibrés la réflectance d’un échantillon de surface réelle, pour ensuite l’encoder sous forme d’un modèle de réflectance (BRDF) ou d’une texture de réflectances (BTF).
Malgré des avancées importantes, les données ainsi mises à la portée des artistes
restent encore très peu utilisées. Cette réticence pourrait s’expliquer par deux raisons
principales : (1) la quantité et la qualité de mesures disponibles et (2) la taille des données.
Ce travail propose de s’attaquer à ces deux problèmes sous l’angle de la simulation.
Nous conjecturons que le niveau de réalisme du rendu en infographie produit déjà des
résultats satisfaisants avec les techniques actuelles. Ainsi, nous proposons de précalculer
et encoder dans une BTF augmentée les effets d’éclairage sur une géométrie, qui sera
par la suite appliquée sur les surfaces. Ce précalcul de rendu et textures étant déjà bien
adopté par les artistes, il pourra mieux s’insérer dans leurs réalisations.
Pour nous assurer que ce modèle répond aussi aux exigences des représentations
multi-échelles, nous proposons aussi une adaptation des BTFs à un encodage de type
MIP map. / The realism of objects in computer graphics requires adequate simulation of their
appearence under different light/view directions and at various scales. A solution commonly
adopted by researchers consists in measuring the reflectance of a real surface by
means of calibrated devices. The measured data is encoded in the form of a reflectance
model (BRDF) or a texture of reflectance (BTF). Despite significant progress in this area,
the measured appearence data remain very infrequently used. This reluctance could be
explained by two main reasons: (1) the limited number of high-quality measured materials
and (2) the huge storage space required by the data. In this work, we suggest
resolving these two problems from the angle of simulation. We consider that the level of
realism in rendered images already produces satisfactory results with current techniques.
Therefore, we propose to precompute and encode the effects of lighting on a completely
synthetic micro-geometry, which will be applied on surfaces. This production pipeline
being already well adopted by artists, it should better fit into their realizations. To ensure
that this model also respects the requirements of multi-scale representations, we also
propose an adaptation of the BTF to a MIP map encoding.
|
132 |
Effects of entomopathogenic fungi used as plant inoculants on plant growth and pest control / Efeitos da utilização de fungos entomopatogênicos como inoculantes no crescimento de plantas e controle de pragasCanassa, Fernanda 29 April 2019 (has links)
Entomopathogenic fungi (EPF) of the genera Metarhizium and Beauveria are able to endophytically colonize a wide variety of plant species, providing protection against arthropod pests; besides increasing the plant development; and act as phytopathogen antagonists. The main objective of the present project was to evaluate the potential of entomopathogenic fungi as plant inoculants against the two-spotted spider mite Tetranychus urticae and the effects on plant growth promotion. Tritrophic effects were also studied, by evaluating prey consumption and feeding behavior of the predatory mite Phytoseiulus persimilis. The evaluated strategy has several potential benefits compared to the sole use of EPF as contact biocontrol agents, as it may control both pests and phytopathogens; be compatible with other natural enemies; provide limited exposure of fungal propagules to adverse environmental conditions, and accelerate seed emergence and plant growth. Considering this, the effects of seed inoculation using two isolates of Metarhizium robertsii and Beauveria bassiana were evaluated at University of Copenhagen, Denmark, on plant development (i.e. biomass and yield) and T. urticae population growth in a model system with bean plants under greenhouse conditions. Effects on feeding performance of P. persimilis were also studied in laboratory conditions. In Brazil, inoculation studies with EPF were conducted at ESALQ/USP with strawberry plants in greenhouse conditions and in the field in four commercial production areas of strawberries in Atibaia-SP and Senador Amaral-MG. In greenhouse studies, the effects of 15 isolates