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本論文は,2台のカメラを独立に動かしながら,人のように時間とともに変形する物体を含む動的シーンを撮影し,その映像からシーンの3次元モデル化を行う方法を提案する.本法は,撮影前のカメラキャリブレーションが不要であり,直ちに対象の撮影を開始できるため,予期せぬイベント・パフォーマンスや突発的な事故など,状況把握の即時性が要求される事象の3次元モデル化が可能である.またカメラを固定しないため,屋外においても撮影が容易である.従って画像伝送機器と組合せれば,遠隔地のシーンの立体モデル化をオンライン処理で行える可能性がある.実験では,屋外において2台の可動カメラで人が運動するシーンを撮影し,その映像をアンテナによる無線伝送で離れた地点にあるコンピュータに送り,そこでシーンの3次元モデル化を行い良好な結果を得た. This paper presents a technique for creating 3-D model of dynamic scenes employing mobile stereo cameras. Since the proposed technique allows independent move of the employed cameras, 3-D modeling of dynamic scenes under various environments such as remote places can be realized. Our technique has an advantage over others in that camera calibration is not prerequisite to the recovery. Therefore, it is possible to model any events that demanded immediacy of situation grasp. In the experiment, a human moving motion captured at a remote place modeled successfully.

Створення моделей для 3-Д моделювання процесу свердління – це складна задача, яка потребує накопичення та аналізу фундаментальних знань з механіки твердого тіла, законів та явищ, що супроводжують процес різання та синтез цих знань в математичному програмному забезпеченні. Одним із таких ПЗ є програмний комплекс LS-Dyna, в основу якого закладений метод кінцевих елементів (МКЕ). В свою чергу використання цього методу ставить ряд викликів перед користувачем зумовлених, передусім, якістю і точністю отриманих результатів. Аналіз публікацій показав, що переважна кількість дослідників, які займаються 3-D моделюванням процесу свердління досліджують залишкові напруження в деталі, отриману стружку, розшарування в композиційних матеріалах, тощо. При такій постановці тіло інструмента розглядається як абсолютно жорстке. Це дозволяє суттєво прискорити час розв’язку задачі, однак унеможливлює визначення напружено-деформованого стану (НДС) різальної частини, та сил різання.

We present an elaborate preconditioning scheme for Krylov subspace methods which has been developed to improve the performance and reduce the execution time of parallel node-based finite-element solvers for three-dimensional electromagnetic numerical modelling in exploration geophysics. This new preconditioner is based on algebraic multigrid that uses different basic relaxation methods, such as Jacobi, symmetric successive over-relaxation and Gauss-Seidel, as smoothers and the wave-front algorithm to create groups, which are used for a coarse-level generation. We have implemented and tested this new preconditioner within our parallel nodal finite-element solver for three-dimensional forward problems in electromagnetic induction geophysics. We have performed series of experiments for several models with different conductivity structures and characteristics to test the performance of our algebraic multigrid preconditioning technique when combined with biconjugate gradient stabilised method. The results have shown that, the more challenging the problem is in terms of conductivity contrasts, ratio between the sizes of grid elements and/or frequency, the more benefit is obtained by using this preconditioner. Compared to other preconditioning schemes, such as diagonal, symmetric successive over-relaxation and truncated approximate inverse, the algebraic multigrid preconditioner greatly improves the convergence of the iterative solver for all tested models. Also, when it comes to cases in which other preconditioners succeed to converge to a desired precision, algebraic multigrid is able to considerably reduce the total execution time of the forward-problem code -up to an order of magnitude. Furthermore, the tests have confirmed that our algebraic multigrid scheme ensures grid-independent rate of convergence, as well as improvement in convergence regardless of how big local mesh refinements are. In addition, algebraic multigrid is designed to be a black-box preconditioner, which makes it easy to use and combine with different iterative methods. Finally, it has proved to be very practical and eficient in the parallel context.

