Dissertations / Theses on the topic 'Images 2D - Modèles 3D'
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Baudour, Alexis. "Détection de filaments dans des images 2D et 3D : modélisation, étude mathématique et algorithmes." Phd thesis, Université de Nice Sophia-Antipolis, 2009. http://tel.archives-ouvertes.fr/tel-00507520.
Full textWeibel, Thomas. "Modèles de minimisation d'énergies discrètes pour la cartographie cystoscopique." Phd thesis, Université de Lorraine, 2013. http://tel.archives-ouvertes.fr/tel-00866824.
Full textWeibel, Thomas. "Modèles de minimisation d'énergies discrètes pour la cartographie cystoscopique." Electronic Thesis or Diss., Université de Lorraine, 2013. http://www.theses.fr/2013LORR0070.
Full textThe aim of this thesis is to facilitate bladder cancer diagnosis. The reference clinical examination is cystoscopy, where an endoscope, inserted into the bladder, allows to visually explore the organ's internal walls on a monitor. The main restriction is the small field of view (FOV) of the instrument, which complicates lesion diagnosis, follow-up and treatment traceability.In this thesis, we propose robust and accurate algorithms to create two- and three-dimensional large FOV maps from cystoscopic video-sequences. Based on recent advances in the field of discrete energy minimization, we propose transformation-invariant cost functions, which allow to robustly register image pairs, related by large viewpoint changes, with sub-pixel accuracy. The transformations linking such image pairs, which current state-of-the-art bladder image registration techniques are unable to robustly estimate, are required to construct maps with several overlapping image trajectories. We detect such overlapping trajectories automatically and perform non-linear global map correction. Finally, the proposed energy minimization based map compositing algorithm compensates small texture misalignments and attenuates strong exposure differences. The obtained textured maps are composed by a maximum of information/quality available from the redundant data of the video-sequence. We evaluate the proposed methods both quantitatively and qualitatively on realistic phantom and clinical data sets. The results demonstrate the robustness of the algorithms, and the obtained maps outperform state-of-the-art approaches in registration accuracy and global map coherence
Truong, Michael Vi Nguyen. "2D-3D registration of cardiac images." Thesis, King's College London (University of London), 2014. https://kclpure.kcl.ac.uk/portal/en/theses/2d3d-registration-of-cardiac-images(afef93e6-228c-4bc7-aab0-94f1e1ecf006).html.
Full textJones, Jonathan-Lee. "2D and 3D segmentation of medical images." Thesis, Swansea University, 2015. https://cronfa.swan.ac.uk/Record/cronfa42504.
Full textHuang, Hui. "Efficient reconstruction of 2D images and 3D surfaces." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2821.
Full textHenrichsen, Arne. "3D reconstruction and camera calibration from 2D images." Master's thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/9725.
Full textA 3D reconstruction technique from stereo images is presented that needs minimal intervention from the user. The reconstruction problem consists of three steps, each of which is equivalent to the estimation of a specific geometry group. The first step is the estimation of the epipolar geometry that exists between the stereo image pair, a process involving feature matching in both images. The second step estimates the affine geometry, a process of finding a special plane in projective space by means of vanishing points. Camera calibration forms part of the third step in obtaining the metric geometry, from which it is possible to obtain a 3D model of the scene. The advantage of this system is that the stereo images do not need to be calibrated in order to obtain a reconstruction. Results for both the camera calibration and reconstruction are presented to verify that it is possible to obtain a 3D model directly from features in the images.
Bowden, Nathan Charles. "Camera based texture mapping: 3D applications for 2D images." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2407.
Full textFilali, Ansary Tarik. "Indexation de modèles 3D à partir de vues 2D." Evry, Institut national des télécommunications, 2006. http://www.theses.fr/2006TELE0006.
Full textThe management of big databases of three-dimensional models ( used in CAD applications, visualization, games, etc. ) is very important domain. The ability to characterize and easily retrieve 3D models is a key issue for the designers and the final users. In this frame, two main appoaches exist : search by example of a 3D model, and search by a 2D view or photo. In this thesis we focus ont he characterization of a 3D model by a set of views ( called characteristic views), and on the indexing process of the 3D models using theses characteristic views. In this thesis, we propose a new method for the selection of the " optimal" characteristic views set based on an informational criterion ( Bayesian information criteria). Starting from fact that all the views of a model 3D do not contain the same quantity of information about 3D model, we present a new bayesian approach for the indexing of the 3D models using their views. Our approach takes into account the probability of appreance of a 3D model and the importance of each of its view. Experiments carried on a database of 5000 3D models provided by Renault, within the framework of the RNRT SEMANTIC-D, show the good results of our method on mechanical objects. We compared our method with the most recent and relevant 3D models indexing methods using the standard database " Princeton Shape Benchmark". These experiments highlighted the very good results of our method compared with the ither approaches. To access our results and permit the test of our method, we made 3D search engine available online accessible using a PC or a PDA. Our searche engine permit the search for 3D objects using an example 3D model, a drawing or one or more photographs
Allouch, Yair. "Multi scale geometric segmentation on 2D and 3D Digital Images /." [Beer Sheva] : Ben Gurion University of the Negev, 2007. http://aranne5.lib.ad.bgu.ac.il/others/AlloucheYair.pdf.