of Metarhizium spp., 5 isolates of B. bassiana and 5 of Cordyceps (= Isaria) fumosorosea were studied, whereas in the commercial area one isolate of Metarhizium and Beauveria was used. Strawberry roots were inoculated by submersion in fungal suspensions, and the population growth of spider mites, while plants development was assessed by measuring root lengths, biomass of roots and leaves, and the strawberry fruit weight. The results showed a significant reduction in T. urticae population and in general better plant development in both crops. The production of string beans and strawberry fruits were higher in inoculated plants than in non-inoculated plants. There was no difference in predation rate and feeding behavior of the predator mite P. persimilis towards T. urticae from fungal inoculated and uninoculated plants. In the commercial strawberry production areas there were significantly lower populations of T. urticae and fewer symptoms of plant diseases on plants in the fungal treated beds compared to plants in untreated beds. The results of this project bring a new perspective on the use of Metarhizium and Beauveria as plant protecting agents revealing that the use of entomopathogenic fungi as plant inoculants may be a promising strategy. / Fungos entomopatogênicos dos gêneros Metarhizium e Beauveria são capazes de colonizar endofiticamente uma ampla variedade de espécies de plantas e conferir à estas, proteção contra artrópodes pragas; além de acelerar o seu desenvolvimento; e atuar como antagonistas de fitopatógenos. O objetivo geral deste projeto foi avaliar o potencial de fungos entomopatogênicos como inoculantes contra o ácaro rajado Tetranychus urticae e seus efeitos na promoção de crescimento de plantas. O efeito tri-trófico no consumo e comportamento alimentar do ácaro predador Phytoseiulus persimilis também foi estudado. A estratégia avaliada traz vários potenciais benefícios comparado ao uso exclusivo de fungos entomopatogênicos como agentes de controle biológico de contato, como o controle duplo de pragas e fitopatógenos; compatibilidade com outros inimigos naturais; menor exposição de propágulos às condições ambientais adversas, além de acelerar a emergência de sementes e o crescimento de plantas. Diante disso, os efeitos da inoculação de sementes usando dois isolados de Metarhizium robertsii e Beauveria bassiana foram avaliados na Universidade de Copenhagen, Dinamarca, na promoção de crescimento das plantas (biomassa e produção) e no crescimento populacional de T. urticae em um sistema modelo com plantas de feijão em casa-de-vegetação. Efeitos no comportamento alimentar de P. persimilis foram também estudados em condições de laboratório. No Brasil, estudos foram conduzidos na ESALQ/USP com plantas de morangueiro em casa-de-vegetação e em quatro áreas de produção comercial de morangueiro em Atibaia-SP e Senador Amaral-MG. Nos estudos em casa-de-vegetação, os efeitos de 15 isolados de Metarhizium spp., 5 de B. bassiana e 5 de Cordyceps (= Isaria) fumosorosea foram estudados, enquanto em área comercial um isolado de Metarhizium e Beauveria foram utilizados. Raízes de morangueiro foram inoculadas por imersão em suspensões fúngicas, e foram avaliados o crescimento populacional do ácaro rajado e o desenvolvimento das plantas, quantificando o comprimento de raiz, biomassa de raiz e de parte aérea, e massa de frutos de morango. Os resultados mostraram redução significativa na população de T. urticae e em geral melhor desenvolvimento das plantas nas duas culturas. A produção de vagens em plantas de feijão e de frutos de morango foram superiores nas plantas inoculadas em relação às não inoculadas. Não se observou diferenças na taxa de predação e comportamento alimentar do ácaro predador P. persimilis quando oferecidos T. urticae provenientes de plantas inoculadas e não inoculadas. Em campo foram observadas populações significativamente menores de T. urticae e menos sintomas de doenças nas plantas inoculadas com os fungos, comparado às plantas não inoculadas. Os resultados obtidos por este projeto trazem uma nova perspectiva do uso de Metarhizium e Beauveria como agentes protetores de plantas revelando que a utilização de fungos entomopatogênicos como inoculantes pode ser uma estratégia promissora.