Proton exchange membrane fuel cells (PEMFCs) are very promising for power stationary applications. One of the key components of fuel cells is the flow field plate through which hydrogen fuel will reach the anode and oxygen reach the cathode. Another function of the flow field plate is the electron collection. Traditionally flow field plates are made of graphite which makes them good for current collection. But graphite is costly and the alternative steel is heavy. Thus with development of MEMS technology it becomes important to have flow field plates made of silicon or ceramics. As silicon and ceramics are not good electrical conductors, electrical contacts have to be attached to the Gas Diffusion Layer (GDL) for taking the power to outside world. This is achieved by attaching contact pads to the GDL area which are not covered by flow plates. A reduction in the power output from the cell is observed with current collection from the GDL. Here we build a three dimensional model for a fuel cell in which current collection is carried out by segmented contacts attached to the GDL and the reasons for drop in performance is studied. Also the current collection contact is segmented in order to increase the power output from the cell

This work deals with the passive tracking of the pose of a close-range 3-D modeling device using its own high-rate images in realtime, concurrently with customary 3-D modeling of the scene by laser triangulation. Our former works in Refs. [1,2] successfully implemented visual pose tracking. Accuracy being a central requirement to 3-D modeling, however, here we note that accuracy can be further increased using a graph-based nonlinear optimization of the tracked pose by minimization of reprojection errors. Loop closures e.g. when having scanned all around the objects provide the opportunity to increase pose tracking and 3-D modeling accuracy. The sparse optimization is in the form of a hybrid, keyframe-based bundle adjustment algorithm on stereo keyframes, yielding rapid optimization of the whole trajectory and object mesh model within a second. The optimization is supported by the use of appearance-based SURF descriptors together with a bank of parallel three-point-perspective pose solvers.

This thesis presents the algorithms required for the production of a multisensory hand-held 3-D modeling system, the DLR 3D-Modeler. First, flexible and accurate sensor models, as well as their calibration methods, are presented. Second, the robust and efficient processing of raw sensor data is addressed. Last, the device is extended to passive visual pose tracking, yielding the first hand-held 3-D modeling device for close-range applications that localizes itself passively from its own images in realtime, at a high data rate.