Full textDowell, Rachel J. (Rachel Jean). "Registration of 2D ultrasound images in preparation for 3D reconstruction." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10181.
Full textCheng, Yuan 1971. "3D reconstruction from 2D images and applications to cell cytoskeleton." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/88870.
Full textIncludes bibliographical references (leaves 121-129).
Approaches to achieve three dimensional (3D) reconstruction from 2D images can be grouped into two categories: computer-vision-based reconstruction and tomographic reconstruction. By exploring both the differences and connections between these two types of reconstruction, the thesis attempts to develop a new technique that can be applied to 3D reconstruction of biological structures. Specific attention is given to the reconstruction of the cell cytoskeleton from electron microscope images. The thesis is composed of two parts. The first part studies computer-vision-based reconstruction methods that extract 3D information from geometric relationship among images. First, a multiple-feature-based stereo reconstruction algorithm that recovers the 3D structure of an object from two images is presented. A volumetric reconstruction method is then developed by extending the algorithm to multiple images. The method integrates a sequence of 3D reconstruction from different stereo pairs. It achieves a globally optimized reconstruction by evaluating certainty values of each stereo reconstruction. This method is tuned and applied to 3D reconstruction of the cell cytoskeleton. Feasibility, reliability and flexibility of the method are explored.
(cont.) The second part of the thesis focuses on a special tomographic reconstruction, discrete tomography, where the object to be reconstructed is composed of a discrete set of materials each with uniform values. A Bayesian labeling process is proposed as a framework for discrete tomography. The process uses an expectation-maximization (EM) algorithm with which the reconstruction is obtained efficiently. Results demonstrate that the proposed algorithm achieves high reconstruction quality even with a small number of projections. An interesting relationship between discrete tomography and conventional tomography is also derived, showing that discrete tomography is a more generalized form of tomography and conventional tomography is only a special case of such generalization.
by Yuan Cheng.
Ph.D.
Mertzanidou, T. "Automatic correspondence between 2D and 3D images of the breast." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1362435/.
Full textPhan, Tan Binh. "On the 3D hollow organ cartography using 2D endoscopic images." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0135.
Full textStructure from motion (SfM) algorithms represent an efficient means to construct extended 3D surfaces using images of a scene acquired from different viewpoints. SfM methods simultaneously determine the camera motion and a 3D point cloud lying on the surfaces to be recovered. Classical SfM algorithms use feature point detection and matching methods to track homologous points across the image sequences, each point track corresponding to a 3D point to be reconstructed. The SfM algorithms exploit the correspondences between homologous points to recover the 3D scene structure and the successive camera poses in an arbitrary world coordinate system. There exist different state-of-the-art SfM algorithms which can efficiently reconstruct different types of scenes, under the condition that the images include enough textures or structures. However, most of the existing solutions are inappropriate, or at least not optimal, when the sequences of images are without or only with few textures. This thesis proposes two dense optical flow (DOF)-based SfM solutions to reconstruct complex scenes using images with few textures and acquired under changing illumination conditions. It is notably shown how accurate DOF fields can be optimally used due to an image selection strategy which both maximizes the number and size of homologous point sets, and minimizes the errors in the homologous point localization. The accuracy of the proposed 3D cartography methods is assessed on phantoms with known dimensions. The robustness and the interest of the proposed methods are demonstrated on various complex medical scenes using a constant algorithm parameter set. The proposed solutions reconstructed organs seen in different medical examinations (epithelial surface of the inner stomach wall, inner epithelial bladder surface, and the skin surface in dermatology) and various imaging modalities (white light for all examinations, green-blue light in gastroscopy and fluorescence in cystoscopy)
Zhang, Yan. "Feature-based automatic registration of images with 2D and 3D models." Thesis, University of Central Lancashire, 2006. http://clok.uclan.ac.uk/21603/.
Full textMastin, Dana Andrew. "Statistical methods for 2D-3D registration of optical and LIDAR images." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/55123.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 121-123).
Fusion of 3D laser radar (LIDAR) imagery and aerial optical imagery is an efficient method for constructing 3D virtual reality models. One difficult aspect of creating such models is registering the optical image with the LIDAR point cloud, which is a camera pose estimation problem. We propose a novel application of mutual information registration which exploits statistical dependencies in urban scenes, using variables such as LIDAR elevation, LIDAR probability of detection (pdet), and optical luminance. We employ the well known downhill simplex optimization to infer camera pose parameters. Utilization of OpenGL and graphics hardware in the optimization process yields registration times on the order of seconds. Using an initial registration comparable to GPS/INS accuracy, we demonstrate the utility of our algorithms with a collection of urban images. Our analysis begins with three basic methods for measuring mutual information. We demonstrate the utility of the mutual information measures with a series of probing experiments and registration tests. We improve the basic algorithms with a novel application of foliage detection, where the use of only non-foliage points improves registration reliability significantly. Finally, we show how the use of an existing registered optical image can be used in conjunction with foliage detection to achieve even more reliable registration.
by Dana Andrew Mastin.
