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Um sistema de calibração de câmera / A camera calibration systemMarques, Clarissa Codá dos Santos Cavalcanti 05 February 2007 (has links)
A camera calibration procedure corresponds to determine the digital geometric and
optical characteristics of the camera from a known initial data set. This problem can
be divided into three steps: a) acquisition of initial data; b) calibration process itself;
and c) optimization. This work presents the development of a calibration tool based on
a generic architecture for any calibration approach. For this aim, the presented system
allows the personalization of each calibration step. In the proposed tool new calibration
procedures are introduced dynamically, allowing a better integration between the modules
of the system. / Fundação de Amparo a Pesquisa do Estado de Alagoas / Um processo de calibração de câmera consiste no problema de determinar as
características geométricas digitais e ópticas da câmera a partir de um conjunto de dados
iniciais. Este problema pode ser dividido em três etapas: aquisição de dados iniciais,
o processo de calibração em si e otimização. Este trabalho propõe o desenvolvimento
de uma ferramenta de calibração baseada em uma arquitetura genérica para qualquer
processo de calibração. Para este propósito, o sistema apresentado neste trabalho permite
a personalização de cada etapa da calibração. A inclusão de novos métodos de calibração
é realizada de forma dinâmica, permitindo assim maior integração e flexibilidade entre os
módulos do sistema.
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Desenvolvimento e análise de um digitalizador câmera-projetor de alta definição para captura de geometria e fotometriaSilva, Roger Correia Pinheiro 26 August 2011 (has links)
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Previous issue date: 2011-08-26 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Um sistema câmera-projetor é capaz de capturar informação geométrica tridimensional
de objetos e ambientes do mundo real. A captura de geometria em tal sistema baseia-se
na projeção de luz estruturada sobre um objeto através do projetor, e na captura da
cena modulada através da câmera. Com o sistema previamente calibrado, a deformação
da luz projetada causada pelo objeto fornece a informação necessária para reconstruir a
geometria do mesmo por meio de triangulação.
Este trabalho descreve o desenvolvimento de um digitalizador câmera-projetor de alta
definição (com resoluções de até 1920x1080 e 1280x720); são detalhadas as etapas e processos
que conduzem à reconstrução de geometria, como calibração câmera-projetor, calibração de cores, processamento da imagem capturada e triangulação. O digitalizador
desenvolvido utiliza a codificação de luz estruturada (b; s)-BCSL, que emprega a projeção
de uma sequência de faixas verticais coloridas sobre a cena. Este esquema de codificação
flexível oferece um número variado de faixas para projeção: quanto maior o número de
faixas, mais detalhada a geometria capturada.
Um dos objetivos deste trabalho é estimar o número limite de faixas (b,s)-BCSL possível dentro das resoluções atuais de vídeo de alta definição. Este número limite é aquele
que provê reconstrução densa da geometria alvo, e ao mesmo tempo possui baixo nível
de erro. Para avaliar a geometria reconstruída pelo digitalizador para os diversos números
de faixas, é proposto um protocolo para avaliação de erro. O protocolo desenvolvido
utiliza planos como objetos para mensurar a qualidade de reconstrução geométrica. A
partir da nuvem de pontos gerada pelo digitalizador, a equação do plano para a mesma é
estimada por meio de mínimos quadrados. Para um número fixo de faixas, são feitas cinco
digitalizações independentes do plano: cada digitalização leva a uma equação; também é
computado o plano médio, estimado a partir da união das cinco nuvens de pontos. Uma
métrica de distância no espaço projetivo é usada para avaliar a precisão e a acurácia de
cada número de faixas projetados.
Além da avaliação quantitativa, a geometria de vários objetos é apresentada para uma
avaliação qualitativa. Os resultados demonstram que a quantidade de faixas limite para
vídeos de alta resolução permite uma grande densidade de pontos mesmo em superfícies
com alta variação de cores. / A camera-projector system is capable of capturing three-dimensional geometric information
of objects and real-world environments. The capture of geometry in such system
is based on the projection of structured light over an object by the projector, and the
capture of the modulated scene through the camera. With a calibrated system, the deformation
of the projected light caused by the object provides the information needed to
reconstruct its geometry through triangulation.
The present work describes the development of a high definition camera-projector system
(with resolutions up to 1920x1080 and 1280x720). The steps and processes that lead
to the reconstruction of geometry, such as camera-projector calibration, color calibration,
image processing and triangulation, are detailed. The developed scanner uses the
(b; s)-BCSL structured light coding, which employs the projection of a sequence of colored
vertical stripes on the scene. This coding scheme offers a flexible number of stripes for
projection: the higher the number of stripes, more detailed is the captured geometry.
