L'objectif de cette thèse étudie puis d’implémenter une méthode de reconstruction sur la tomographie aux rayons X qui permette de scanner des gros échantillons avec une bonne résolution qui permettrait de scanner l’intérieur d’un cylindre(tomographie locale) et caractériser des matériaux réels. Notre méthode peut être réalisé pour améliorer la quantitative et la qualitative d'image de fantôme. Dans cette thèse, cet méthode est utilisé sue les matériaux cellulaires. Nous avons réalisé des essais in situ en tomographie aux rayons X sur le mousse ERG et les sphères creuses. Un comparaison entre les résultats d’Élément Finis et des essais réels montre le mécanisme d'endommagement de ces matériaux. / The objective of this thesis studies to implement a method of reconstruction of the X-ray tomography that scanner a large samples with good resolution that would scan inside a cylinder (local tomography) and characterize reals materials. Our method can be done to improve the quantitative and qualitative picture of a ghost. In this thesis, this method is used sue the cellular materials. We conducted tests in situ X-ray tomography on the ERG foam and hollow spheres. A comparison between the results of Finite Element and live testing shows the damage mechanism of these materials.

L'acquisition de la profondeur d'une scène en plus de son image est une caractéristique souhaitable pour de nombreuses applications qui dépendent de l'environnement proche. L'état de l'art dans le domaine de l'extraction de profondeur propose de nombreuses méthodes, mais très peu sont réellement adaptées aux systèmes embarqués miniaturisés. Certaines parce qu'elles sont trop encombrantes en raison de leur système optique, d'autres parce qu'elles nécessitent une calibration délicate, ou des méthodes de reconstructions difficilement implantables dans un système embarqué. Dans cette thèse nous nous concentrons sur des méthodes a faible complexité matérielle afin de proposer une solution algorithmique et optique pour réaliser un capteur permettant à la fois d'extraire la profondeur de la scène, de fournir une évaluation de pertinence de cette mesure et de proposer des images focalisées en tout point. Dans ce sens, nous montrons que les algorithmes du type Depth from Focus (DfF) sont les plus adaptés à ces contraintes. Ce procédé consiste à acquérir un cube d'images multi-focus d'une même scène pour différentes distances de focalisation. Les images sont analysées afin d'annoter chacune des zones de la scène d'un indice relatif à sa profondeur estimée. Cet indice est utilisé pour reconstruire une image nette en tout point.Nous avons travaillé sur la notion de netteté afin de proposer des solutions peu complexes, uniquement basées sur des additions et comparaisons, et de fait, facilement adaptables pour un portage sur une architecture matérielle. La solution proposée effectue une analyse bidirectionnelle de contraste local puis combine les meilleures estimations de profondeur en fin de traitement. Elle se décline en trois approches avec une restriction de la complexité de plus en plus forte et ainsi une aptitude de plus en plus marquée pour l'embarqué. Pour chaque méthode, des cartes de profondeurs et de confiances sont établies, ainsi qu'une image totalement focalisée constituée d'éléments issus de l'ensemble du cube multi-focus. Ces approches sont comparées en qualité et en complexité à d'autres méthodes de l'état de l'art de complexité similaire. Une architecture est proposée pour une implantation matérielle de la solution la plus prometteuse. La conception de ces algorithmes soulève le problème de la qualité d'image. Il est en effet primordial d'avoir une évolution remarquable du contraste ainsi qu'une invariance de la scène lors de la capture du cube multi-focus. Un effet très souvent négligé dans ce type d'approche est le zoom parasite provoqué par la lentille responsable de la variation de focus. Ce zoom de focalisation fragilise l'aspect invariance de la scène et provoque l'apparition d'artefacts sur les trois informations Profondeur, Image et Confiance. La recherche d'optiques adaptées au DfF constitue donc un second axe de ces travaux. Nous avons évalué des lentilles liquides industrielles et des lentilles modales expérimentales à cristaux liquides nématiques conçues durant cette thèse. Ces technologies ont été comparées en termes de rapidité, de qualité d'image, d'intensité de zoom de focalisation engendré, de tension d'alimentation et enfin de qualité des cartes de profondeur extraites et des images totalement focalisées reconstruites.La lentille et l'algorithme répondant le mieux à cette problématique DfF embarqué ont ensuite été évalués via le portage sur une plateforme de développement CPU-GPU permettant l'acquisition d'images et de cartes de profondeurs et de confiances en temps réel. / Acquiring the depth of a scene in addition to its image is a desirable feature for many applications which depend on the near environment. The state of the art in the field of depth extraction offers many methods, but very few are well adapted to small embedded systems. Some of them are too cumbersome because of their large optical system. Others might require a delicate calibration or processing methods which are difficult to implement in an embedded system. In this PhD thesis, we focus on methods with low hardware complexity in order to propose algorithms and optical solutions that extract the depth of the scene, provide a relevance evaluation of this measurement and produce all-in-focus images. We show that Depth from Focus (DfF) algorithms are the most adapted to embedded electronics constraints. This method consists in acquiring a cube of multi-focus images of the same