|
133 |
Localização de tanques de armazenagem de álcool combustível no Brasil: aplicação de um modelo matemático de otimização / Ethanol storage tanks location in Brazil: a mixed integer program model applicationXavier, Carlos Eduardo Osório 15 April 2008 (has links)
O objetivo principal deste trabalho foi criar um modelo matemático para determinar, em nível estratégico, os locais no Brasil mais apropriados à instalação de tanques de álcool combustível (anidro e hidratado) e seus respectivos volumes. O modelo de programação inteira-mista desenvolvido baseou-se na organização do sistema de distribuição de álcool, enfocando sua logística, e considerando questões de oferta, demanda, infra-estrutura de transporte e armazenagem, além de custos de transporte, armazenagem e investimentos em tanques. O modelo foi formulado considerando o horizonte temporal dos meses do ano-safra canavieiro de 2006/2007. Essa formulação reflete as sazonalidades de produção, demanda e estoques do álcool. O modelo de transporte foi enfatizado na minimização dos custos logísticos da cadeia distribuição de álcool combustível dos produtores aos consumidores. Dois cenários e a análise de sensibilidade de suas respostas abordaram a questão estocástica do problema. O primeiro analisou o panorama atual do mercado de álcool, logo não considerou a possibilidade de criação de novos tanques. A idéia desse cenário foi apresentar a consistência da modelagem e ressaltar as condições de infra-estrutura existente de transporte e armazenagem para álcool combustível. Foi feita uma análise de sensibilidade em relação a custos de transporte e restrições de armazenagem para checagem das respostas e para a comparação das práticas atuais de mercado. No segundo cenário, considerou-se a possibilidade de criação de novos tanques procurando identificar os locais mais apropriados para construção dessas estruturas e seu dimensionamento. A análise de sensibilidade em relação a custos de transporte e restrições de armazenagem foi feita para confirmar o potencial de cada localização. Os resultados indicaram a localização inapropriada das bases de distribuição de álcool no país. Destacaram-se também os baixos níveis de fretes de transferência em função das limitações de infraestrutura do sistema de distribuição de álcool. Tanto que as principais localizações de novos tanques disseram respeito a bases no interior da região Centro-Sul, destinos cujos custos de transporte de coleta e entrega são mais competitivos. Em relação aos novos tanques de álcool hidratado houve a indicação das cidades de: Cascavel - PR, Umuarama - PR, Maringá - PR, Lages - SC, Sinop - MT, Limeira - SP e Sorocaba - SP. Para o caso do álcool anidro os novos investimentos sugeridos foram nas cidades de: Londrina - PR, Cascavel - PR, Guarapuava - PR, Lajes - SC, Santa Maria - RS, Araçatuba - SP, Sinop - MT, Vilhena - RO, Montes Claros - MT, Dourados - MS, Gurupi - TO e Teresina - PI. Somado a isso houve a alocação de praticamente todo o custo de armazenagem às usinas. Finalmente, as soluções para a localização de novos investimentos dos tanques de álcool foram todas em regiões de bases de distribuição, já que as usinas estão bem servidas em relação à capacidade de armazenagem. / The main purpose of this research is to develop a mathematical model intended for strategic analysis of the optimal location and considering suitable volumes for storage ethanol (anhydrous and hydrous) tanks. The Mixed Integer Program - MIP model was based on Brazilian ethanol distribution system. The model considered market parameters as supply, demand, and infrastructure parameters on transportation, storage values as well as their expenses. New construction ethanol tanks expenses also were considered. The months along the sugarcane crop year period of 2006/2007 were referred into the modeling formulation. This formulation allows a seasonal storage, production and demand patterns analysis. Transportation model is the main concern in the total logistics cost minimization from producers to consumers. The model stochastic formulation was elaborated by creating two simulated scenarios and developing a sensitivity analysis. The purpose of the first scenario was to check the model consistency and explore the current ethanol transport and storage infrastructure without considering the possibility of new tank installation. Based on these results, a sensitivity analysis regarding transportation expenses and storage restrictions