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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

A Prototype For An Interactive And Dynamic Image-Based Relief Rendering System / En prototyp för ett interaktivt och dynamisktbildbaserat relief renderingssystem

Bakos, Niklas January 2002 (has links)
In the research of developing arbitrary and unique virtual views from a real- world scene, a prototype of an interactive relief texture mapping system capable of processing video using dynamic image-based rendering, is developed in this master thesis. The process of deriving depth from recorded video using binocular stereopsis is presented, together with how the depth information is adjusted to be able to manipulate the orientation of the original scene. When the scene depth is known, the recorded organic and dynamic objects can be seen from viewpoints not available in the original video.
32

Simulation des fonctions de texture bidirectionnelles

Yengui, 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.
33

Analyzing the Conceptual Integrity of Computing Applications Through Ontological Excavation and Analysis

Hsi, Idris 19 July 2005 (has links)
In the world of commercial computing, consumers are being inundated with baroque, bloated, and difficult-to-use computing applications, tools that use computational methods and technologies to perform tasks. Market forces demand that new versions of these applications implement more features, the user-accessible behaviors and services implemented by the application, than their predecessors or competitors. Ensuring that planned features required for market competitiveness enhance a computing application without these side effects first requires that we understand how these features contribute to the overall design and conceptual integrity of the application While conceptual integrity affects all aspect of the application, we are primarily interested in how an applications user-accessible features have been designed and implemented. To this end, we have developed a research framework, methodologies, and artifacts for measuring the conceptual integrity of a computing artifact from its theory of the world or its ontology. We use conceptual coherence, which we define as the degree to which an applications concepts are tightly related, as a first approximation for conceptual integrity. We claim the following: any computing application has a central or core set of concepts that are essential to that applications ontology and can be identified through analytical means; and concepts that are not essential to an applications ontology either exist to support core concepts or are peripheral to the ontology. Peripheral concepts reduce an applications conceptual coherence. We have developed the method of ontological excavation to identify the concepts in a computing application and model them as an ontology expressed as a semantic network. To identify core and peripheral concepts and to measure an ontologys conceptual coherence, we developed methodologies for ontological analysis. If usefulness depends on the conceptual integrity of an applications ontology such that it ensures high fitness to a problem domain, then we would expect that users solving problems in that domain will invoke the concepts integral to the solution more often than those concepts that do not. Thus, to validate our structural measures, we claim the following: the probable use of the application will invoke core concepts more frequently than peripheral concepts in the ontology.
34

Simulation des fonctions de texture bidirectionnelles

Yengui, 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.
35

Comparing unsupervised clustering algorithms to locate uncommon user behavior in public travel data : A comparison between the K-Means and Gaussian Mixture Model algorithms

Andrésen, Anton, Håkansson, Adam January 2020 (has links)
Clustering machine learning algorithms have existed for a long time and there are a multitude of variations of them available to implement. Each of them has its advantages and disadvantages, which makes it challenging to select one for a particular problem and application. This study focuses on comparing two algorithms, the K-Means and Gaussian Mixture Model algorithms for outlier detection within public travel data from the travel planning mobile application MobiTime1[1]. The purpose of this study was to compare the two algorithms against each other, to identify differences between their outlier detection results. The comparisons were mainly done by comparing the differences in number of outliers located for each model, with respect to outlier threshold and number of clusters. The study found that the algorithms have large differences regarding their capabilities of detecting outliers. These differences heavily depend on the type of data that is used, but one major difference that was found was that K-Means was more restrictive then Gaussian Mixture Model when it comes to classifying data points as outliers. The result of this study could help people determining which algorithms to implement for their specific application and use case.
36

Energy and Water Usage in the Manufacturing Industry : A study case to analyse, compare and decide where to reduce energy and water utilization

López, Jorge, Rincón Franco, Yully Constanza January 2020 (has links)
Increasing concern about global climate change has led to a growing interest in energy usage and water consumption. It is well known that changes in consumption habits lead to more efficient use of energy and water sources. Nowadays, globalization, environmental concerns, and the shortage of resources have led to an increase of stakeholder pressure on companies to expand their focus to sustainability. Also, the high impact that the savings can have in the financial status of the company. It is encouraging the headboards to study and improve the ways water and energy are being used within the processes. Significant economic savings and benefits for the environment could be achieved with slight changes in the company. As an overview, this project starts with the extraction of data from a platform for energy management in an industrial company. Then, it goes through the understanding of the energy and water usage data set. Later, a methodology to handle and process the data will be set. It is intending to extract relevant information using clustering. The idea is to compare the usage profiles between different factories, using key performance indicators and reducing the initial data set. Once the benchmarking is performed, some critical parameters will be selected to support the decision-making process related to investments to reduce the energy usage and water consumption in a specific location. Finally, the case of study will be implemented with the measurements from Alfa Laval. We will study how, from daily measurements with a very low investment and using the proper algorithms and methodologies, the main behaviours and features in an industrial location can be extracted from the utilization data. These characteristics can be used to develop strategies or productions schemes based on the interests of the energy manager and the company.
37