scene for different focusing distances. The images are analyzed in order to annotate each zone of the scene with an index relative to its estimated depth. This index is then used to build an all in focus image. We worked on the sharpness criterion in order to propose low complexity solutions, only based on additions and comparisons, easily adaptable on a hardware architecture. The proposed solution uses bidirectional local contrast analysis and then combines the most relevant depth estimations based on detection confidence at the end of treatment. It is declined in three approaches which need less and less processing and thus make them more and more adapted for a final embedded solution. For each method, depth and confidence maps are established, as well as an all-in-focus image composed of elements from the entire multi-focus cube. These approaches are compared in quality and complexity with other state-of-the-art methods which present similar complexity. A hardware implementation of the best solution is proposed. The design of these algorithms raises the problem of image quality. It is indeed essential to have a remarkable contrast evolution as well as a motionless scene during the capture of the multi-focus cube. A very often neglected effect in this type of approach is the parasitic zoom caused by the lens motion during a focus variation. This "focal zoom" weakens the invariance aspect of the scene and causes artifacts on the depth and confidence maps and on the all in focus image. The search for optics adapted to DfF is thus a second line of research in this work. We have evaluated industrial liquid lenses and experimental nematic liquid crystal modal lenses designed during this thesis. These technologies were compared in terms of speed, image quality, generated focal zoom intensity, power supply voltage and finally the quality of extracted depth maps and reconstructed all in focus images. The lens and the algorithm which best suited this embedded DfF issue were then evaluated on a CPU-GPU development platform allowing real time acquisition of depth maps, confidence maps and all in focus images.

Cette thèse porte sur la modélisation morphologique de matériaux cimentaires, et sur l'analyse de leurs propriétés linéaires élastiques. Dans cet objectif, des images 3D, obtenues par micro-tomographie, de matériaux cimentaires (mortier et béton) sont étudiées. Dans un premier temps, l'image de mortier est segmentée afin d'obtenir une image de microstructure réelle pour des calculs en élasticité linéaire. L'image de béton est utilisée, après traitement, pour la détermination des caractéristiques morphologiques du matériau. Un modèle aléatoire de béton est ensuite développé et validé par des données morphologiques. Ce modèle comporte trois phases qui correspondent à la matrice, les granulats et les pores. La phase des granulats est modélisée par implantation sans recouvrement de polyèdres de Poisson. Pour cela, un algorithme de génération vectorielle de polyèdres de Poisson est mis en place et validé par des mesures morphologiques. Enfin, les propriétés linéaires élastiques effectives de la microstructure de mortier et de microstructures simulées sont déterminées par méthode FFT (Fast-Fourier Transform), pour différents contrastes entre le module de Young des granulats et de la matrice. Cette étude des propriétés effectives est complétée par une analyse locale des champs dans la matrice, afin de déterminer l'arrangement spatial entre les zones de concentration de contraintes dans la matrice, et les différentes phases de la microstructure (granulats et pores). Une caractérisation statistique des champs est de plus réalisée, avec notamment le calcul du Volume Élémentaire Représentatif (VER). Une comparaison des propriétés élastiques effectives et locales obtenues d'une part sur une microstructure simulée contenant des polyèdres et d'autre part sur une microstructure contenant des sphères est de plus effectuée. / The goal of this thesis is to develop morphological models of cementitious materials and use these models to study their local and effective response. To this aim, 3D images of cementitious materials (mortar and concrete), obtained by micro-tomography, are studied. First, the mortar image is segmented in order to obtain an image of a real microstructure, to be used for linear elasticity computations. The image of concrete is used, after being processed, to determine various morphological characteristics of the material. A random model of concrete is then developed and validated by means of morphological data. This model is made up of three phases, corresponding to the matrix, aggregates and voids. The aggregates phase is modelled by implantation of Poisson polyhedra without overlap. For this purpose, an algorithm suited to the vector generation of Poisson polyhedra is introduced and validated with morphological measurements. Finally, the effective linear elastic properties of the mortar and other simulated microstructures are estimated with the FFT (Fast-Fourier Transform) method, for various contrasts between the aggregates and matrix' Young moduli. To complete this work, focused on effective properties, an analysis of the local elastic response in the matrix phase is undertaken, in order to determine the spatial arrangement between stress concentration zones in the matrix and the phases of the microstructure (aggregates and voids). Moreover, a statistical fields characterization, in the matrix, is achieved, including the determination of the Representative Volume Element (RVE) size. Furthermore, a comparison between effective and local elastic properties obtained from microstructures containing polyhedra and spheres is carried out.