S.M.
Qiu, Xuchong. "2D and 3D Geometric Attributes Estimation in Images via deep learning." Thesis, Marne-la-vallée, ENPC, 2021. http://www.theses.fr/2021ENPC0005.
Full textThe visual perception of 2D and 3D geometric attributes (e.g. translation, rotation, spatial size and etc.) is important in robotic applications. It helps robotic system build knowledge about its surrounding environment and can serve as the input for down-stream tasks such as motion planning and physical intersection with objects.The main goal of this thesis is to automatically detect positions and poses of interested objects for robotic manipulation tasks. In particular, we are interested in the low-level task of estimating occlusion relationship to discriminate different objects and the high-level tasks of object visual tracking and object pose estimation.The first focus is to track the object of interest with correct locations and sizes in a given video. We first study systematically the tracking framework based on discriminative correlation filter (DCF) and propose to leverage semantics information in two tracking stages: the visual feature encoding stage and the target localization stage. Our experiments demonstrate that the involvement of semantics improves the performance of both localization and size estimation in our DCF-based tracking framework. We also make an analysis for failure cases.The second focus is using object shape information to improve the performance of object 6D pose estimation and do object pose refinement. We propose to estimate the 2D projections of object 3D surface points with deep models to recover object 6D poses. Our results show that the proposed method benefits from the large number of 3D-to-2D point correspondences and achieves better performance. As a second part, we study the constraints of existing object pose refinement methods and develop a pose refinement method for objects in the wild. Our experiments demonstrate that our models trained on either real data or generated synthetic data can refine pose estimates for objects in the wild, even though these objects are not seen during training.The third focus is studying geometric occlusion in single images to better discriminate objects in the scene. We first formalize geometric occlusion definition and propose a method to automatically generate high-quality occlusion annotations. Then we propose a new occlusion relationship formulation (i.e. abbnom) and the corresponding inference method. Experiments on occlusion reasoning benchmarks demonstrate the superiority of the proposed formulation and method. To recover accurate depth discontinuities, we also propose a depth map refinement method and a single-stage monocular depth estimation method.All the methods that we propose leverage on the versatility and power of deep learning. This should facilitate their integration in the visual perception module of modern robotic systems.Besides the above methodological advances, we also made available software (for occlusion and pose estimation) and datasets (of high-quality occlusion information) as a contribution to the scientific community
ARMANDE, NASSER. "Caracterisation de reseaux fins dans les images 2d et 3d applications : images satellites et medicales." Paris 11, 1997. http://www.theses.fr/1997PA112094.
Full textSdiri, Bilel. "2D/3D Endoscopic image enhancement and analysis for video guided surgery." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCD030.
Full textMinimally invasive surgery has made remarkable progress in the last decades and became a very popular diagnosis and treatment tool, especially with the rapid medical and technological advances leading to innovative new tools such as robotic surgical systems and wireless capsule endoscopy. Due to the intrinsic characteristics of the endoscopic environment including dynamic illumination conditions and moist tissues with high reflectance, endoscopic images suffer often from several degradations such as large dark regions,with low contrast and sharpness, and many artifacts such as specular reflections and blur. These challenges together with the introduction of three dimensional(3D) imaging surgical systems have prompted the question of endoscopic images quality, which needs to be enhanced. The latter process aims either to provide the surgeons/doctors with a better visual feedback or improve the outcomes of some subsequent tasks such as features extraction for 3D organ reconstruction and registration. This thesis addresses the problem of endoscopic image quality enhancement by proposing novel enhancement techniques for both two-dimensional (2D) and stereo (i.e. 3D)endoscopic images.In the context of automatic tissue abnormality detection and classification for gastro-intestinal tract disease diagnosis, we proposed a pre-processing enhancement method for 2D endoscopic images and wireless capsule endoscopy improving both local and global contrast. The proposed method expose inner subtle structures and tissues details, which improves the features detection process and the automatic classification rate of neoplastic,non-neoplastic and inflammatory tissues. Inspired by binocular vision attention features of the human visual system, we proposed in another workan adaptive enhancement technique for stereo endoscopic images combining depth and edginess information. The adaptability of the proposed method consists in adjusting the enhancement to both local image activity and depth level within the scene while controlling the interview difference using abinocular perception model. A subjective experiment was conducted to evaluate the performance of the proposed algorithm in terms of visual qualityby both expert and non-expert observers whose scores demonstrated the efficiency of our 3D contrast enhancement technique. In the same scope, we resort in another recent stereo endoscopic image enhancement work to the wavelet domain to target the enhancement towards specific image components using the multiscale representation and the efficient space-frequency localization property. The proposed joint enhancement methods rely on cross-view processing and depth information, for both the wavelet decomposition and the enhancement steps, to exploit the inter-view redundancies together with perceptual human visual system properties related to contrast sensitivity and binocular combination and rivalry. The visual qualityof the processed images and objective assessment metrics demonstrate the efficiency of our joint stereo enhancement in adjusting the image illuminationin both dark and saturated regions and emphasizing local image details such as fine veins and micro vessels, compared to other endoscopic enhancement techniques for 2D and 3D images
Sebbahi, Ali. "Segmentation 2D et 3D par modèles déformables en imagerie cardio-vasculaire." Paris 12, 1995. http://www.theses.fr/1995PA120040.