On form thinking in knitwear design

Landahl, Karin January 2013 (has links)
This licentiate thesis presents and discusses experimental explorations in search for new methods of form-thinking within the knitwear design process. The position of textile knitting techniques is somewhat ambiguous. This is because they are not only concerned with creating the textile material, but also with the form of the garment as these two are created in the same process. Consequently, the common perception of form and material as two separate design parameters can be questioned when it comes to knitting. Instead, we may view it as a design process that has a single design parameter; a design process in which the notion of form provides the conceptual foundation. Through conducting a series of design experiments using knitting and crochet techniques, the notion of form was explored from the perspective of the way in which we make a garment. The outcome of the experiments showed that there are possibilities for development of alternative working methods in knitwear design by viewing form in terms of topological invariants rather than as abstract geometrical silhouettes. If such a notion, i.e. a notion of a more concrete geometry, were to be implemented in the design process for knitwear, it would provide another link between action and expression that could deepen our understanding of the design potential of knitting techniques and provide the field with new expressions and gestalts.
38

Modélisation d'objets 3D par fusion silhouettes-stéréo à partir de séquences d'images en rotation non calibrées

Hernández Esteban, Carlos 04 May 2004 (has links) (PDF)
Nous présentons une nouvelle approche pour la modélisation d'objets 3D de haute qualité à partir de séquences d'images en rotation partiellement calibrées. L'algorithme est capable: de calibrer la caméra (la pose et la longueur focale), de reconstruire la géométrie 3D et de créer une carte de texture. Par rapport à d'autres méthodes plus classiques, le calibrage est réalisé à partir d'un ensemble de silhouettes comme seule source d'information. Nous développons le concept de cohérence d'un ensemble de silhouettes généré par un objet 3D. Nous discutons d'abord la notion de cohérence de silhouettes et définissons un critère pratique pour l'estimer. Ce critère dépend à la fois des silhouettes et des paramètres des caméras qui les ont générées. Ces paramètres peuvent être estimés pour le problème de modélisation 3D en maximisant la cohérence globale des silhouettes. La méthode de reconstruction 3D est fondée sur l'utilisation d'un modèle déformable classique, qui définit le cadre dans lequel nous pouvons fusionner l'information de la texture et des silhouettes pour reconstruire la géométrie 3D. Cette fusion est accomplie en définissant deux forces basées sur les images: une force définie par la texture et une autre définie par les silhouettes. La force de texture est calculée en deux étapes: une approche corrélation multi-stéréo par décision majoritaire, et une étape de diffusion du vecteur gradient (GVF). En raison de la haute résolution de l'approche par décision majoritaire, une version multi-résolution du GVF a été développée. En ce qui concerne la force des silhouettes, une nouvelle formulation de la contrainte des silhouettes est dérivée. Elle fournit une manière robuste d'intégrer les silhouettes dans l'évolution du modèle déformable. A la fin de l'évolution, cette force fixe les contours générateurs du modèle 3D. Finalement, une carte de texture est calculée à partir des images originales et du modèle 3D reconstruit.
39

Coping e aspectos psicossociais associados ao tratamento cirúrgico da obesidade mórbida em longo prazo / Coping and psychosocial aspects associated to surgical treatment of morbid obesity in the long-term