One of the objectives of this work is to estimate the limit number of (b; s)-BCSL
stripes possible within the current resolutions of high definition video. This limit number
is the one that provides dense geometry reconstruction, and at the same has low error. To
evaluate the geometry reconstructed by the scanner for a different number of stripes, we
propose a protocol for error measurement. The developed protocol uses planes as objects
to measure the quality of geometric reconstruction. From the point cloud generated by
the scanner, the equation for the same plane is estimated by least squares. For a fixed
number of stripes, five independent scans are made for the plane: each scan leads to one
equation; the median plane, estimated from the union of the five clouds of points, is also
computed. A distance metric in the projective space is used to evaluate the precision and
the accuracy of each number of projected stripes.
In addition to the quantitative evaluation, the geometry of many objects are presented
for qualitative evaluation. The results show that the limit number of stripes for high
resolution video allows high density of points even on surfaces with high color variation.
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The enigma of appearances: photography of the third dimensionFiveash, Tina Dale, Media Arts, College of Fine Arts, UNSW January 2007 (has links)
The Enigma of Appearances is an examination into the medium of three-dimensional photography, with particular focus on the technique of stereoscopy. Invented in the mid-Victorian era, stereoscopy was an attempt to simulate natural three-dimensional perception via a combination of optics, neurology, and a pair of dissimilar images. Whilst successful in producing a powerful illusion of spatial depth and tangibility, the illusion produced by stereoscopy is anything but ??natural??, when compared to three-dimensional perception observed with the naked eye. Rather, stereoscopic photography creates a strange and unnatural interpretation of three-dimensional reality, devoid of atmosphere, movement and sound, where figures appear frozen in mid-motion, like waxwork models, or embalmed creatures in a museum. However, it is precisely stereoscopic photography??s unique and enigmatic interpretation of three-dimensional reality, which gives it its strength, separating it from being a mere ??realistic?? recording of the natural world. This thesis examines the unique cultural position that stereoscopy has occupied since its invention in 1838, from its early role as a tool for the study of binocular vision, to its phenomenal popularity as a form of mass entertainment in the second half of the 19th century, to its emergence in contemporary fine art practice in the late 20th and 21stt centuries. Additionally, The Enigma of Appearances gives a detailed analysis of the theory of spatial depth perception; it discusses the dichotomy between naturalia versus artificialia in relation to stereoscopic vision; and finally, traces the development of experimental studio practice and research into stereoscopic photography, undertaken for this MFA between 2005 and 2007. The resulting work, Camera Mortuaria (Italian for ??Mortuary Room??), is a powerful and innovative series of anaglyptic portraits, based upon an experimental stereoscopic technique that enables the production of extreme close-up three-dimensional photography. Applying this technique to the reproduction of the human face in three-dimensional form, Camera Mortuaria presents a series of ??photo sculptures??, which hover between reality and illusion, pushing the boundaries of stills photography to the limit, and beyond.
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The enigma of appearances: photography of the third dimensionFiveash, Tina Dale, Media Arts, College of Fine Arts, UNSW January 2007 (has links)
The Enigma of Appearances is an examination into the medium of three-dimensional photography, with particular focus on the technique of stereoscopy. Invented in the mid-Victorian era, stereoscopy was an attempt to simulate natural three-dimensional perception via a combination of optics, neurology, and a pair of dissimilar images. Whilst successful in producing a powerful illusion of spatial depth and tangibility, the illusion produced by stereoscopy is anything but ??natural??, when compared to three-dimensional perception observed with the naked eye. Rather, stereoscopic photography creates a strange and unnatural interpretation of three-dimensional reality, devoid of atmosphere, movement and sound, where figures appear frozen in mid-motion, like waxwork models, or embalmed creatures in a museum. However, it is precisely stereoscopic photography??s unique and enigmatic interpretation of three-dimensional reality, which gives it its strength, separating it from being a mere ??realistic?? recording of the natural world. This thesis examines the unique cultural position that stereoscopy has occupied since its invention in 1838, from its early role as a tool for the study of binocular vision, to its phenomenal popularity as a form of mass entertainment in the second half of the 19th century, to its emergence in contemporary fine art practice in the late 20th and 21stt centuries. Additionally, The Enigma of Appearances gives a detailed analysis of the theory of spatial depth perception; it discusses the dichotomy between naturalia versus artificialia in relation to stereoscopic vision; and finally, traces the development of experimental studio practice and research into stereoscopic photography, undertaken for this MFA between 2005 and 2007. The resulting work, Camera Mortuaria (Italian for ??Mortuary Room??), is a powerful and innovative series of anaglyptic portraits, based upon an experimental stereoscopic technique that enables the production of extreme close-up three-dimensional photography. Applying this technique to the reproduction of the human face in three-dimensional form, Camera Mortuaria presents a series of ??photo sculptures??, which hover between reality and illusion, pushing the boundaries of stills photography to the limit, and beyond.
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