Full textRandell, Charles James. "3D underwater monocular machine vision from 2D images in an attenuating medium." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ32764.pdf.
Full textLaw, Kwok-wai Albert, and 羅國偉. "3D reconstruction of coronary artery and brain tumor from 2D medical images." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31245572.
Full textZöllei, Lilla 1977. "2D-3D rigid-body registration of X-ray flourscopy and CT images." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86790.
Full textReddy, Serendra. "Automatic 2D-to-3D conversion of single low depth-of-field images." Doctoral thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/24475.
Full textKotronis, Panagiotis. "Cisaillement dynamique de murs en béton armé : modèles simplifiés 2D et 3D." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2000. http://tel.archives-ouvertes.fr/tel-00074469.
Full textChaudhary, Priyanka. "SPHEROID DETECTION IN 2D IMAGES USING CIRCULAR HOUGH TRANSFORM." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_theses/9.
Full textAgerskov, Niels, and Gabriel Carrizo. "Application for Deriving 2D Images from 3D CT Image Data for Research Purposes." Thesis, KTH, Skolan för teknik och hälsa (STH), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-190881.
Full textPå Karolinska universitetssjukhuset, Huddinge har man länge önskat möjligheten att utföra mallningar av höftproteser med hjälp av data från datortomografiundersökningar (DT). Detta har hittills inte varit möjligt eftersom programmet som används för mallning av höftproteser enbart accepterar traditionella slätröntgenbilder. Därför var syftet med detta projekt att skapa en mjukvaru-applikation som kan användas för att generera 2D-bilder för mallning av proteser från DT-data. För att skapa applikationen användes huvudsakligen Python-kodbiblioteken NumPy och The Visualization Toolkit (VTK) tillsammans med användargränssnittsbiblioteket PyQt4. I applikationen ingår ett grafiskt användargränssnitt och metoder för optimering av bilderna i mallningssammanhang. Applikationen fungerar men bildernas kvalitet måste utvärderas med en större urvalsgrupp.
North, Peter R. J. "The reconstruction of visual appearance by combining stereo surfaces." Thesis, University of Sussex, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362837.
Full textMonnier, Fabrice. "Amélioration de la localisation 3D de données laser terrestre à l'aide de cartes 2D ou modèles 3D." Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1114/document.
Full textTechnological advances in computer science (software and hardware) and particularly, GPS localization made digital models accessible to all people. In recent years, mobile mapping systems has enabled large scale mobile 3D scanning. One advantage of this technology for the urban environment is the potential ability to improve existing 2D or 3D database, especially their level of detail and variety of represented objects. Geographic database consist of a set of geometric primitives (generally 2D lines and plans or triangles in 3D) with a coarse level of detail but with the advantage of being available over wide geographical areas. They come from the fusion of various information (old campaigns performed manually, automated or hybrid design) wich may lead to manufacturing errors. The mobile mapping systems can acquire laser point clouds. These point clouds guarantee a fine level of detail up to more than one points per square centimeter. But there are some disavantages :- a large amount of data on small geographic areas that may cause problems for storage and treatment of up to several Terabyte during major acquisition,- the inherent acquisition difficulties to image the environment from the ground. In urban areas, the GPS signal required for proper georeferencing data can be disturbed by multipath or even stopped when GPS masking phenomena related to the reduction of the portion of the visible sky to capture enough satellites to find a good localization. Improve existing databases through these dataset acquired by a mobile mapping system requires alignment of these two sets. The main objective of this manuscript is to establish a pipeline of automatic processes to register these datasets together in the most reliable manner. Co-registration this data can be done in different ways. In this manuscript we have focused our work on the registration of mobile laser point cloud on geographical database by using a drift model suitable for the non rigid drift of these kind of mobile data. We have also developped a method to register geographical database containing semantics on mobile point cloud. The different optimization step performed on our methods allows to register the data fast enough for post-processing pipeline, which allows the management of large volumes of data (billions of laser points and thousands geometric primitives). We have also discussed on the problem of joint deformation. Our methods have been tested on simulated data and real data from different mission performed by IGN
Valette, Sébastien. "Modèles de maillages déformables 2D et multirésolution surfaciques 3D sur une base d'ondelettes." Lyon, INSA, 2002. http://theses.insa-lyon.fr/publication/2002ISAL0002/these.pdf.