Orientador: Cesar Renato Foschini / Resumo: Desenvolvimento de uma ortese personalizada para subluxação de ombro por manufatura aditiva a partir de escaneamento corporal. A órtese é um dispositivo aplicado à superfície externa do corpo para: controlar o alinhamento biomecânico, corrigir ou acomodar a deformidade, proteger e suportar uma lesão, auxiliar na reabilitação, reduzir a dor, aumentar a mobilidade e a independência. Nos últimos anos, o desenvolvimento de órteses usando manufatura aditiva tem se incrementado tanto para membros superiores como inferiores devido a sua capacidade de reposicionar o membro de maneira mais precisa e personalizada. Este trabalho teve como objetivo desenvolver uma metodologia para projetar e fabricar uma órtese de subluxação de ombro utilizando escaneamento corporal e manufatura aditiva. O usuário foi submetido ao escaneamento 3D para obtenção do modelo digital sólido em formato 3D, operações elementares espaciais foram aplicadas ao modelo escaneado do usuário para a obtenção da órtese a fim de gerar uma silhueta tridimensional adequada ao ombro/tórax do paciente. Finalmente, a silhueta foi evoluída a órtese pela agregação de espessura, furos e contornos. Uma vez obtida a órtese, foi impressa, ajustada e testada no paciente. Uma primeira versão foi proposta em função do relato do paciente quanto à adaptação do ombro e conforto, e outras duas versões evolutivas foram desenvolvidas e avançaram para outros aspectos importantes como a redução de peso, graus de liberdade nos ombros saudávei... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Development of a custom shoulder orthosis by additive manufacturing from body from body scan. Orthotics is a device applied to the external surface of the body to control biomechanical alignment, correct or accommodate the deformity, protect and support an injury, assist in rehabilitation, reduce pain, increase mobility and independence. In recent years, the development of orthosis using additive manufacturing has been increasing for both upper and lower limbs because of their ability to more accurately and custom reposition the limb. This work aimed to develop a methodology to design and manufacture a shoulder subluxation orthosis using body scanning and additive manufacturing. The user underwent 3D scanning to obtain the solid digital model in 3D format, spatial elemental operations were applied to the user's scanned model to obtain the orthosis to generate a three-dimensional silhouette suitable for the patient's shoulder / chest. Finally, the silhouette was evolved into orthosis by aggregating thickness, holes, and contours. Once the orthosis was obtained, it was printed, adjusted and tested on the patient. A first version was proposed based on the patient's report on shoulder adaptation and comfort, and two other evolutionary versions were developed and advanced to other important aspects such as weight reduction, degrees of freedom in healthy shoulders and comfort gain. In each of the three prototypes, an evaluation questionnaire was applied to the user to improve diffe... (Complete abstract click electronic access below) / Mestre

Indiana University-Purdue University Indianapolis (IUPUI) / An RGBZ synthetic dataset consisting of five object classes in a variety of virtual environments and orientations was combined with a small sample of real-world image data and used to train the Mask R-CNN (MR-CNN) architecture in a variety of configurations. When the MR-CNN architecture was initialized with MS COCO weights and the heads were trained with a mix of synthetic data and real world data, F1 scores improved in four of the five classes: The average maximum F1-score of all classes and all epochs for the networks trained with synthetic data is F1∗ = 0.91, compared to F1 = 0.89 for the networks trained exclusively with real data, and the standard deviation of the maximum mean F1-score for synthetically trained networks is σ∗ = 0.015, compared to σ_F1 = 0.020 for the networks trained exclusively with real F1 data. Various backgrounds in synthetic data were shown to have negligible impact on F1 scores, opening the door to abstract backgrounds and minimizing the need for intensive synthetic data fabrication. When the MR-CNN architecture was initialized with MS COCO weights and depth data was included in the training data, the net- work was shown to rely heavily on the initial convolutional input to feed features into the network, the image depth channel was shown to influence mask generation, and the image color channels were shown to influence object classification. A set of latent variables for a subset of the synthetic datatset was generated with a Variational Autoencoder then analyzed using Principle Component Analysis and Uniform Manifold Projection and Approximation (UMAP). The UMAP analysis showed no meaningful distinction between real-world and synthetic data, and a small bias towards clustering based on image background.

