Depth-Based Image Rendering (DIBR) is a popular method to generate 3D virtual image at different view positions using an image and a depth map. In general, DIBR consists of two major operations: image warping and hole filling. Image warping calculates the disparity from the depth map given some information of viewers and display screen. Hole filling is to calculate the color of pixel locations that do not correspond to any pixels in the original image after image warping. Although there are many different hole filling methods that determine the colors of the blank pixels, some undesirable artifacts are still observed in the synthesized virtual image. In this thesis, we present an approach that examines the geometry information near the region of blank pixels in order to reduce the artifacts near the edges of objects. Experimental results show that the proposed design can generate more natural shape around the edges of objects at the cost of more hardware and computation time.

abstract: Blur is an important attribute in the study and modeling of the human visual system. In this work, 3D blur discrimination experiments are conducted to measure the just noticeable additional blur required to differentiate a target blur from the reference blur level. The past studies on blur discrimination have measured the sensitivity of the human visual system to blur using 2D test patterns. In this dissertation, subjective tests are performed to measure blur discrimination thresholds using stereoscopic 3D test patterns. The results of this study indicate that, in the symmetric stereo viewing case, binocular disparity does not affect the blur discrimination thresholds for the selected 3D test patterns. In the asymmetric viewing case, the blur discrimination thresholds decreased and the decrease in threshold values is found to be dominated by the eye observing the higher blur. The second part of the dissertation focuses on texture granularity in the context of 2D images. A texture granularity database referred to as GranTEX, consisting of textures with varying granularity levels is constructed. A subjective study is conducted to measure the perceived granularity level of textures present in the GranTEX database. An objective index that automatically measures the perceived granularity level of textures is also presented. It is shown that the proposed granularity metric correlates well with the subjective granularity scores and outperforms the other methods presented in the literature. A subjective study is conducted to assess the effect of compression on textures with varying degrees of granularity. A logarithmic function model is proposed as a fit to the subjective test data. It is demonstrated that the proposed model can be used for rate-distortion control by allowing the automatic selection of the needed compression ratio for a target visual quality. The proposed model can also be used for visual quality assessment by providing a measure of the visual quality for a target compression ratio. The effect of texture granularity on the quality of synthesized textures is studied. A subjective study is presented to assess the quality of synthesized textures with varying levels of texture granularity using different types of texture synthesis methods. This work also proposes a reduced-reference visual quality index referred to as delta texture granularity index for assessing the visual quality of synthesized textures. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2015

Este trabalho aborda a utilização de tecnologias para a criação de ambientes virtuais baseados em imagens, com uma aplicação na praça central da cidade de Pelotas/RS. Possibilita que o usuário realize interativamente um passeio no entorno da praça com recursos que permitem avaliações arquitetônicas e urbanísticas por meio de simulações de troca de cor nos prédios, inserção de novas construções e análise do estado de conservação de imóveis, com vantagens sobre métodos tradicionais de análises em montagens fotográficas estáticas. Enfatiza a pesquisa de soluções para visualização interativa de ambientes, focado na identificação de fontes de informação e não na sua modelagem matemática. Para a apresentação do trabalho, além da seleção das cenas urbanas que seriam estudadas, foram consideradas técnicas para a modelagem dos elementos arquitetônicos de forma que se obtivesse a máxima preservação das características naturais (estado de conservação, cores e riqueza de detalhes), formas para a visualização destes dados de maneira integrada com dados bibliográficos (histórico, técnicas construtivas e localização) e também a utilização de objetos multimídia para o enriquecimento na apresentação de conteúdos. Na busca de soluções, foram investigadas as técnicas de modelagem fotogramétrica como forma de obtenção de objetos realísticos com a manutenção das características do objeto original em modelos geométricos simplificados. Foram feitos estudos sobre as formas de apresentação de ambientes virtuais navegáveis através de panoramas interativos e também foi estudada uma forma de aproximar a visualização dos conteúdos com a visão natural humana, através da estereoscopia. O trabalho culmina com a fusão de todas as tecnologias estudadas em uma aplicação denominada “Praça República Virtual – PRV” (para resgatar o antigo nome da atual Praça Coronel Pedro Osório), que funciona como um canteiro de provas na medida que abre um leque de opções para utilização em estudos na área de Arquitetura e Urbanismo. / This work approaches the uses of technologies for creation of virtual environments based on images, with an application to the central square of the city of Pelotas/RS. It makes possible to the user to accomplish an interactive walkthrough with resources that allows architectural and urban planning evaluations through simulations of color changes in the buildings, insertion of new constructions and analysis of the conservation condition of the buildings, with advantages if compared to traditional methods of analysis with static photographic assemblies. It emphasizes the research of solutions for interactive visualization of environments, focused in the identification of sources of information and not in mathematical modeling. Besides the selection of the urban scenes to be studied, it was considered techniques for modeling the architectural elements to obtain the maximal preservation of their natural characteristics (conservation state, colors and wealth of details), ways of visualization of nowadays conservation, but integrated with bibliographical dates (historical, constructive techniques and location). It also includes the uses of multimedia objects to the presentation of contents. In the search of solutions, techniques of photogrammetric modeling were investigated, looking for the construction of realistic objects and maintenance of the characteristics of the original object but using simplified geometric models. It was done a search about forms of presentation of navigable virtual environments through interactive panoramas and also using a prototype of stereoscopy. The work culminates with the coalition of all studied technologies in a prototype of the central square of Pelotas called “Praça República Virtual–PRV” (to rescue the old name of the current Square Cel. Pedro Osório). It works like a stonemason of proofs in the measure that opens various options of use in studies in the area of Architecture and Urban Planning.