Camargo, Maria Adelaide Gallo Ferreira de 22 April 2013 (has links)
A obesidade mórbida é uma doença crônica, de causas multifatoriais e de tratamento difícil, que apresenta alto risco para a saúde. A cirurgia bariátrica tem se mostrado a opção mais eficaz de tratamento para a redução das comorbidades, mas pode ser seguida de problemas físicos que causam dificuldades nos relacionamentos interpessoais, dificultando a adaptação psicossocial do indivíduo ao meio ambiente social. Em longo prazo o sucesso depende da mudança de comportamento, principalmente em relação aos hábitos alimentares, da complementação necessária de vitamina e sal mineral e da prática regular de exercícios físicos de forma contínua. Ao longo do tempo, fatores psicológicos exercem influência sobre a capacidade de o paciente adaptar-se às condições de vida para a necessária manutenção da redução do peso corpóreo. O período de tempo decorrido após a cirurgia, entre 4 e 12 anos, foi investigado em uma amostra composta por 75 pessoas; todos os pacientes foram operados com a utilização da mesma técnica cirúrgica e pelo mesmo cirurgião, também coordenador da equipe multidisciplinar. A idade mínima foi de 26 e máxima de 76 anos. Foram utilizados três instrumentos de avaliação psicológica com a seguinte finalidade: medir o Nível de Coping e Habilidade Social; pesquisar a opinião dos sujeitos de forma categorizada pelo método do Discurso do Sujeito Coletivo, mediante a aplicação de instrumento desenvolvido especificamente para a presente investigação; e avaliar a insatisfação com a imagem corporal pela aplicação da Escala de Silhuetas de Stunkard (SMT). Os resultados, tratados estatisticamente, revelaram pessoas com médio e alto nível de coping e habilidade social, que demonstram condições adequadas de enfrentamento e de formação de vínculos sociais; contudo encontram-se acima do peso esperado, cujo Índice de Massa Corporal indica situação de obesidade grau 1, de acordo com a OMS. Estão insatisfeitos com a silhueta atual, conscientes de que se encontram acima do peso desejado, mas valorizam altamente a opção que fizeram pela realização da cirurgia bariátrica, que lhes proporcionou autonomia, elevação da autoestima e os livrou da discriminação social. A discussão se fez com o aporte teórico de conceitos extraídos da psicologia cognitiva, da psicologia positiva, da psicanálise, da sociologia e da antropologia. Concluiu-se que a gastroplastia produz efeitos colaterais fisiológicos perenes, como engasgos, vômitos e mal-estar, que dificultam, mas não impedem, a adaptação psicossocial; que os entrevistados têm consciência de que o peso e a imagem não correspondem ao padrão esperado por eles, contudo apresentam adequado sentido de adaptação social; e para eles a cirurgia bariátrica ocupa um lugar que envolve representações mentais de rito de passagem, como transposição metafórica para um novo status da condição social / Morbid obesity is a chronic condition, of multi-factor causes, difficult to treat and which carries a high risk of health problems. Bariatric surgery has been shown to be the most effective treatment for reducing comorbidities, but it may be followed by physical problems that cause difficulties in interpersonal relationships, hindering the individual\'s psychosocial adaptation to the social environment. Long-term success depends on changing behavior especially in relation to food habits, use of vitamin supplements and mineral salt, as appropriate, and regular practice of physical activity. Over time, psychological factors may influence the ability of patients to adapt to their living conditions and maintain the weight loss. A period of time after surgery between 4 and 12 years was investigated in a sample of 75 people. All patients underwent the procedure using the same surgical technique, performed by the same surgeon and coordinator of the multidisciplinary team. The patients were aged between 26 years and 76 years. Three psychometric measures were used to investigate the level of coping and the participants\' opinion through an interview conducted in a categorized manner: the method of Discourse of the Collective Subject, including a questionnaire developed specifically for this research, and the assessment of body image dissatisfaction according to the Stunkard Silhouette Matching Task (SMT). The results, analyzed in statistical terms, revealed individuals with medium and high levels of coping and social skills, who demonstrate appropriate coping conditions and ability to establish social bonds. Nevertheless, they are still above the expected weight and present body mass indexes that indicate a status of grade 1 obesity, according to the WHO. These individuals are dissatisfied with their current silhouettes, aware that they are above the desired weight, but strongly value the choice they made for bariatric surgery that gave them autonomy and increased selfesteem, protecting them against social prejudice. The discussion was based on theoretical concepts drawn from cognitive psychology, positive psychology, psychoanalysis, sociology and anthropology. Conclusions: gastroplasty produces continuing physiological side effects that make psychological and social adaptation difficult, although it does not prevent them from occurring; the respondents are aware that their weight and body image do not match the pattern of their expectations, nevertheless they do present an adequate sense of social adaptation and, for them, bariatric surgery occupies a place that involves mental representations of rite of passage, as a metaphorical transposition to a new social status
40

Image-based Capture and Modeling of Dynamic Human Motion and Appearance

Birkbeck, Neil Aylon Charles Unknown Date
No description available.

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