Full textThis work aims at providing mesh-based image processing algorithms. The first part introduces a new theoretical support and an algorithm for multiresolution analysis of 3D surface meshes. This approach is a generalization of the wavelet decomposition of surface meshes proposed by Lounsbery, which initial definition can be applied only to regularly subdivided meshes. This extension requires the definition of an irregular subdivision scheme, allowing multiresolution analysis on irregular meshes. The second part handles video objects segmentation and tracking in 2D+t sequences. We propose a new active mesh algorithm that moves the mesh nodes on motion discontinuities. The motion inside each cell is estimated by a competitive back-forward approach. This approach allows nodes displacements without remeshing motion occlusion regions. A spatial constraint allows a better deformation in homogeneous regions. A temporal regularization constraint ensures the tracking consistency. The third part adds a conclusion and possible future work on multiresolution video objects representation, with the algorithm proposed in the first part
Lubniewski, Pawel. "Recalage 3D/2D d'images pour le traitement endovasculaire des dissections aortiques." Thesis, Clermont-Ferrand 1, 2014. http://www.theses.fr/2014CLF1MM24/document.
Full textIn this study, we present our works related to 3D/2D image registrationfor aorti dissition. Its aim is to propose a visualization of medial datawhih an be used by physians during endovas ular proedures.For this purpose, we have proposed a parametrimodel of aorta, alleda Tubular Envelope. It is used to express the global shape and deformationsof the aorta, by a minimal number of parameters. The tubular envelope isused in our image registration algorithms.The registration by ITD (Image Transformation Descriptors) is our ori-ginal method of image alignment : itomputes the rigid 2D transformation between data sets diretly, without any optimization process.We provide thedefinition of this method, as well as the proposition of several descriptors' formulae, in the base of images of aorta. The technique allows us to quickly and a poarse alignment between data. We also propose the extension of theoriginal approach for the registration of 3D and 2D images.The complete chain of 3D/2D image registration techniques, proposedin this document, consists of the ITD stage, followed by an intensity basedhybrid method. The use of our 3D/2D algorithm, based on the image trans-formation descriptors as an initialization phase, reduces the computing timeand improves the efficiency of the presented approach.We have tested our registration methods for the medical images of several patients after endovasular treatment. Results have been approved by our clinical specialists and our approach.We have tested our registration methods for the medical images of several patients after endovascular treatment. Results have been approved by our clinical specialists and our approach may appear in the intervention rooms in the futur
Sintorn, Ida-Maria. "Segmentation methods and shape descriptions in digital images : applications in 2D and 3D microscopy /." Uppsala : Centre for Image Analysis, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/200520.pdf.
Full textBEIL, FRANK MICHAEL. "Approche structurelle de l'analyse de la texture dans les images cellulaires 2d et 3d." Paris 7, 1999. http://www.theses.fr/1999PA077019.
Full textMEZERREG, MOHAMED. "Structures de donnees graphiques : contribution a la conception d'un s.g.b.d. images 2d et 3d." Paris 7, 1990. http://www.theses.fr/1990PA077155.
Full textStebbing, Richard. "Model-based segmentation methods for analysis of 2D and 3D ultrasound images and sequences." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:f0e855ca-5ed9-4e40-994c-9b470d5594bf.
Full textARAÚJO, Caio Fernandes. "Segmentação de imagens 3D utilizando combinação de imagens 2D." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/21040.