Este trabalho aborda a utilização de tecnologias para a criação de ambientes virtuais baseados em imagens, com uma aplicação na praça central da cidade de Pelotas/RS. Possibilita que o usuário realize interativamente um passeio no entorno da praça com recursos que permitem avaliações arquitetônicas e urbanísticas por meio de simulações de troca de cor nos prédios, inserção de novas construções e análise do estado de conservação de imóveis, com vantagens sobre métodos tradicionais de análises em montagens fotográficas estáticas. Enfatiza a pesquisa de soluções para visualização interativa de ambientes, focado na identificação de fontes de informação e não na sua modelagem matemática. Para a apresentação do trabalho, além da seleção das cenas urbanas que seriam estudadas, foram consideradas técnicas para a modelagem dos elementos arquitetônicos de forma que se obtivesse a máxima preservação das características naturais (estado de conservação, cores e riqueza de detalhes), formas para a visualização destes dados de maneira integrada com dados bibliográficos (histórico, técnicas construtivas e localização) e também a utilização de objetos multimídia para o enriquecimento na apresentação de conteúdos. Na busca de soluções, foram investigadas as técnicas de modelagem fotogramétrica como forma de obtenção de objetos realísticos com a manutenção das características do objeto original em modelos geométricos simplificados. Foram feitos estudos sobre as formas de apresentação de ambientes virtuais navegáveis através de panoramas interativos e também foi estudada uma forma de aproximar a visualização dos conteúdos com a visão natural humana, através da estereoscopia. O trabalho culmina com a fusão de todas as tecnologias estudadas em uma aplicação denominada “Praça República Virtual – PRV” (para resgatar o antigo nome da atual Praça Coronel Pedro Osório), que funciona como um canteiro de provas na medida que abre um leque de opções para utilização em estudos na área de Arquitetura e Urbanismo. / This work approaches the uses of technologies for creation of virtual environments based on images, with an application to the central square of the city of Pelotas/RS. It makes possible to the user to accomplish an interactive walkthrough with resources that allows architectural and urban planning evaluations through simulations of color changes in the buildings, insertion of new constructions and analysis of the conservation condition of the buildings, with advantages if compared to traditional methods of analysis with static photographic assemblies. It emphasizes the research of solutions for interactive visualization of environments, focused in the identification of sources of information and not in mathematical modeling. Besides the selection of the urban scenes to be studied, it was considered techniques for modeling the architectural elements to obtain the maximal preservation of their natural characteristics (conservation state, colors and wealth of details), ways of visualization of nowadays conservation, but integrated with bibliographical dates (historical, constructive techniques and location). It also includes the uses of multimedia objects to the presentation of contents. In the search of solutions, techniques of photogrammetric modeling were investigated, looking for the construction of realistic objects and maintenance of the characteristics of the original object but using simplified geometric models. It was done a search about forms of presentation of navigable virtual environments through interactive panoramas and also using a prototype of stereoscopy. The work culminates with the coalition of all studied technologies in a prototype of the central square of Pelotas called “Praça República Virtual–PRV” (to rescue the old name of the current Square Cel. Pedro Osório). It works like a stonemason of proofs in the measure that opens various options of use in studies in the area of Architecture and Urban Planning.