was elaborated in order to make a comparison with current market practices. In the second scenario, it was considered the construction of new ethanol tanks and the identification of the most suitable places bearing in mind volume capacities. Based on these results, a sensitivity analysis regarding transportation expenses and storage restrictions was elaborated in order to check each location consistency. Results indicated that mills are mostly responsible for ethanol (anhydrous and hydrous) storages maintenance types and that the existing geographic organization of terminals and fuel distributors is inappropriate for ethanol distribution in Brazil. Transportation low flows among terminals and fuel distributors also indicated lack of a better infrastructure for ethanol distribution. The model indicated that main location results for installation of new tanks would be located especially in the countryside of the centersouth states, where allocation and distribution of ethanol from mills to the consumer market would be more competitive. In relation to the new hydrous ethanol tanks, the model indicated appropriated locations for the cities of: Cascavel - PR, Umuarama - PR, Maringá - PR, Lages - SC, Sinop - MT, Limeira - SP e Sorocaba - SP. In the other hand, for anhydrous ethanol, new investments suggested in: Londrina - PR, Cascavel - PR, Guarapuava - PR, Lajes - SC, Santa Maria - RS, Araçatuba - SP, Sinop - MT, Vilhena - RO, Montes Claros - MT, Dourados - MS, Gurupi - TO e Teresina - PI. Finally, the model indicated that the best locations for the establishment of new ethanol tanks would be located in fuel distributors\' bases, once results confirmed that mills have enough storage capacity.
|
134 |
Développement d'architectures innovantes associant capteurs acoustiques et matériaux polymères à empreintes moléculaires pour la détection de biomarqueurs de cancer / Association of a Love wave sensor to molecularly imprinted polymer for real time detection of colorectal cancer biomarkersLebal, Naîma 14 December 2015 (has links)
Les chiffres des statistiques du cancer colorectal en France et dans le mondemontrent la nécessité de développement de plateformes technologiques plus rapides,sensibles et spécifiques pour assurer le diagnostic du cancer. Un diagnostic rapide va ainsiaider à améliorer l’état de santé et réduire le temps d’attente des résultats qui peut être ungrand facteur de stress pour les patients. L’analyse des biomarqueurs dans le sang, lesurines et autres fluides corporels est l’une des méthodes appliquées pour la détectionprécoce de la maladie. Dans le cadre de ce projet des nucléosides urinaires ont été identifiéscomme biomarqueurs pour le cancer colorectal. Financée par l’Agence Nationale de laRecherche (ANR), à travers le projet CancerSensor (programme TECSAN), cette thèse s’estdéroulée au sein de l’équipe MDA (Microsystèmes de Détection Acoustique) du laboratoireIMS. Dans le cadre de ce projet, nous avons proposé une solution technologique dedétection et de suivi de biomarqueurs du cancer colorectal. Notre choix de la stratégie dedétection s’est porté sur les polymères à empreintes moléculaires comme élément dereconnaissance des biomarqueurs. Celui-ci sera associé à un transducteur acoustique àondes de Love mis au point lors de travaux précédents au sein de l’équipe MDA. Lebiocapteur ainsi développé va cibler les nucléosides mis en évidence pour le cancercolorectal. / Colorectal cancer statistics in France and all over the world demonstrate theneed for fast, sensitive and specific technological platforms development for cancerdiagnosis. A rapid diagnosis will improve the patients’ health status and reduce the resultswaiting time which could be a great stress factor. Biomarkers analysis in blood, urine andother body fluids is recognized as one of the applied methods for early cancer detection. Inframe of this project, urinary nucleosides have been identified as colorectal cancerbiomarkers. Funded by the National Research Agency (ANR), through the cancer sensorproject (TECSAN program), this thesis was carried out in IMS laboratory. Hence, a colorectalcancer biomarkers detection and monitoring technological solution has been proposed. Inour detection strategy, Molecularly Imprinted Polymers (MIP) has been identified asbiomarker recognition element. The MIP layer has been associated to Love Wave acoustictransducer. This biosensor will sense the identified colorectal cancer nucleosides.
