京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第21206号 / 情博第659号 / 新制||情||114(附属図書館) / 京都大学大学院情報学研究科知能情報学専攻 / (主査)講師 延原 章平, 教授 美濃 導彦, 教授 松田 哲也 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

Thermoacoustic instabilities in gas turbine operation arise due to unsteady fluctuations in heat release coupled with acoustic oscillations, often caused by varying equivalence ratio perturbations within the flame field. These instabilities can cause irreparable damage to critical turbine components, requiring an understanding of the spatial/temporal variations in equivalence ratio values to predict flame response. The technique of computed tomography for flame chemiluminescence emissions allows for 3D spatially resolved flame measurements to be acquired using a series of integral projections (camera images). High resolution tomography reconstructions require a selection of projection angles around the flame, while captured chemiluminescence of radical species intensity fields can be used to determine local fuel-air ratios. In this work, a tomographic reconstruction algorithm program was developed and utilized to reconstruct the intensity fields of CH* and OH*, and these reconstructions were used to quantify local equivalence ratios in an acoustically forced flame. A known phantom function was used to verify and validate the tomography algorithm, while convergence was determined by subsequent monitoring of selected iterative criteria. A documented method of camera calibration was also reproduced and presented here, with suggestions provided for future calibration improvement. Results are shown to highlight fluctuating equivalence ratio trends while illustrating the effectiveness of the developed tomography technique, providing a firm foundation for future study regarding heat release phenomena. / Master of Science / Acoustic sound amplification occurs in the combustion chamber of a gas turbine due to the machine ramping up in operation. These loud sound oscillations continue to grow larger and can damage the turbine machinery and even threaten the safety of the operator. Because of this, many researchers have attempted to understand and predict this behavior in hopes of ending them altogether. One method of studying these sound amplifications is looking at behaviors in the turbine combustion flame so as to potentially shed light on how these large disturbances form and accumulate. Both heat release rate (the steady release of energy in the form of heat from a combustion flame) and equivalence ratio (the mass ratio of fuel to air burned in a combustion process) have proven viable in illustrating oscillatory flame behavior, and can be visualized using chemiluminescence imaging paired with computed tomography. Chemiluminescence imaging is used to obtain intensity fields of species from high resolution camera imaging, while computed tomography techniques are capable of reconstructing these images into a three-dimensional volume to represent and visualize the combustion flame. These techniques have been shown to function effectively in previous literature and were further implemented in this work. A known calibration technique from previous work was carried out along with reconstructing a defined phantom function to show the functionality of the developed tomography algorithm. Results illustrate the effectiveness of the tomographic reconstruction technique and highlight the amplified acoustic behavior of a combustion flame in a high noise environment.

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Les travaux proposés dans cette thèse s’inscrivent dans le cadre des projets ANR-Cam-Relief et du CPER-CREATIS soutenus par l’Agence Nationale de la Recherche, la région Champagne-Ardenne et le FEDER. Ces études s'inscrivent également dans le cadre d’une collaboration avec la société 3DTV-Solutions et deux groupes du CReSTIC (AUTO et SIC). L’objectif de ce projet est ,entre autre, de concevoir par analogie aux systèmes 2D grands publics actuels, des systèmes de prise de vue 3D permettant de restituer sur écrans reliefs (auto-stéréoscopiques) visibles sans lunettes, des images 3D de qualité. Notre intérêt s’est porté particulièrement sur les systèmes de prise de vue à configuration parallèle et décentrée. Les travaux de recherche menés dans cette thèse sont motivés par l’incapacité des configurations statiques de ces systèmes de prise de vue de capturer correctement des scènes dynamiques réelles pour une restitution autostéréoscopique correcte. Pour surmonter cet obstacle, un schéma d’adaptation de laconfiguration géométrique du système de prise de vue est proposé. Afin de déterminer les paramètres devant être concernés par cette adaptation, une étude de l’effet de la constance de chaque paramètre sur la qualité du rendu relief est menée. Les répercussions des contraintes dynamiques et mécaniques sur le relief restitué sont ensuite examinées. La précision de positionnement des paramètres structurels est abordée à travers la proposition de deux méthodes d’évaluation de la qualité du rendu relief, pour déterminer les seuils d’erreur de positionnement des paramètres structurels du système de prise de vue. Enfin, le problème de la calibration est abordée, où l’on propose une méthode basée sur la méthode de transformation linéaire directe DLT, et des perspectives sont envisagées pour l’asservissement de ces systèmes de prise de vue par asservissement classique ou par asservissement visuel. / The works proposed in this thesis are part of the projects ANR-Cam-Relief and CPER-CREATIS supported by the National Agency of Research, the Champagne-Ardenne region and the FEDER.These studies also join within the framework of a collaboration with the 3DTV-Solutions society and two groups of the CReSTIC (AUTO and SIC).The objective of this project is, among others, to design by analogy to the current 2D popularized systems, 3D shooting systems allowing to display on 3D screens (auto-stereoscopic) visible without glasses, 3D quality images. Our interest has focused particularly on shooting systems with parallel and decentred configuration. There search works led in this thesis are motivated by the inability of the static configurations of these shooting systems to capture correctly real dynamic scenes for a correct auto-stereoscopic endering. To overcome this drawback, an adaptation scheme of the geometrical configuration of the shooting system is proposed. To determine the parameters to be affected by this adaptation,the effect of the constancy of each parameter on the rendering quality is studied. The repercussions of the dynamic and mechanical constraints on the 3D rendering are then examined. Positioning accuracy of the structural parameters is approached through two methods proposed for the rendering quality assessment, to determine the thresholds of positioning error of the structural parameters of the shooting system. Finally, the problem of calibration is discussed where we propose an approach based on the DLT method, and perspectives are envisaged to automatic control of these shooting systems by classical approaches or by visual servoing.