No description available.

Le système perceptif d’un chirurgien doit s’adapter aux contraintes multisensorielles liées à la chirurgie guidée par l’image. Trois expériences sont conçues pour explorer ces contraintes visuelles et haptiques pour l’apprentissage guidé par l’image. Les résultats montrent que les sujets sont plus rapides et plus précis avec une vision directe. La stéréoscopie 3D n’améliore pas les performances des débutants complets. En réalité virtuelle, la variation de la longueur, largeur, position et complexité de l'objet affecte les performances motrices. La force de préhension appliquée sur un système robotique chirurgical dépend de l'expérience de l'utilisateur. En conclusion, le temps et la précision sont importants, mais la précision doit rester une priorité pour un apprenti. L'homogénéité des groupes d'étude est important pour la recherche sur la formation chirurgicale. Les résultats ont un impact direct sur le suivi des compétences individuelles pour les applications guidées par l'image. / Perceptual system of a surgeon must adapt to conditions of multisensorial constrains regard to planning, control, and execution of the image-guided surgical operations. Three experimental setups are designed to explore these visual and haptic constraints in the image-guided training. Results show that subjects are faster and more precise with direct vision compared to image guidance. Stereoscopic 3D viewing does not represent a performance advantage for complete beginners. In virtual reality, variation in object length, width, position, and complexity affect the motor performance. Applied grip force on a surgical robot system depends on the user experience level. In conclusion, both time and precision matter critically, but trainee gets as precise as possible before getting faster should be a priority. Study group homogeneity and background play key role in surgical training research. The findings have direct implications for individual skill monitoring for image-guided applications.

Les propriétés des matériaux cellulaires dépendent de leur architecture et des défauts de coulée. L'architecture se réfère à la forme et la distribution de la phase solide. Les défauts correspondent à la présence et aux distributions des cavités et d'intermétalliques dans la phase solide du fait de la procédure de fabrication. Deux types de matériaux produits de différentes façons sont étudiés dans cette thèse. D'une part, deux mousses ERG de tailles de pores différentes ont été choisies pour étudier l'effet de la présence des intermétalliques sur la plasticité et l'endommagement. Des tests de micro-traction et des expériences de nanoindentation ont été réalisés sur des éprouvettes extraites de la mousse pour déterminer leur comportement micro-élastoplastique de la phase solide. D'autre part, deux structures ayant la même forme et le même motif répétitif, mais différentes épaisseurs d'entretoises et de nœuds ont été produites par fusion sélective par laser pour étudier aussi la plasticité et l'endommagement. Ce travail de thèse visait à développer une procédure de modélisation par éléments finis générique basée sur les images 3D pour prendre en compte l'effet de la porosité locale et la présence des intermétalliques dans le comportement. Les états initiaux des échantillons ont été numérisés en utilisant des méthodes de tomographie "locale" et "stitching" à haute résolution. Les géométries 3D maillées, la porosité locale et les propriétés élastiques-plastiques de chaque élément ont été directement renseignées à partir des images 3D à haute résolution. Les procédures de déformation et de rupture des échantillons ont été illustrées en effectuant des expériences in-situ/ex-situ couplées à une numérisation tomographique à basse résolution. Des modèles éléments finis conformes à l'image 3D ont été développés pour la simulation des essais de traction/compression et montrent que la prise en compte des hétérogénéités locales de microstructure permet de prédire plus finement le comportement mécanique des structures cellulaires, en particulier dans la rupture. L'étude visait également à déterminer la conductivité thermique d'une mousse ERG hautement poreuse en utilisant des calculs par éléments finis basés sur l'image. Les résultats ont été vérifiés en comparant avec la conductivité thermique mesurée à partir des expériences de plaques chauffées. / The properties of cellular materials depend on their architecture and casting defects. The architecture refers to shape and distribution of the solid phase. Defects correspond to the presence and distribution of cavities or intermetallic particles in the solid phase due to the fabrication procedure. Two types of materials produced by different fabricating routes are studied in this manuscript. On the one hand, two ERG foams with different cell sizes were chosen to study the effect of the presence of intermetallic particles on the plasticity and damage. Micro-tensile tests and nanoindentation experiment were also performed on the struts extracted from the foam to determine their micro elastoplastic behaviour. On the other hand, two structures