|
135 |
Higgs Recoil Mass and Cross-Section Analysis at ILC AND Calibration of the CALICE SiW ECAL PrototypeLi, H. 22 October 2009 (has links) (PDF)
Le sujet principal de cette thèse porte sur les mesures de la masse de recul du boson de Higgs et de sa section efficace en utilisant la réaction de Higgs-strahlung avec Z → µ + µ− et e+e−, basées sur la simulation détaillée du détecteur ILD. L'étude a été conduite pour un Higgs de 120 GeV de masse, à une énergie de 250 GeV dans le centre de masse pour une luminosité intégrée de 250 fb−1 . La précision obtenue est de 28 MeV sur la mesure de la masse du Higgs et 2.0% sur celle de la section efficace en combinant les canaux de désintégration. Cette étude prouve que le bruit de fond peut être largement réduit et que les résultats sont sensibles à la configuration de l'accélérateur. L'analyse et ses résultats sont inclus dans le ILD Letter of Intent. Le second sujet de la thèse est la calibration en MIPs du prototype de ECAL Silicium - Tungstène d´eveloppé par la collaboration CALICE. Les constantes de calibration sont extraites des données des tests en faisceau effectués au FNAL en 2008 et sont stables par rapport aux données prises au CERN en 2006.
|
136 |
Nucleic Acid Based Pathogen DiagnosticsAkhras, Michael S. January 2008 (has links)
Pathogenic organisms are transmitted to the host organism through all possible connected pathways, and cause a myriad of diseases states. Commonly occurring curable infectious diseases still impose the greatest health impacts on a worldwide perspective. The Bill & Melinda Gates Foundation partnered with RAND Corporation to form the Global Health Diagnostics Forum, with the goal of establishing and interpreting mathematical models for what effects a newly introduced point-of-care pathogen diagnostic would have in developing countries. The results were astonishing, with potentially millions of lives to be saved on an annual basis. Golden standard for diagnostics of pathogenic bacteria has long been cultureable medias. Environmental biologists have estimated that less than 1% of all bacteria are cultureable. Genomic-based approaches offer the potential to identify all microbes from all the biological kingdoms. Nucleic acid based pathogen diagnostics has evolved significantly over the past decades. Novel technologies offer increased potential in sensitivity, specificity, decreased costs and parallel sample management. However, most methods are confined to core laboratory facilities. To construct an ultimate nucleic acid based diagnostic for use in areas of need, potential frontline techniques need to be identified and combined. The research focus of this doctoral thesis work has been to develop and apply nucleic acid based methods for pathogen diagnostics. Methods and assays were applied to the two distinct systems i) screening for antibiotic resistance mutations in the bacterial pathogen Neisseria gonorrhoeae, and ii) genotype determination of the cancer causative Human Papillomavirus (HPV). The first part of the study included development of rapid, direct and multiplex Pyrosequencing nucleic acid screenings. With improved methodology in the sample preparation process, we could detect an existence of multiple co-infecting HPV genotypes at greater sensitivities than previously described, when using the same type of methodology. The second part of the study focused on multiplex nucleic acid amplification strategies using Molecular Inversion Probes with end-step Pyrosequencing screening. The PathogenMip assay presents a complete detection schematic for virtually any known pathogenic organism. We also introduce the novel Connector Inversion Probe, a padlock probe capable of complete gap-fill reactions for multiplex nucleic acid amplifications. / Patogena organismer smittas till värd organismen genom alla möjliga kontaktnätverk och skapar en mångfald olika sjukdomstillstånd. Dock är det fortfarande vanligt förekommande behandlingsbara infektiösa sjukdomar som orsakar den största hälsoförlusten, sett från ett globalt perspektiv. Bill och Melinda Gates Stiftelsen samarbetade med RAND kooperation för att forma “The Global Health Diagnostics Forum”. Deras mål var att etablera och analysera matematiska modeller för vilka effekter en ny diagnostisk metod utrustat för fältarbete skulle ha i utvecklingsländer. Resultaten var häpnadsveckande, med potentiellt