As técnicas para síntese de textura em Computação Gráfica constituem um grupo bem específico cujo objetivo principal é a inclusão, na imagem, de alguma informação visual que aumente a percepção de realismo. São identificadas técnicas para síntese de textura com características favoráveis a implementação num ambiente limitado cujo aspecto central é a placa de vídeo VGA, a saber: mapeamento de textura, "bump mapping" e textura sólida. Um sistema para visualização de objetos simples com aplicação das técnicas selecionadas é descrito e implementado. Várias imagens são sintetizadas e os resultados analisados considerando-se o nível de realismo atingido. É explorado o uso de padrões para incremento da resolução visual das imagens em conjunto com a técnica de mapeamento de textura. Apresenta-se uma série de definições para textura das áreas de Computação Gráfica, Psicologia e Processamento de Imagens. Estas definições se integram e possibilitam a formação de um conceito genérico sobre o assunto. Os modelos e técnicas para descrição e síntese de texturas são apresentados, identificando-se as tendências nesta área. / The Computer Graphics texture synthesis techniques are a well defined group which main goal is to add visual information to the image. This visual information will increase the realism. Texture synthesis techniques for implementation in a limited environment are identified, namely texture mapping, bump mapping and solid texture. The main aspect of the environment is the VGA video card. A system is described and implemented to visualize simple objects where the selected texture synthesis techniques were applied . Some images are synthesized and the results are analysed. It is explored the use of patterns to increase images visual resolution in conection with texture mapping technique. It is presented a set of texture definitions from Computer Graphics, Psychology and Image Processing studies. These definitions are integrated and make possible to form a generic concept about the subject. Models and techniques for texture description and synthesis are presented. This survey identified trends in this area.

As técnicas para síntese de textura em Computação Gráfica constituem um grupo bem específico cujo objetivo principal é a inclusão, na imagem, de alguma informação visual que aumente a percepção de realismo. São identificadas técnicas para síntese de textura com características favoráveis a implementação num ambiente limitado cujo aspecto central é a placa de vídeo VGA, a saber: mapeamento de textura, "bump mapping" e textura sólida. Um sistema para visualização de objetos simples com aplicação das técnicas selecionadas é descrito e implementado. Várias imagens são sintetizadas e os resultados analisados considerando-se o nível de realismo atingido. É explorado o uso de padrões para incremento da resolução visual das imagens em conjunto com a técnica de mapeamento de textura. Apresenta-se uma série de definições para textura das áreas de Computação Gráfica, Psicologia e Processamento de Imagens. Estas definições se integram e possibilitam a formação de um conceito genérico sobre o assunto. Os modelos e técnicas para descrição e síntese de texturas são apresentados, identificando-se as tendências nesta área. / The Computer Graphics texture synthesis techniques are a well defined group which main goal is to add visual information to the image. This visual information will increase the realism. Texture synthesis techniques for implementation in a limited environment are identified, namely texture mapping, bump mapping and solid texture. The main aspect of the environment is the VGA video card. A system is described and implemented to visualize simple objects where the selected texture synthesis techniques were applied . Some images are synthesized and the results are analysed. It is explored the use of patterns to increase images visual resolution in conection with texture mapping technique. It is presented a set of texture definitions from Computer Graphics, Psychology and Image Processing studies. These definitions are integrated and make possible to form a generic concept about the subject. Models and techniques for texture description and synthesis are presented. This survey identified trends in this area.

As técnicas para síntese de textura em Computação Gráfica constituem um grupo bem específico cujo objetivo principal é a inclusão, na imagem, de alguma informação visual que aumente a percepção de realismo. São identificadas técnicas para síntese de textura com características favoráveis a implementação num ambiente limitado cujo aspecto central é a placa de vídeo VGA, a saber: mapeamento de textura, "bump mapping" e textura sólida. Um sistema para visualização de objetos simples com aplicação das técnicas selecionadas é descrito e implementado. Várias imagens são sintetizadas e os resultados analisados considerando-se o nível de realismo atingido. É explorado o uso de padrões para incremento da resolução visual das imagens em conjunto com a técnica de mapeamento de textura. Apresenta-se uma série de definições para textura das áreas de Computação Gráfica, Psicologia e Processamento de Imagens. Estas definições se integram e possibilitam a formação de um conceito genérico sobre o assunto. Os modelos e técnicas para descrição e síntese de texturas são apresentados, identificando-se as tendências nesta área. / The Computer Graphics texture synthesis techniques are a well defined group which main goal is to add visual information to the image. This visual information will increase the realism. Texture synthesis techniques for implementation in a limited environment are identified, namely texture mapping, bump mapping and solid texture. The main aspect of the environment is the VGA video card. A system is described and implemented to visualize simple objects where the selected texture synthesis techniques were applied . Some images are synthesized and the results are analysed. It is explored the use of patterns to increase images visual resolution in conection with texture mapping technique. It is presented a set of texture definitions from Computer Graphics, Psychology and Image Processing studies. These definitions are integrated and make possible to form a generic concept about the subject. Models and techniques for texture description and synthesis are presented. This survey identified trends in this area.