Full textMade available in DSpace on 2017-08-30T18:18:42Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertacao Caio Fernandes Araujo Versão Biblioteca.pdf: 4719896 bytes, checksum: 223db1c4382e6f970dc2cd659978ab60 (MD5) Previous issue date: 2016-08-12
CAPES
Segmentar imagens de maneira automática é um grande desafio. Apesar do ser humano conseguir fazer essa distinção, em muitos casos, para um computador essa divisão pode não ser tão trivial. Vários aspectos têm de ser levados em consideração, que podem incluir cor, posição, vizinhanças, textura, entre outros. Esse desafio aumenta quando se passa a utilizar imagens médicas, como as ressonâncias magnéticas, pois essas, além de possuírem diferentes formatos dos órgãos em diferentes pessoas, possuem áreas em que a variação da intensidade dos pixels se mostra bastante sutil entre os vizinhos, o que dificulta a segmentação automática. Além disso, a variação citada não permite que haja um formato pré-definido em vários casos, pois as diferenças internas nos corpos dos pacientes, especialmente os que possuem alguma patologia, podem ser grandes demais para que se haja uma generalização. Mas justamente por esse possuírem esses problemas, são os principais focos dos profissionais que analisam as imagens médicas. Este trabalho visa, portanto, contribuir para a melhoria da segmentação dessas imagens médicas. Para isso, utiliza a ideia do Bagging de gerar diferentes imagens 2D para segmentar a partir de uma única imagem 3D, e conceitos de combinação de classificadores para uni-las, para assim conseguir resultados estatisticamente melhores, se comparados aos métodos populares de segmentação. Para se verificar a eficácia do método proposto, a segmentação das imagens foi feita utilizando quatro técnicas de segmentação diferentes, e seus resultados combinados. As técnicas escolhidas foram: binarização pelo método de Otsu, o K-Means, rede neural SOM e o modelo estatístico GMM. As imagens utilizadas nos experimentos foram imagens reais, de ressonâncias magnéticas do cérebro, e o intuito do trabalho foi segmentar a matéria cinza do cérebro. As imagens foram todas em 3D, e as segmentações foram feitas em fatias 2D da imagem original, que antes passa por uma fase de pré-processamento, onde há a extração do cérebro do crânio. Os resultados obtidos mostram que o método proposto se mostrou bem sucedido, uma vez que, em todas as técnicas utilizadas, houve uma melhoria na taxa de acerto da segmentação, comprovada através do teste estatístico T-Teste. Assim, o trabalho mostra que utilizar os princípios de combinação de classificadores em segmentações de imagens médicas pode apresentar resultados melhores.
Automatic image segmentation is still a great challenge today. Despite the human being able to make this distinction, in most of the cases easily and quickly, to a computer this task may not be that trivial. Several characteristics have to be taken into account by the computer, which may include color, position, neighborhoods, texture, among others. This challenge increases greatly when it comes to using medical images, like the MRI, as these besides producing images of organs with different formats in different people, have regions where the intensity variation of pixels is subtle between neighboring pixels, which complicates even more the automatic segmentation. Furthermore, the above mentioned variation does not allow a pre-defined format in various cases, because the internal differences between patients bodies, especially those with a pathology, may be too large to make a generalization. But specially for having this kind of problem, those people are the main targets of the professionals that analyze medical images. This work, therefore, tries to contribute to the segmentation of medical images. For this, it uses the idea of Bagging to generate different 2D images from a single 3D image, and combination of classifiers to unite them, to achieve statistically significant better results, if compared to popular segmentation methods. To verify the effectiveness of the proposed method, the segmentation of the images is performed using four different segmentation techniques, and their combined results. The chosen techniques are the binarization by the Otsu method, K-Means, the neural network SOM and the statistical model GMM. The images used in the experiments were real MRI of the brain, and the dissertation objective is to segment the gray matter (GM) of the brain. The images are all in 3D, and the segmentations are made using 2D slices of the original image that pass through a preprocessing stage before, where the brain is extracted from the skull. The results show that the proposed method is successful, since, in all the applied techniques, there is an improvement in the accuracy rate, proved by the statistical test T-Test. Thus, the work shows that using the principles of combination of classifiers in medical image segmentation can obtain better results.
Da, Costa Luis Eduardo. "Reconstruction de modèles 3D à partir d'information 2D partielle : application au cas d'une plante." Mémoire, École de technologie supérieure, 2007. http://espace.etsmtl.ca/573/1/DA_COSTA_Luis_Eduardo.pdf.
Full textGrandi, Jerônimo Gustavo. "Multidimensional similarity search for 2D-3D medical data correlation and fusion." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/104133.
Full textImages of the inner anatomy are essential for clinical practice. To establish a correlation between them is an important procedure for diagnosis and treatment. In this thesis, we propose an approach to correlate within-modality 2D and 3D data from ordinary acquisition protocols based solely on the pixel/voxel information. The work was divided into two development phases. First, we explored the similarity problem between medical images using the perspective of image quality assessment. It led to the development of a 2-step technique that settles the compromise between processing speed and precision of two known approaches. We evaluated the quality and applicability of the 2-step and, in the second phase, we extended the method to use similarity analysis to, given an arbitrary slice image (2D), find the location of this slice within the volume data (3D). The solution minimizes the virtually infinite number of possible cross section orientations and uses optimizations to reduce the computational workload and output accurate results. The matching is displayed in a volumetric three-dimensional visualization fusing the 3D with the 2D. An experimental analysis demonstrated that despite the computational complexity of the algorithm, the use of severe data sampling allows achieving a great compromise between performance and accuracy even when performed with low gradient intensity datasets.
Kang, Xin, and 康欣. "Feature-based 2D-3D registration and 3D reconstruction from a limited number of images via statistical inference for image-guidedinterventions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B48079625.
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Orthopaedics and Traumatology
Doctoral
Doctor of Philosophy
Boui, Marouane. "Détection et suivi de personnes par vision omnidirectionnelle : approche 2D et 3D." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLE009/document.