Young patients suffering from Cerebral Palsy are facing difficult choices concerning heavy surgeries. Diagnosis settled by surgeons can be complex and on the other hand decision for patient about getting or not such a surgery involves important reflection effort. Proposed software combining prediction for surgeries and post surgery kinematic values, and from 3D model representing the patient is an innovative tool helpful for both patients and medicine professionals. Beginning with analysis and classification of kinematics values from Data Base extracted from gait analysis in 3 separated clusters, it is possible to determine close similarity between patients. Prediction surgery best adapted to improve a patient gait is then determined by operating a suitable preconditioned neural network. Finally, patient 3D modeling based on kinematic values analysis, is animated thanks to post surgery kinematic vectors characterizing the closest patient selected from patients clustering., {"references":["","V. Quentin: Cerebral Palsy, Saint-Maurice Hospital, 2012","L. R. Smith, H. G. Chambers, S. Subramaniam, R. L. Lieber:\nTranscriptional Abnormalities of Hamstring Muscle\nContractures in Children with Cerebral Palsy, PLoS One,Vol.7(8),\npp.e40686, 2012","K. M. Steele, A. Seth, J. L. Hicks, M. S. Schwartz, S. L. Delp : Muscle\nContributions to Support and Progression During Single-limb Stance in\nCrouch Gait, J. of Biomechanics, Vol.43, pp.2099–2105, 2010; H.\nSadeghi, P. Allard, M. Duhaime: Contributions of Lower-Limb Muscle\nPower in Gait of People Without Impairments, Phys. Ther., Vol.80(12),\npp.1188–1196, 2000","T. Rezgui: Musculoskeletal Modeling of Cerebral Palsy Children, Ph.D.\nThesis, UTC Compiegne, 2012; D.A. Winter : The Biomechanics and\nMotor Control of Human Gait: Normal, Elderly and Pathological,\nUniv. Waterloo Press, Ontario, Canada, 1991","K. N. Kuo, D. W. Hang, P. A. Smith: External Rotation Osteotomy of\nFemur in Patients with Spastic Cerebral Palsy, J. Muskoskeletal Res.,\nVol.2(1), pp.1, 1998","A. M. K. Wong, Chia-Ling Chen, Wei-Hsien Hong, Wen-\nKoChiou, Hsieh-Ching Chen, Fuk-Tan Tang: Gait Analysis through\nFoot Pattern Recognition for Children with Cerebral Palsy, J.\nMuskoskeletal Res., Vol.3(1), pp.71,1999; B. McWilliams, M. Cowley,\nD. Nicholson: Foot Kinematics and Kinetics During Adolescent Gait,\nGait and Posture, Vol.17, pp.214224, 2003","M. Van der Krogt, J. J. Bregman, M. Wisse, A. M. Doorenbosch, J.\nHatlaar, H. Collins: How Crouch Gait Can Dynamically Induce Stiff-\nKnee Gait, Annals of Biomedical Engineering, Vol. 38(4), pp.1593–\n1606, 2010","A. Sebsadji: Evaluation of a Surgery Decision Maker Tool, Ph.D.\nThesis, Evry Val D'Essonne University - UFR Science and Technology,\n2011","D. H. Sutherland: The Evolution of Clinical Gait Analysis, Part l:\nKinesiological EMG, Gait and Posture, Vol.14, pp.61–70, 2001; A.L.\nHof, H. Elzinga, W. Grimmius, J. P. K. Halbertsma : Speed\nDependence of Averaged EMG Profiles in Walking, Gait and Posture,\nVol.16, pp.78-86, 2002; M. Kadaba, H. Ramakrishnan, M. Wootten, J.\nGainey, G. Gorton, G, Cochran : Repeatability of Kinematic, Kinetic,\nand Electromyographic Data in Normal Adult Gait, J. Orthop. Res.,\nVol.7(6), pp.849860, 1989; M. E. Wooton, M. P. Kadaba, G. V. B.\nCochran : Dynamic Electromyography, II. Normal Patterns during Gait,\nJ. Orthop. Res., Vol.8(2), pp.25965, 1990; A. L. Hof,, H. Elzinga, W.\nGrimmius, J. P. K. Halbertsma : Speed Dependence of Averaged EMG\nProfiles in Walking, Gait and Posture, Vol.16(1), pp.7886, 2002\n[10] D. H. Sutherland: The Evolution of Clinical Gait Analysis, Part lI:\nKinematics, Gait and Posture, Vol.16, pp.159–179, 2002; M.L. Linden,\nA. M. van der. Kerr, M. E. Hazlewood, S. J. Hillman, J. E. Robb :\nKinematic and Kinetic Gait Characteristics of Normal Children Walking\nat a Range of Clinically Relevant Speeds, J. PediatrOrthop. Vol.22,\npp.800–806, 2002;\n[11] D. H. Sutherland:The Evolution of Clinical Gait Analysis, Part III:\nKinetics and Energy Assessment, Gait and Posture, Vol.21, pp.447–\n461, 2005\n[12] A. Cornuejols, L. Miclet : Apprentissage Artificiel - Concepts et\nAlgorithmes, Ed. Algorithmes, Paris 2010\n[13] B. W. Stansfield, M. E. Hazlewood, S. J. Hillman, A. M. Lawson, I. R.\nLoudon, A. M. Mann : Sagittal Joint Angles, Moments and Powers are\nPredominantly Characterized by Speed of Progression, not Age, in 7 to\n12 Years Old Normal Children Walking at Self Selected Speeds, J.\nPediatr. Orthop., Vol.21, pp.403–11, 2001\n[14] E. Growney, D. Meglan, M. Johnson, T. Cahalan, K. An : Repeated\nMeasures of Adult Normal Walking Using a Video Tracking System,\nGait and Posture, Vol.6(2), pp.147162, 1997\n[15] B. W. Stansfield, M. E. Hazlewood, S. J. Hillman, A. M. Lawson, I. R.\nLoudon, A. M. Mann : Normalization of Gait Data in Children, Gait\nand Posture, Vol.17, pp.81–87, 2003\n[16] P. N. Grimshaw, P. Marques-Bruna, A. Salo, N. Messenger : The 3-\ndimensional Kinematics of the Walking Gait Cycle of Children Aged\nbetween 10 and 24 Months: Cross Sectional and Repeated Measures,\nGait and Posture, Vol.7(1), pp.715, 1998\n[17] B. W. Stansfield, S. J. Hillman, M. E. Hazlewood : Regression Analysis\nof Gait Parameters with Speed in Normal Children Walking at Selfselected\nSpeeds, Gait and Posture, Vol.23(3), pp.28894, 2006\n[18] D. W. Grieve, R. I. Gear : The Relationship between Length of Stride,\nStep Frequency, Time of Swing and Speed of Walking for Children and\nAdults, Ergonomics, Vol.5, pp.379–399, 1965"]}

Unmanned Aerial Systems (UAS) are extensively used in diverse fields, wherever inexpensive and easy-to-deploy platforms are required for close-range remote sensing. Applications proposed in archaeology to date include ortho-photography and 3-D modeling. On the other hand, use of image processing and feature detection methods, well developed in other fields is hardly used. After reviewing technologies and methods for UAS-based surveying and surface modeling, we propose feature detection methods (e.g. line detection, texture segmentation) dedicated to extraction of structures in the images that are significant for archaeological survey, planning, and documentation and show results on selected case studies.