Este trabalho aborda a utilização de tecnologias para a criação de ambientes virtuais baseados em imagens, com uma aplicação na praça central da cidade de Pelotas/RS. Possibilita que o usuário realize interativamente um passeio no entorno da praça com recursos que permitem avaliações arquitetônicas e urbanísticas por meio de simulações de troca de cor nos prédios, inserção de novas construções e análise do estado de conservação de imóveis, com vantagens sobre métodos tradicionais de análises em montagens fotográficas estáticas. Enfatiza a pesquisa de soluções para visualização interativa de ambientes, focado na identificação de fontes de informação e não na sua modelagem matemática. Para a apresentação do trabalho, além da seleção das cenas urbanas que seriam estudadas, foram consideradas técnicas para a modelagem dos elementos arquitetônicos de forma que se obtivesse a máxima preservação das características naturais (estado de conservação, cores e riqueza de detalhes), formas para a visualização destes dados de maneira integrada com dados bibliográficos (histórico, técnicas construtivas e localização) e também a utilização de objetos multimídia para o enriquecimento na apresentação de conteúdos. Na busca de soluções, foram investigadas as técnicas de modelagem fotogramétrica como forma de obtenção de objetos realísticos com a manutenção das características do objeto original em modelos geométricos simplificados. Foram feitos estudos sobre as formas de apresentação de ambientes virtuais navegáveis através de panoramas interativos e também foi estudada uma forma de aproximar a visualização dos conteúdos com a visão natural humana, através da estereoscopia. O trabalho culmina com a fusão de todas as tecnologias estudadas em uma aplicação denominada “Praça República Virtual – PRV” (para resgatar o antigo nome da atual Praça Coronel Pedro Osório), que funciona como um canteiro de provas na medida que abre um leque de opções para utilização em estudos na área de Arquitetura e Urbanismo. / This work approaches the uses of technologies for creation of virtual environments based on images, with an application to the central square of the city of Pelotas/RS. It makes possible to the user to accomplish an interactive walkthrough with resources that allows architectural and urban planning evaluations through simulations of color changes in the buildings, insertion of new constructions and analysis of the conservation condition of the buildings, with advantages if compared to traditional methods of analysis with static photographic assemblies. It emphasizes the research of solutions for interactive visualization of environments, focused in the identification of sources of information and not in mathematical modeling. Besides the selection of the urban scenes to be studied, it was considered techniques for modeling the architectural elements to obtain the maximal preservation of their natural characteristics (conservation state, colors and wealth of details), ways of visualization of nowadays conservation, but integrated with bibliographical dates (historical, constructive techniques and location). It also includes the uses of multimedia objects to the presentation of contents. In the search of solutions, techniques of photogrammetric modeling were investigated, looking for the construction of realistic objects and maintenance of the characteristics of the original object but using simplified geometric models. It was done a search about forms of presentation of navigable virtual environments through interactive panoramas and also using a prototype of stereoscopy. The work culminates with the coalition of all studied technologies in a prototype of the central square of Pelotas called “Praça República Virtual–PRV” (to rescue the old name of the current Square Cel. Pedro Osório). It works like a stonemason of proofs in the measure that opens various options of use in studies in the area of Architecture and Urban Planning.

In the past decade, camera manufacturers have offered smaller form factors, smaller pixel sizes (leading to higher resolution images), and faster processing chips to increase the performance of consumer cameras. However, these conventional approaches have failed to capitalize on the spatio-temporal redundancy inherent in images, nor have they adequately provided a solution for finding $3$D point correspondences for cameras sampling different bands of the visible spectrum. In this thesis, we pose the following question---given the repetitious nature of image patches, and appropriate camera architectures, can statistical models be used to increase temporal, structural, or spectral resolution? While many techniques have been suggested to tackle individual aspects of this question, the proposed solutions either require prohibitively expensive hardware modifications and/or require overly simplistic assumptions about the geometry of the scene. We propose a two-stage solution to facilitate image reconstruction; 1) design a linear camera system that optically encodes scene information and 2) recover full scene information using prior models learned from statistics of natural images. By leveraging the tendency of small regions to repeat throughout an image or video, we are able to learn prior models from patches pulled from exemplar images. The quality of this approach will be demonstrated for two application domains, using low-speed video cameras for high-speed video acquisition and multi-spectral fusion using an array of cameras. We also investigate a conventional approach for finding 3D correspondence that enables a generalized assorted array of cameras to operate in multiple modalities, including multi-spectral, high dynamic range, and polarization imaging of dynamic scenes.