The technology of machine vision is board applied in many aspects such as industrial inspection, medical image processing, remote sensing and nanotechnology. It recovers useful information about a scene from its two-dimension projections. This recovery requires the inversion of a many-to-one mapping. But we usually lose some important data for not exactly correct mapping. It might occur from lens distortion, rotation and perspective distortion, and non-ideal vision systems. Camera calibration can compensate for these ill-conditions. In this thesis I present an active calibration technique derived from Song¡¦s research (1996) for calibrating the camera intrinsic parameters. It requires no reference object and directly uses the images of the environment. We only have to control the camera acting a series translational motion by the XYZ 3-D table.

Cracking is a major pavement distress that jeopardizes road serviceability and traffic safety. Automated pavement distress survey (APDS) systems have been developed using digital imaging technology to replace human surveys for more timely and accurate inspections. Most APDS systems require special lighting devices to illuminate pavements and prevent shadows of roadside objects that distort cracks in the image. Most of the artificial lighting devices are laser based, which are either hazardous to unprotected people, or require dedicated power supplies on the vehicle. This study is aimed to develop a new imaging system that can scan pavement surface at highway speed and determine the severity level of pavement cracking without using any artificial lighting. The new system consists of dual line-scan cameras that are installed side by side to scan the same pavement area as the vehicle moves. Cameras are controlled with different exposure settings so that both sunlit and shadowed areas can be visible in two separate images. The paired images contain complementary details useful for reconstructing an image in which the shadows are eliminated. This paper intends to presents (1) the design of the dual line-scan camera system for a high-speed pavement imaging system that does not require artificial lighting, (2) a new calibration method for line-scan cameras to rectify and register paired images, which does not need mechanical assistance for dynamical scan, (3) a customized image-fusion algorithm that merges the multi-exposure images into one shadow-free image for crack detection, and (4) the results of the field tests on a selected road over a long period. / text

This thesis characterizes the problem of relative camera calibration in the context of three-dimensional volumetric reconstruction. The general effects of camera calibration errors on different parameters of the projection matrix are well understood. In addition, calibration error and Euclidean world errors for a single camera can be related via the inverse perspective projection. However, there has been little analysis of camera calibration for a large number of views and how those errors directly influence the accuracy of recovered three-dimensional models. A specific analysis of how camera calibration error is propagated to reconstruction errors using traditional voxel coloring algorithms is discussed. A review of the Voxel coloring algorithm is included and the general methods applied in the coloring algorithm are related to camera error. In addition, a specific, but common, experimental setup used to acquire real-world objects through voxel coloring is introduced. Methods for relative calibration for this specific setup are discussed as well as a method to measure calibration error. An analysis of effect of these errors on voxel coloring is presented, as well as a discussion concerning the effects of the resulting world-space error.

In this thesis, an innovative algorithm for improving the accuracy of variational space-time stereoscopic reconstruction of ocean surfaces is presented. The space-time reconstruction method, developed based on stereo computer vision principles and variational optimization theory, takes videos captured by synchronized cameras as inputs and produces the shape and superficial pattern of an overlapped region of interest as outputs. These outputs are designed to be the minimizers of the variational optimization framework and are dependent on the estimation of the camera parameters. Therefore, from the perspective of computer vision, the proposed algorithm adjusts the estimation of camera parameters to lower the disagreement between the reconstruction and 2-D camera recordings. From a mathematical perspective, since the minimizers of the variational framework are determined by a set of partial differential equations (PDEs), the algorithm modifies the coefficients of the PDEs based on the current numerical solutions to reduce the minimum of the optimization framework. Our algorithm increases the tolerance to the errors of camera parameters, so the joint operations of our algorithm and the variational reconstruction method can generate accurate space-time models even using videos captured by perturbed cameras as input. This breakthrough prompts the realization of ocean surface reconstruction using videos filmed by remotely-controlled helicopters in the future. A number of techniques, technical or theoretical, are explored to fulfill the development and implementation of the algorithm and relative computation issues. The effectiveness of the proposed algorithm is validated through the statistics applied to real ocean surface reconstructions of data collected from an offshore platform at the Crimean Peninsula, the Black Sea. Moreover, synthetic data generated using computer graphics are customized to simulate various situations that are not recorded in the Crimea dataset for the demonstration of the algorithm.