miljoner av liv som skulle kunna räddas på en årlig basis. Den etablerade standarden för diagnostik av patogena bakterier har länge varit kultiveringsmedia baserad. Miljö specialiserade biologer har estimerat att mindre än 1 % av alla bakterie arter går att kultivera. Dock erbjuder genetiska analyser potentialen att kunna identifiera alla mikrober från alla de biologiska rikena. Nukleinsyrebaserade diagnostiska metoder har märkbart förbättrats över de senaste årtionden. Nya tekniker erbjuder utökad sensitivitet, selektivitet, sänkta kostnader och parallella analyser av patient prover. Dock är de flesta metoderna begränsade till standardiserade laboratoriemiljöer. För att konstruera en väl fungerande diagnostisk fältutrustning för användning i problem områden, behöver världsledande tekniker identifieras och kombineras. Fokuseringsområdet för denna doktorsavhandling har varit att utveckla och utföra nukleinsyrebaserade metoder för patogen diagnostik. Metoder och experimentella utförande applicerades på två distinkta system i) sökning av antibiotika resistens relaterade mutationer i den patogena bakterien Neisseria gonorrhoeae och ii) genotypning av det cancer orsakande Humana Papillomaviruset (HPV). Den första delen av studien inriktade sig mot utveckling av snabba, direkta och multiplexa Pyrosekvenserings baserade nukleinsyreanalyser. Med förbättrad provprepareringsmetodologi kunde vi detektera multipla HPV infektioner med högre sensitivitet än vad tidigare beskrivits med liknande metodologi. Den andra delen av studien fokuserades på multiplexa nukleinsyre amplifikationer med “Molecular Inversion Probe” tekniken med sista steg Pyrosekvenserings analys. “PathogenMip assay” erbjuder ett komplett detektionsprotokoll för alla kända patogena organismer. Vi introducerar även den nya “Connector Inversion Probe”, en “Padlock Probe” kapabel att genomföra kompletta gap fyllningar för multiplex nukleinsyre amplifiering. / QC 20100624
|
137 |
Développement d'un biocapteur associant dispositif à onde de Love et polymères à empreintes moléculaires : caractérisation sous gazOmar Aouled, Nima 16 July 2013 (has links) (PDF)
Ces travaux de recherches concernent l'association de la technologie des polymères à empreintes moléculaires aux dispositifs acoustiques à onde de Love afin de réaliser un biocapteur dans le cadre d'un projet ANR Tecsan. La première partie de ces travaux de thèse a dressé plus spécifiquement la mise au point d'un protocole de dépôt localisé de polymères imprimés (MIP) et non imprimés (NIP) en films minces compatibles avec la propagation de l'onde élastique. La seconde aprtie des travaux a visé une caractérisation des films et des capteurs ainsi réalisés, par microscopie à balayage et apr mesures de détection sous gaz. Des éléments relatifs aux propriétés mécaniques (porosité, surfaces spécifiques) des MIPs et NIPs, avant extraction de la molécule cible, puis après extraction et après recapture, ont permis de valider le principe du capteur, ouvrant la voie à l'application en milieu liquide.
|
138 |
Contributions à la conception de réseau de service en transportSchrenk, Susann 23 September 2010 (has links) (PDF)
Dans cette thèse, nous nous sommes intéressés à deux problèmes industriels dans le domaine du transport. Le premier est un problème de conception de réseau de service avec gestion de ressources pour un transport régulier de fret. Le second est le problème de gestion de perturbation dans le domaine aérien, sujet du challenge ROADEF'2009. Dans les deux cas, il s'agit de problèmes pratiques difficiles qui comportent des contraintes complexes non standard. Le défi est d'autant plus marqué que les instances à résoudre sont de grandes tailles et que les problèmes comportent une dimension temporelle forte. Nous avons analysé la complexité des problèmes en étudiant la complexité de problèmes combinatoires purs, sous-problèmes au cœur de nos problèmes industriels. Nous présentons différentes formulations MIP du problème de conception d'un réseau de service avec gestion de flotte. Il ressort de notre étude que les formulations à base de cycles pour les véhicules sont très prometteuses. Finalement, nous présentons notre contribution au challenge ROADEF'2009. Nous proposons une méthode de résolution rapide, basée sur une décomposition, permettant de trouver de bonnes solutions à un problème industriel complexe en temps limité.