International audience; [1] Air permeability is measured in the fractured crystalline rocks of the Roselend Natural Laboratory (France). Single-hole pneumatic injection tests as well as differential barometric pressure monitoring are conducted on scales ranging from 1 to 50 m, in both shallow and deep boreholes, as well as in an isolated 60 m 3 chamber at 55 m depth. The field experiments are interpreted using numerical simulations in equivalent homogeneous porous media with their real 3-D geometry in order to estimate pneumatic parameters. For pneumatic injection tests, steady-state data first allow to estimate air permeability. Then, pressure recovery after a pneumatic injection test allows to estimate the air-filled porosity. Comparison between the various studied cases clarifies the influence of the boundary conditions on the accuracy of the often used 1-D estimate of air permeability. It also shows that permeabilities correlate slightly with fracture density. In the chamber, a 1 order-of-magnitude difference is found between the air permeabilities obtained from pneumatic injection tests and from differential barometric pressure monitoring. This discrepancy is interpreted as a scale effect resulting from the approximation of the heterogeneous fractured rock by a homogeneous numerical model. The difference between the rock volumes investigated by pneumatic injection tests and by differential barometric pressure monitoring may also play a role. No clear dependence of air permeability on saturation has been found so far. Citation: Guillon, S., M. T. Vu, E. Pili, and P. M. Adler (2013), Field and numerical determinations of pneumatic flow parameters of unsaturated fractured porous rocks on various scales, Water Resour.

Three-dimensional models of environments can be very useful and are commonly employed in areas such as robotics, art and architecture, facility management, water management, environmental/industrial/urban planning and documentation. A 3-D model is typically composed of a large number of measurements. When 3-D models of environments need to be transmitted or stored, they should be compressed efficiently to use the capacity of the communication channel or the storage medium effectively. We propose a novel compression technique based on compressive sampling applied to sparse representations of 3-D laser range measurements. The main issue here is finding highly sparse representations of the range measurements, since they do not have such representations in common domains, such as the frequency domain. To solve this problem, we develop a new algorithm to generate sparse innovations between consecutive range measurements acquired while the sensor moves. We compare the sparsity of our innovations with others generated by estimation and filtering. Furthermore, we compare the compression performance of our lossy compression method with widely used lossless and lossy compression techniques. The proposed method offers a small compression ratio and provides a reasonable compromise between the reconstruction error and processing time. © 2012 The Author 2012. Published by Oxford University Press on behalf of The British Computer Society. All rights reserved.

Our study deals with a design of suitable test rig, which can help in determining the load bearing capacity, pressure distribution of a journal bearing. Present project work is about designing a test rig, which can be further utilized to check on the behavior of different materials as may be proposed in the design of journal bearing. Therefore the study involves theoretical aspects on the working principle of a journal bearing, numerical calculation and finally a 3D model of the test rig. The sole purpose of designing a test rig is to make it an economical design and yet fulfilling its purpose for conducting experiments. Realization of the project is achieved through 3D modeling and 2D drawing using Autodesk inventor. Test rig will allow the end user to visualize the behavior of any bearing under different working conditions.

This work aims at accurate estimation of the pose of a close-range 3-D modeling device in real-time, at high-rate, and solely from its own images. In doing so, we replace external positioning systems that constrain the system in size, mobility, accuracy, and cost. At close range, accurate pose tracking from image features is hard because feature projections do not only drift in the face of rotation but also in the face of translation. Large, unknown feature drifts may impede real-time feature tracking and subsequent pose estimation---especially with concurrent operation of other 3-D sensors on the same computer. The problem is solved in Ref. [1] by the partial integration of readings from a backing inertial measurement unit (IMU). In this work we avoid using an IMU by improved feature matching: full utilization of the current state estimation (including structure) during feature matching enables decisive modifications of the matching parameters for more efficient tracking---we hereby follow the Active Matching paradigm.