Full textIn this thesis we will handle the problem of 3D people detection and tracking in omnidirectional images sequences, in order to realize applications allowing3D pose estimation, we investigate the problem of 3D people detection and tracking in omnidirectional images sequences. This requires a stable and accurate monitoring of the person in a real environment. In order to achieve this, we will use a catadioptric camera composed of a spherical mirror and a perspective camera. This type of sensor is commonly used in computer vision and robotics. Its main advantage is its wide field of vision, which allows it to acquire a 360-degree view of the scene with a single sensor and in a single image. However, this kind of sensor generally generates significant distortions in the images, not allowing a direct application of the methods conventionally used in perspective vision. Our thesis contains a description of two monitoring approaches that take into account these distortions. These methods show the progress of our work during these three years, allowing us to move from person detection to the 3Destimation of its pose. The first step of this work consisted in setting up a person detection algorithm in the omnidirectional images. We proposed to extend the conventional approach for human detection in perspective image, based on the Gradient-Oriented Histogram (HOG), in order to adjust it to spherical images. Our approach uses the Riemannian varieties to adapt the gradient calculation for omnidirectional images as well as the spherical gradient for spherical images to generate our omnidirectional image descriptor
Chabot, Florian. "Analyse fine 2D/3D de véhicules par réseaux de neurones profonds." Thesis, Université Clermont Auvergne (2017-2020), 2017. http://www.theses.fr/2017CLFAC018/document.
Full textIn this thesis, we are interested in fine-grained analysis of vehicle from an image. We define fine-grained analysis as the following concepts : vehicle detection in the image, vehicle viewpoint (or orientation) estimation, vehicle visibility characterization, vehicle 3D localization and make and model recognition. The design of reliable solutions for fine-grained analysis of vehicle open the door to multiple applications in particular for intelligent transport systems as well as video surveillance systems. In this work, we propose several contributions allowing to address partially or wholly this issue. Proposed approaches are based on joint deep learning technologies and 3D models. In a first section, we deal with make and model classification keeping in mind the difficulty to create training data. In a second section, we investigate a novel method for both vehicle detection and fine-grained viewpoint estimation based on local apparence features and geometric spatial coherence. It uses models learned only on synthetic data. Finally, in a third section, a complete system for fine-grained analysis is proposed. It is based on the multi-task concept. Throughout this report, we provide quantitative and qualitative results. On several aspects related to vehicle fine-grained analysis, this work allowed to outperform state of the art methods
Oudinet, Ghislain. "Analyse d'images et modélisation 2D/3D de la microstructure du combustible MOX." Saint-Etienne, 2003. http://www.theses.fr/2003STET4011.
Full textThe microstructure of the MOX fuel, made with UO2 and PuO2, determines his " in pile " behavior. The french companies CEA and COGEMA are highly interested in its description by image analysis, which is the object of the present work. The segmentation algorithms described here use pictures issued from a microprobe and a SEM, to analyse the plutonium and porosity distribution in the fuel pellets. They are innovating, automated and robust enough to be used with a small data set. They have been successfully tested on different fuels, before and after irradation. Three-dimensional informations have been computed with a genetic algorithm. The obtained 3D object size distributions allowed the modeling of many different industrial and research fuels. 3D reconstruction is accurate and stable, and provides a basis for different studies among which the study of the MOX fuel " in pile " behavior
Pitocchi, Jonathan. "Quantitative assessment of bone quality after total hip replacement through medical images: 2D and 3D approaches." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13023/.
Full textChu, Jiaqi. "Orbital angular momentum encoding/decoding of 2D images for scalable multiview colour displays." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274903.
Full textKhouas, Leila. "Visualisation de champs de vecteurs 2D et 3D par modélisation autorégressive bidimensionnelle d'une texture de type fourrure." Lyon, INSA, 1998. http://www.theses.fr/1998ISAL0081.
Full textIn many areas such as fluid dynamics or medical imaging, the analysis of studied phenomena produces complex data that consists in large vector fields. The vectors represent some characteristic of each point on the field such as: a fluid vorticity, a wind velocity or a motion speed. The visualization of vector fields is not straightforward because they have no natural representation. In this work, we propose to build a new representation of vector fields based on furlike texture. We assume that such a texture provides a natural and intuitive representation of a dense vector field. Our approach consists in the development of a texture model that allows 2D synthesis of furlike texture having a 3D aspect. The model is based on the modeling of the texture autocorrelation function (ACF) and a two dimensional Auto Regressive synthesis (2D AR). This provides a simple and efficient 2D generator of furlike texture with a local control of the main attributes of the texture (orientation and length of filaments). We have experimented the use of this texture model to represent vector fields. We use orientation, length and color attributes of our furlike texture to visualize local orientation and magnitude of a 2D vector field. Results are presented using simulated data and cardiac imaging data. We also show how to visualize 3D vector fields defined over 3D surfaces by a simple and appropriate texture mapping procedure. We have applied this technique for special vector fields that simulate fur appearance on 3D objects. This produces images with quite realistic aspect
Bouchetob, Ahmed Lazhar Fodhil. "Contribution à la modélisation en 2D et 3D du phénomène de discage." Lille 1, 1994. http://www.theses.fr/1994LIL10198.