In this master's thesis I'm engaged in problematic of texture mapping in ray tracing. Ray tracing is shortly described in the beginning. Texture mapping methods are described then, solid textures first and 2D textures follow. Implementation of MIP map method is deeply described in next chapters. The results are evaluated at the end.

This thesis deals with the synthesis of anisotropic volumetric textures from a single 2D observation. We present variants of non parametric and multi-scale algorithms. Their main specificity lies in the fact that the 3D synthesis process relies on the sampling of a single 2D input sample, ensuring consistency in the different views of the 3D texture. Two types of approaches are investigated, both multi-scale and based on markovian hypothesis. The first category brings together a set of algorithms based on fixed-neighbourhood search, adapted from existing algorithms of texture synthesis from multiple 2D sources. The principle is that, starting from a random initialisation, the 3D texture is modified, voxel by voxel, in a deterministic manner, ensuring that the grey level local configurations on orthogonal slices containing the voxel are similar to configurations of the input image. The second category points out an original probabilistic approach which aims at reproducing in the textured volume the interactions between pixels learned in the input image. The learning is done by non-parametric Parzen windowing. Optimization is handled voxel by voxel by a deterministic ICM type algorithm. Several variants are proposed regarding the strategies used for the simultaneous handling of the orthogonal slices containing the voxel. These synthesis methods are first implemented on a set of structured textures of varied regularity and anisotropy. A comparative study and a sensitivity analysis are carried out, highlighting the strengths and the weaknesses of the different algorithms. Finally, they are applied to the simulation of volumetric textures of carbon composite materials, on nanometric scale snapshots obtained by transmission electron microscopy. The proposed experimental benchmark allows to evaluate quantitatively and objectively the performances of the different methods.

Ce mémoire traite de synthèse de textures volumiques anisotropes à partir d’une observation 2D unique. Nous présentons différentes variantes d’algorithmes non paramétriques et multi-échelles. Leur principale particularité réside dans le fait que le processus de synthèse 3D s’appuie sur l’échantillonnage d’une seule image 2D d’entrée, en garantissant la cohérence selon les différentes vues de la texture 3D. Deux catégories d’approches sont abordées, toutes deux multi-échelles et basées sur une hypothèse markovienne. La première catégorie regroupe un ensemble d’algorithmes dits de recherche de voisinages fixes, adaptés d’algorithmes existants de synthèses de textures volumiques à partir de sources 2D multiples. Le principe consiste, à partir d’une initialisation aléatoire, à modifier les voxels un par un, de façon déterministe, en s’assurant que les configurations locales de niveaux de gris sur des tranches orthogonales contenant le voxel sont semblables à des configurations présentes sur l’image d’entrée. La deuxième catégorie relève d’une approche probabiliste originale dont l’objectif est de reproduire, sur le volume texturé, les interactions entre pixels estimées sur l’image d’entrée. L’estimation est réalisée de façon non paramétrique par fenêtrage de Parzen. L’optimisation est gérée voxel par voxel, par un algorithme déterministe de type ICM. Différentes variantes sont proposées, relatives aux stratégies de gestion simultanée des tranches orthogonales contenant le voxel. Ces différentes méthodes sont d’abord mises en œuvre pour la synthèse d’un jeu de textures structurées, de régularité et d’anisotropie variées. Une analyse comparée et une étude de sensibilité sont menées, mettant en évidence les atouts et faiblesses des différentes approches. Enfin, elles sont appliquées à la simulation de textures volumiques de matériaux composites carbonés, à partir de clichés obtenus à l’échelle nanométrique par microscopie électronique à transmission. Le schéma expérimental proposé permet d’évaluer quantitativement et de façon objective les performances des différentes méthodes. / This thesis deals with the synthesis of anisotropic volumetric textures from a single 2D observation. We present variants of non parametric and multi-scale algorithms. Their main specificity lies in the fact that the 3D synthesis process relies on the sampling of a single 2D input sample, ensuring consistency in the different views of the 3D texture. Two types of approaches are investigated, both multi-scale and based on markovian hypothesis. The first category brings together a set of algorithms based on fixed-neighbourhood search, adapted from existing algorithms of texture synthesis from multiple 2D sources. The principle is that, starting from a random initialisation, the 3D texture is modified, voxel by voxel, in a deterministic manner, ensuring that the grey level local configurations on orthogonal slices containing the voxel are similar to configurations of the input image. The second category points out an original probabilistic approach which aims at reproducing in the textured volume the interactions between pixels learned in the input image. The learning is done by non-parametric Parzen windowing. Optimization is handled voxel by voxel by a deterministic ICM type algorithm. Several variants are proposed regarding the strategies used for the simultaneous handling of the orthogonal slices containing the voxel. These synthesis methods are first implemented on a set of structured textures of varied regularity and anisotropy. A comparative study and a sensitivity analysis are carried out, highlighting the strengths and the weaknesses of the different algorithms. Finally, they are applied to the simulation of volumetric textures of carbon composite materials, on nanometric scale snapshots obtained by transmission electron microscopy. The proposed experimental benchmark allows to evaluate quantitatively and objectively the performances of the different methods.