|
139 |
Simulation des fonctions de texture bidirectionnellesYengui, Mohamed Yessine 01 1900 (has links)
Le réalisme des objets en infographie exige de simuler adéquatement leur apparence
sous divers éclairages et à différentes échelles. Une solution communément adoptée par les chercheurs consiste à mesurer avec l’aide d’appareils calibrés la réflectance d’un échantillon de surface réelle, pour ensuite l’encoder sous forme d’un modèle de réflectance (BRDF) ou d’une texture de réflectances (BTF).
Malgré des avancées importantes, les données ainsi mises à la portée des artistes
restent encore très peu utilisées. Cette réticence pourrait s’expliquer par deux raisons
principales : (1) la quantité et la qualité de mesures disponibles et (2) la taille des données.
Ce travail propose de s’attaquer à ces deux problèmes sous l’angle de la simulation.
Nous conjecturons que le niveau de réalisme du rendu en infographie produit déjà des
résultats satisfaisants avec les techniques actuelles. Ainsi, nous proposons de précalculer
et encoder dans une BTF augmentée les effets d’éclairage sur une géométrie, qui sera
par la suite appliquée sur les surfaces. Ce précalcul de rendu et textures étant déjà bien
adopté par les artistes, il pourra mieux s’insérer dans leurs réalisations.
Pour nous assurer que ce modèle répond aussi aux exigences des représentations
multi-échelles, nous proposons aussi une adaptation des BTFs à un encodage de type
MIP map. / The realism of objects in computer graphics requires adequate simulation of their
appearence under different light/view directions and at various scales. A solution commonly
adopted by researchers consists in measuring the reflectance of a real surface by
means of calibrated devices. The measured data is encoded in the form of a reflectance
model (BRDF) or a texture of reflectance (BTF). Despite significant progress in this area,
the measured appearence data remain very infrequently used. This reluctance could be
explained by two main reasons: (1) the limited number of high-quality measured materials
and (2) the huge storage space required by the data. In this work, we suggest
resolving these two problems from the angle of simulation. We consider that the level of
realism in rendered images already produces satisfactory results with current techniques.
Therefore, we propose to precompute and encode the effects of lighting on a completely
synthetic micro-geometry, which will be applied on surfaces. This production pipeline
being already well adopted by artists, it should better fit into their realizations. To ensure
that this model also respects the requirements of multi-scale representations, we also
propose an adaptation of the BTF to a MIP map encoding.
|
140 |
Ranking Units By Target-direction-set Value Efficiency Analysis And Mixed Integer ProgrammingBuyukbasaran, Tayyar 01 April 2005 (has links) (PDF)
In this thesis, two methods are proposed in order to rank units: Target-direction-set value efficiency analysis (TDSVEA) and mixed integer programming (MIP) technique. Besides its ranking ability based on preferences of a decision maker (DM), TDSVEA, which modifies the targeted projection approach of Value Efficiency Analysis (VEA) and Data Envelopment Analysis (DEA), provides important information to analyzer: targets and distances of units from these targets, proposed input allocations in order to project these targets, the lack of harmony between the DM and the manager of the unit etc. In MIP technique, units select weights of the criteria from a feasible weight space in order to outperform maximum number of other units. Units are then ranked according to their outperforming ability. Mixed integer programs in this technique are simplified by domination and weight-domination relations. This simplification procedure is further simplified using transitivity between relations. Both TDSVEA and MIP technique are applied to rank research universities and these rankings are compared to those of other ranking techniques.
|
Page generated in 0.0292 seconds