A decade ago, 3D content was restricted to a few applications – mainly games, 3D graphics andscientific simulations. Nowadays, thanks to the development cheap and efficient specialized renderingdevices, 3D objects are ubiquitous. Virtually all devices with a display – from a large visualizationclusters to smart phones – now integrate 3D rendering capabilities. Therefore, 3D applications arenow far more diverse than a few years ago, and include for example real-time virtual and augmentedreality, as well as 3D virtual worlds. In this context, there is an ever increasing need for efficient toolsto transmit and visualize 3D content.In addition, the size of 3D meshes always increases with accuracy of representation. On one hand,recent 3D scanners are able to digitalize real-world objects with a precision of a few micrometers, andgenerate meshes with several hundred million elements. On the other hand, numerical simulationsalways require finer meshes for better accuracy, and massively parallel simulation methods now generatemeshes with billions of elements. In this context, 3D data compression – in particular 3D meshcompression – services are of strategic importance.The previous decade has seen the development of many efficient methods for encoding polygonalmeshes. However, these techniques are no longer adapted to the current context, because they supposethat encoding and decoding are symmetric processes that take place on the same kind of hardware.In contrast, remote 3D content will typically be created, compressed and served by high-performancemachines, while exploitation (e.g. visualization) will be carried out remotely on smaller – possiblyhand held – devices that cannot handle large meshes as a whole. This makes mesh compression anintrinsically asymmetric process.Our objective in this dissertation is to address the compression of these large meshes. In particularwe study random-accessible compression schemes, that consider mesh compression as an asymmetricproblem where the compressor is an off-line process and has access to a large amount of resources,while decompression is a time-critical process with limited resources. We design such a compressionscheme and apply it to interactive visualization.In addition, we propose a streaming compression algorithm that targets the very large hexahedralmeshes that are common in the context of scientific numerical simulation. Using this scheme, we areable to compress meshes of 50 million hexahedra in less than two minutes using a few megabytes ofmemory.Independently from these two specific algorithms, we develop a generic theoretical framework toaddress mesh geometry compression. This framework can be used to derive geometry compressionschemes for any mesh compression algorithm based on a predictive paradigm – which is the case of thelarge majority of compression schemes. Using this framework, we derive new geometry compressionschemes that are compatible with existing mesh compression algorithms but improve compressionratios – by approximately 9% on average. We also prove the optimality of some other schemes underusual smoothness assumptions., Il y a une décennie, le contenu numérique virtuel était limité à quelques applications – majoritairementles jeux vidéos, les films en 3D et la simulation numérique. Aujourd’hui, grâce à l’apparition de cartes graphiques performantes et bon marché, les objets 3D sont utilisés dans de nombreuses applications. A peu près tous les terminaux possédant des capacités d’affichage – des clusters de visualisation haute performance jusqu’aux smart phones – intègrent maintenant une puce graphique qui leur permet de faire du rendu 3D. Ainsi, les applications 3D sont bien plus variées qu’il y a quelques années. On citera par exemple la réalité virtuelle et augmentée en temps réel ou les mondes virtuels 3D. Dans ce contexte, le besoin de méthodes efficaces pour la transmission et la visualisation des données 3D est toujours plus pressant. De plus, la taille des maillages 3D ne cesse de s’accroître avec la précision de la représentation. Par exemple, les scanners 3D actuels sont capables de numériser des objets du monde réel avec une précision de seulement quelques micromètres, et génèrent des maillages contenant plusieurs centaines de millions d’´el´ements. D’un autre côté, une précision accrue en simulation numérique requiert des maillages plus fins, et les méthodes massivement parallèles actuelles sont capables de travailler avec des milliards de mailles. Dans ce contexte, la compression de ces données – en particulier la compression de maillages – est un enjeu important. Durant la décennie passée, de nombreuses méthodes ont été développées pour coder les maillages polygonaux. Néanmoins, ces techniques ne sont plus adaptées au contexte actuel, car elles supposentque la compression et la d´ecompression sont des processus sym´etriques qui ont lieu sur un mat´erielsimilaire. Dans le cadre actuel, au contraire, le contenu 3D se trouve cr´e´e, compressé et distribué par des machines de hautes performances, tandis que l’exploitation des données – par exemple, la visualisation – est effectuée à distance sur des périphériques de capacité plus modeste – éventuellement mobiles – qui ne peuvent traiter les maillages de grande taille dans leur int´egralité. Ceci fait de lacompression de maillage un processus intrinsèquement asymétrique.Dans cette thèse, notre objectif est d’étudier et de proposer des méthodes pour la compression de maillages de grande taille. Nous nous intéressons plus particulièrement aux méthodes d’accès aléatoire, qui voient la compression comme un problème intrinsèquement asymétrique. Dans ce modèle, le codeur a accès à des ressources informatiques importantes, tandis que la décompression estun processus temps réel (souple) qui se fait avec du matériel de plus faible puissance. Nous décrivons un algorithme de ce type et l’appliquons au cas de la visualisation interactive. Nous proposons aussi un algorithme streaming pour compresser des maillages hexaèdriques de très grande taille utilisés dans le contexte de la simulation numérique. Nous sommes ainsi capables decompresser des maillages comportant de l’ordre de 50 millions de mailles en moins de deux minutes, et en n’utilisant que quelques mégaoctets de mémoire vive. Enfin, nous proposons, indépendamment de ces deux algorithmes, un cadre théorique général pour améliorer la compression de géométrie. Cet algorithme peut être utilisé pour développer des méthodes de prédiction pour n’importe quel algorithme basé sur un paradigme prédictif – ce qui est la cas dela majorité des méthodes existantes. Nous dérivons ainsi des schémas de prédictions compatibles avec plusieurs méthodes de la littérature. Ces schémas augmentent les taux de compression de 9% enmoyenne. Sous des hypothèses usuelles, nous utilisons aussi ces résultats pour prouver l’optimalité de certains algorithmes existants.

