Les structures planaires de grandes tailles sont de plus en plus utilisées dans les applications des satellites et des radars. Deux grands types de ces structures à savoir les FSS et les Reflectarrays sont particulièrement les plus intéressants dans les domaines de la conception RF. Mais en raison de leur grande taille et de la complexité des cellules élémentaires, l‘analyse complète de ces structures nécessite énormément de mémoire et des temps de calcul excessif. Par conséquent, les techniques classiques basées sur maillage linéaire soit ne parviennent pas à simuler de telles structures soit, exiger des ressources non disponibles à un concepteur d'antenne. Une technique appelée « technique par changement d'échelle » tente de résoudre ce problème par partitionnement de la géométrie du réseau par de nombreux domaines imbriqués définis à différents niveaux d'échelle du réseau. Le multi-pôle par changement d'échelle, appelé « Scale changing Network (SCN) », modélise le couplage électromagnétique entre deux échelles successives, en résolvant une formulation intégral des équations de Maxwell par une technique basée sur la méthode des moments. La cascade de ces multi-pôles par changement d'échelle, permet le calcul de la matrice d'impédance de surface de la structure complète qui peut à son tour être utilisées pour calculer la diffraction en champ lointain. Comme le calcul des multi-pôles par changement d'échelle est mutuellement indépendant, les temps d'exécution peuvent être réduits de manière significative en parallélisant le calcul. Par ailleurs, la modification de la géométrie de la structure à une échelle donnée nécessite seulement le calcul de deux multi-pôles par changement d'échelle et ne requiert pas la simulation de toute la structure. Cette caractéristique fait de la SCT un outil de conception et d'optimisation très puissant. Des structures planaires uniformes et non uniformes excité par un cornet ont étés modélisés avec succès, avec des temps de calcul délais intéressants, employant les ressources normales de l'ordinateur. / Large sized planar structures are increasingly being employed in satellite and radar applications. Two major kinds of such structures i.e. FSS and Reflectarrays are particularly the hottest domains of RF design. But due to their large electrical size and complex cellular patterns, full-wave analysis of these structures require enormous amount of memory and processing requirements. Therefore conventional techniques based on linear meshing either fail to simulate such structures or require resources not available to a common antenna designer. An indigenous technique called Scale-changing Technique addresses this problem by partitioning the cellular array geometry in numerous nested domains defined at different scale-levels in the array plane. Multi-modal networks, called Scale-changing Networks (SCN), are then computed to model the electromagnetic interaction between any two successive partitions by Method of Moments based integral equation technique. The cascade of these networks allows the computation of the equivalent surface impedance matrix of the complete array which in turn can be utilized to compute far-field scattering patterns. Since the computation of scale-changing networks is mutually independent, execution times can be reduced significantly by using multiple processing units. Moreover any single change in the cellular geometry would require the recalculation of only two SCNs and not the entire structure. This feature makes the SCT a very powerful design and optimization tool. Full-wave analysis of both uniform and nonuniform planar structures has successfully been performed under horn antenna excitation in reasonable amount of time employing normal PC resources.

[pt] Esta dissertação investiga o uso das estruturas planares extraídas de imagens RGB-Dem aplicações de Realidade Aumentada. Ter o modelo da cena é fundamental para as aplicações de realidade aumentada. O uso de imagens RGB-D auxilia bastante o processo da construção destes modelos, pois elas fornecem a geometria e os aspectos fotométricos da cena. Devido a grande parte das aplicações de realidade aumentada utilizarem superfícies planares como sua principal componente para projeção de objetos virtuais, é fundamental ter um método robusto e eficaz para obter e representar as estruturas que constituem estas superfícies planares. Neste trabalho, apresentaremos um método para identificar, segmentar e representar estruturas planares a partir de imagens RGB-D. Nossa representação das estruturas planares são polígonos bidimensionais triangulados, simplificados e texturizados, que estão no sistema de coordenadas do plano, onde os pontos destes polígonos definem as regiões deste plano. Demonstramos através de diversos experimentos e da implementação de uma aplicação de realidade aumentada, as técnicas e métodos utilizados para extrair as estruturas planares a partir das imagens RGB-D. / [en] This dissertation investigates the use of planar geometric structures extracted from RGB-D images in Augmented Reality Applications. The model of a scene is essential for augmented reality applications. RGB-D images can greatly help the construction of these models because they provide geometric and photometric information about the scene. Planar structures are prevalent in many 3D scenes and, for this reason, augmented reality applications use planar surfaces as one of the main components for projection of virtual objects. Therefore, it is extremely important to have robust and efficient methods to acquire and represent the structures that compose these planar surfaces. In this work, we will present a method for identifying, targeting and representing planar structures from RGB-D images. Our planar structures representation is triangulated two-dimensional polygons, simplified and textured, forming a triangle mesh intrinsic to the plane that defines regions in this space corresponding to surface of objects in the 3D scene. We have demonstrated through various experiments and implementation of an augmented reality application, the techniques and methods used to extract the planar structures from the RGB-D images.

Made available in DSpace on 2014-12-17T14:56:12Z (GMT). No. of bitstreams: 1 PedroIAN_DISSERT.pdf: 1986241 bytes, checksum: 386b7b9f50f9765c6f2575f4e58ea4e5 (MD5) Previous issue date: 2012-12-11 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Due to major progress of communication system in the last decades, need for more precise characterization of used components. The S-parameters modeling has been used to characterization, simulation and test of communication system. However, limitation of S-parameters to model nonlinear system has created new modeling systems that include the nonlinear characteristics. The polyharmonic distortion modeling is a characterizationg technique for nonlinear systems that has been growing up due to praticity and similarity with S-parameters. This work presents analysis the polyharmonic distortion modeling, the test bench development for simulation of planar structure and planar structure characterization with X-parameters / O grande desenvolvimento dos sistemas de comunica??o nas ?ltimas d?cadas trouxe a necessidade de uma caracteriza??o cada vez mais precisa dos componentes utilizados. A modelagem por meio de par?metros-S ? utilizada para caracteriza??o, simula??o e testes de sistemas de comunica??o desde meados dos anos 60. Contudo a limita??o dos par?metros-S para sistemas lineares fez crescer a necessidade por novos tipos de parametriza??es que incluam as caracter?sticas de sistemas n?o lineares. A modelagem por distor??o poli-harm?nica ? uma t?cnica de caracteriza??o aplicada a sistemas n?o lineares que vem ganhando espa?o na literatura por sua praticidade e semelhan?a conceitual com os par?metros-S. Este trabalho apresentar? uma an?lise da modelagem por distor??o harm?nica, o desenvolvimento de um banco de testes para simula??o de estruturas planares e a caracteriza??o destas estruturas por meio de par?metros-X. Com isso pretende-se analisar a utiliza??o, precis?o e efici?ncia da modelagem por distor??o poli-harm?nica para estruturas planares