Full textGroher, Martin [Verfasser], Nassir [Akademischer Betreuer] Navab, and Max A. [Akademischer Betreuer] Viergever. "2D-3D Registration of Vascular Images : Towards 3D-Guided Catheter Interventions / Martin Groher. Gutachter: Max A. Viergever ; Nassir Navab. Betreuer: Nassir Navab." München : Universitätsbibliothek der TU München, 2008. http://d-nb.info/1054351694/34.
Full textLafrance, Frederick. "Vers une plateforme cartographique web 2D/3D - dynamique pour la participation citoyenne." Master's thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/33141.
Full textWeb virtual globes can facilitate communication between urban planners and citizens. Recent studies have shown that 3D rather than 2D representations can be more effective in communicating information. However, such visualization presents several challenges, including the level of detail, realism and abstraction. Citizens' understanding of the impact of the choices they make during urban planning consultations could be improved by exploiting spatiotemporal simulations. Yet, 4D (3D + time) has rarely been integrated to citizen participation platforms. Therefore, the main objective of this research was to develop a web mapping platform combining multidimensional visualizations (2D, 3D, 4D) in an efficient and intuitive way, so that citizens can better assess and understand the issues of the consultation at stake. To achieve this objective, representation guidelines adapted to citizen consultation as well as spatiotemporal simulations were designed. These concepts were then integrated into a 4D web mapping platform featuring the virtual globe Cesium. User testing was done with 21 experienced participants who used a questionnaire integrated into the platform to validate the concepts. The questionnaire contained 5 simulated realistic case scenarios of citizen participation, in which the participants assessed the intuitiveness of the chosen representations as well as the concepts related to this research. Results showed that spatial information shared within citizen consultations can be intuitively represented through a combination of 2D, 3D and 4D dimensions. Moreover, this combination also offers a better understanding of the impacts related to choices made during the consultation. We consider that the platform proposed in this project is a first step toward a more complete tool dedicated to citizen participation. Future works will aim to use the platform in a real context of citizen consultation.
Lohou, Christophe. "Contribution à l'analyse topologique des images : étude d'algorithmes de squelettisation pour images 2D et 3D selon une approche topologie digitale ou topologie discrète." Marne-la-Vallée, 2001. http://www.theses.fr/2001MARN0120.
Full textThis thesis proposes new thinning algorithms for 2D or 3D images according to two approaches using either the digital topology or the discrete topology. In the first part, we recall some fundamental notions of digital topology and several thinning algorithms amongs the well-known ones, which delete simple points. Then, we propose a methodology to produce new thinning algorithms based on the parallel deletion of P-simple points. Such algorithms are conceived in order to they delete at least the points removed by another one given existent thinning algorithm. By applying this methodology, we produce two new algorithms. Although results seem to be satisfying, the proposal and encoding of new proposed algorithms are not easy. In the second part, we use the concept of partially order set (or poset). We propose more straightforwardly than before, a thinning algorithm consisting in the repetition of parallel deletion of αn-simple points, followed by the parallel deletion of βn-simple points. We also have proposed new definitions of end points which permit us to obtain either curve skeletons or surface skeletons. The thinning scheme is used on 2D, 3D binary images, or on 2D grayscale images. At last, a study of a parallel filtering of skeletons is developped
Micheli, Pascal de. "Formulation explicite en tétraèdres linéaires pour la modélisation 2D et 3D de l'UGV." Paris, ENMP, 2009. http://tel.archives-ouvertes.fr/tel-00409570.
Full textThe aim of this work is to present a FE formulation particularly adapted to the simulation of high speed machining at the cutting edge level. The modelling should be able to detect the very local phenomena that could occur, with reasonable computation times. This code is implemented using the FE library CimLib, which offers robust adaptive non-structured remeshers and allows massive parallel computing. This work can be split in two parts. The first one consist in developing, implementing and validating an explicit type formulation, which is not sensitive to volumetric locking and allows using robust adaptive non-structured remeshers. Two formulations have been compared in the field of rapid dynamics: a semi-explicit one with mixed tetrahedral elements and RFB stabilization and an explicit one with modified linear tetrahedral elements. The second part of the work consists in applying the explicit formulation presented above to high speed machining. A thermal solver is implemented and coupled to the mechanical one. 2D micro machining simulations of Ti6Al4V orthogonal cutting are performed. Results are in very good agreement with literature, and important calculation time sparing is observed. The initiation and propagation of the adiabatic shear band in the chip can be analyzed in details. A R-adaptation procedure has been added to the normal remeshing procedure in order to be able to extend those results in 3D. We can then get closer of the real industrial processes, without loosing precision