with the same shape and repetitive pattern but different struts and nodes thicknesses were produced by selective laser melting manufacturing route to study the effect of porosity on plasticity and damage. This PhD-work aimed at developing a generic image-based finite element procedure to take into account the effect of the local porosity and the presence of intermetallic particles into the finite element simulations of the cellular materials. The initial state of the samples was pictured by performing high resolution "local" tomography and "stitching" methods. The 3D geometries were meshed and the local porosity and elastic-plastic properties of each element were directly informed according to high-resolution 3D images. The deformation and fracture procedures of the samples were pictured by performing in-situ/ex-situ experiments coupled with low-resolution tomography scanning. 3D image-based finite element models were developed for the simulation of the tension/compression tests. The microstructurally informed FE models better capture the mechanical behaviour of the cellular structures, especially for the prediction of the fracture. The study also aimed at determining the thermal conductivity of a highly porous ERG foam using image-based finite element calculations. The results were verified by comparing with the measured thermal conductivity from guarded hot plates experiments.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-08-07T19:46:16Z No. of bitstreams: 1 IANNA DUARTE KOBAYASHI DE SOUZA - DISSERTAÇÃO PPGCC 2012..PDF: 9922437 bytes, checksum: d5cbecd7f839d5802dab4ed420e1665b (MD5) / Made available in DSpace on 2018-08-07T19:46:16Z (GMT). No. of bitstreams: 1 IANNA DUARTE KOBAYASHI DE SOUZA - DISSERTAÇÃO PPGCC 2012..PDF: 9922437 bytes, checksum: d5cbecd7f839d5802dab4ed420e1665b (MD5) Previous issue date: 2012-02-29 / O crescimento da incidência da doença arterial coronariana, que atinge parte da população mundial, tem intensificado avanços na área da medicina nuclear, como forma de prevenção e de diagnóstico dessa doença. A cintilografia do miocárdio com técnica SPECT (Single Photon Emission Computed Tomography), associada ao eletrocardiograma, permite a avaliação tanto da funcionalidade quanto da perfusão do músculo cardíaco. Este estudo tem como objetivo principal aplicar técnicas de processamento digital de imagens para segmentar e reorientar automaticamente as imagens 3D de pacientes doentes, geradas por uma gamma camera. Os resultados obtidos foram comparados com os resultados produzidos pela técnica manual e comprovaram a eficácia do método automático proposto. / The increase in incidence of coronary artery disease, which affects part of the world population, has intensified advances in nuclear medicine as a means of prevention and diagnosis of this disease. The myocardial scintigraphy technique SPECT (Single Photon Emission Computed Tomography), associated with the electrocardiogram, enables evaluating both function and perfusion of the heart muscle. The main objective of this study is to apply techniques of digital image processing to segment and reorient automatically the 3D images of sick patients, generated by a gamma camera. The results obtained were compared to those ones produced by a manual technique and the effectiveness of the proposed automatic method was confirmed.

Indiana University-Purdue University Indianapolis (IUPUI) / In crime scene investigations it is necessary to capture images of impression evidence such as tire track or shoe impressions. Currently, such evidence is captured by taking two-dimensional (2D) color photographs or making a physical cast of the impression in order to capture the three-dimensional (3D) structure of the information. This project aims to build a digitizing device that scans the impression evidence and generates (i) a high resolution three-dimensional (3D) surface image, and (ii) a co-registered two-dimensional (2D) color image. The method is based on active structured lighting methods in order to extract 3D shape information of a surface. A prototype device was built that uses an assembly of two line laser lights and a high-definition video camera that is moved at a precisely controlled and constant speed along a mechanical actuator rail in order to scan the evidence. A prototype software was also developed which implements the image processing, calibration, and surface depth calculations. The methods developed in this project for extracting the digitized 3D surface shape and 2D color images include (i) a self-contained calibration method that eliminates the need for pre-calibration of the device; (ii) the use of two colored line laser lights projected from two different angles to eliminate problems due to occlusions; and (iii) the extraction of high resolution color image of the impression evidence with minimal distortion.The system results in sub-millimeter accuracy in the depth image and a high resolution color image that is registered with the depth image. The system is particularly suitable for high quality images of long tire track impressions without the need for stitching multiple images.