Made available in DSpace on 2014-06-11T19:22:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-08-25Bitstream added on 2014-06-13T20:48:54Z : No. of bitstreams: 1 espinhosa_drs_me_prud.pdf: 812310 bytes, checksum: 523e8c58d62ab6b4c0194742e34aa362 (MD5) / Em geral, um sistema móvel de mapeamento é caracterizado por um veículo automotor com um par de vídeo-câmaras montado sobre seu teto e sensores de posicionamento e navegação, tais como receptores GPS e sensores inerciais (acelerômetros, giroscópios, hodômetros etc), embarcados no interior do veículo. O processo de mapeamento topográfico e/ou cadastral com base nestes sistemas móveis consiste em capturar imagens das vias de transporte, fazer a determinação da orientação das imagens por meio da combinação de técnicas de posicionamento geodésico e técnicas fotogramétricas, armazenar as imagens georreferenciadas em um banco de imagens e daí extrair feições de interesse e representá-las cartograficamente. Os resultados mostraram que a utilização da injunção da estéreo-base tem influência em aumentar a convergência das câmaras em aproximadamente 0,1º sexagesimal e não melhorou as estimativas das coordenadas dos pontos no espaço objeto em nível de significância de 5%, nem influenciou o cálculo dos parâmetros de orientação interior. Os testes realizados com observações de qualidade pixel e subpixel indicaram que o uso de medidas subpixel é recomendado. Por meio da determinação das diferenças dos ângulos de orientação das imagens, verifica-se que os eixos ópticos não estão realmente paralelos e ortogonais à estéreo-base, há uma pequena convergência (aproximadamente 0,5º sexagesimal) e não estão no mesmo plano (desvio de aproximadamente 0,8º sexagesimal). / In general, a land-based mobile mapping system is featured by a vehicle with a pair of video cameras mounted on its roof and positioning and navigation sensors such as GPS receivers and inertial sensors (accelerometers, gyros, odometers etc) loaded in the vehicle. The topographic and/or cadastral mapping process based on these mobile systems consists on capturing road images, determining the image orientation by geodetic and photogrammetric techniques, saving the georeferenced images in an image database and then extracting and mapping interest features. The results show that the stereo base constraint has influence on to increase camera convergence on 0.1 sexagesimal degree and improves but not significantly, in 5% level, the object point X coordinate estimation, and has minor influence on the interior orientation parameters. The experiments with pixel and subpixel observation indicated that subpixel quality is recommended. Finally, considering the differences of the image orientation angles, it is verified that the optical axes are not truly parallel and orthogonal to the stereo base. In other words, there is a little convergence (0.5 sexagesimal degree) between the optical axes and they are not in the same plain (0.8 sexagesimal degree deviation).

Orientador: João Fernando Custódio da Silva / Banca: Jorge Luís Nunes e Silva Brito / Banca: Aluir Porfírio Dal Poz / Resumo: Em geral, um sistema móvel de mapeamento é caracterizado por um veículo automotor com um par de vídeo-câmaras montado sobre seu teto e sensores de posicionamento e navegação, tais como receptores GPS e sensores inerciais (acelerômetros, giroscópios, hodômetros etc), embarcados no interior do veículo. O processo de mapeamento topográfico e/ou cadastral com base nestes sistemas móveis consiste em capturar imagens das vias de transporte, fazer a determinação da orientação das imagens por meio da combinação de técnicas de posicionamento geodésico e técnicas fotogramétricas, armazenar as imagens georreferenciadas em um banco de imagens e daí extrair feições de interesse e representá-las cartograficamente. Os resultados mostraram que a utilização da injunção da estéreo-base tem influência em aumentar a convergência das câmaras em aproximadamente 0,1º sexagesimal e não melhorou as estimativas das coordenadas dos pontos no espaço objeto em nível de significância de 5%, nem influenciou o cálculo dos parâmetros de orientação interior. Os testes realizados com observações de qualidade pixel e subpixel indicaram que o uso de medidas subpixel é recomendado. Por meio da determinação das diferenças dos ângulos de orientação das imagens, verifica-se que os eixos ópticos não estão realmente paralelos e ortogonais à estéreo-base, há uma pequena convergência (aproximadamente 0,5º sexagesimal) e não estão no mesmo plano (desvio de aproximadamente 0,8º sexagesimal). / Abstract: In general, a land-based mobile mapping system is featured by a vehicle with a pair of video cameras mounted on its roof and positioning and navigation sensors such as GPS receivers and inertial sensors (accelerometers, gyros, odometers etc) loaded in the vehicle. The topographic and/or cadastral mapping process based on these mobile systems consists on capturing road images, determining the image orientation by geodetic and photogrammetric techniques, saving the georeferenced images in an image database and then extracting and mapping interest features. The results show that the stereo base constraint has influence on to increase camera convergence on 0.1 sexagesimal degree and improves but not significantly, in 5% level, the object point X coordinate estimation, and has minor influence on the interior orientation parameters. The experiments with pixel and subpixel observation indicated that subpixel quality is recommended. Finally, considering the differences of the image orientation angles, it is verified that the optical axes are not truly parallel and orthogonal to the stereo base. In other words, there is a little convergence (0.5 sexagesimal degree) between the optical axes and they are not in the same plain (0.8 sexagesimal degree deviation). / Mestre