A decade ago, 3D content was restricted to a few applications – mainly games, 3D graphics andscientific simulations. Nowadays, thanks to the development cheap and efficient specialized renderingdevices, 3D objects are ubiquitous. Virtually all devices with a display – from a large visualizationclusters to smart phones – now integrate 3D rendering capabilities. Therefore, 3D applications arenow far more diverse than a few years ago, and include for example real-time virtual and augmentedreality, as well as 3D virtual worlds. In this context, there is an ever increasing need for efficient toolsto transmit and visualize 3D content.In addition, the size of 3D meshes always increases with accuracy of representation. On one hand,recent 3D scanners are able to digitalize real-world objects with a precision of a few micrometers, andgenerate meshes with several hundred million elements. On the other hand, numerical simulationsalways require finer meshes for better accuracy, and massively parallel simulation methods now generatemeshes with billions of elements. In this context, 3D data compression – in particular 3D meshcompression – services are of strategic importance.The previous decade has seen the development of many efficient methods for encoding polygonalmeshes. However, these techniques are no longer adapted to the current context, because they supposethat encoding and decoding are symmetric processes that take place on the same kind of hardware.In contrast, remote 3D content will typically be created, compressed and served by high-performancemachines, while exploitation (e.g. visualization) will be carried out remotely on smaller – possiblyhand held – devices that cannot handle large meshes as a whole. This makes mesh compression anintrinsically asymmetric process.Our objective in this dissertation is to address the compression of these large meshes. In particularwe study random-accessible compression schemes, that consider mesh compression as an asymmetricproblem where the compressor is an off-line process and has access to a large amount of resources,while decompression is a time-critical process with limited resources. We design such a compressionscheme and apply it to interactive visualization.In addition, we propose a streaming compression algorithm that targets the very large hexahedralmeshes that are common in the context of scientific numerical simulation. Using this scheme, we areable to compress meshes of 50 million hexahedra in less than two minutes using a few megabytes ofmemory.Independently from these two specific algorithms, we develop a generic theoretical framework toaddress mesh geometry compression. This framework can be used to derive geometry compressionschemes for any mesh compression algorithm based on a predictive paradigm – which is the case of thelarge majority of compression schemes. Using this framework, we derive new geometry compressionschemes that are compatible with existing mesh compression algorithms but improve compressionratios – by approximately 9% on average. We also prove the optimality of some other schemes underusual smoothness assumptions., Il y a une décennie, le contenu numérique virtuel était limité à quelques applications – majoritairementles jeux vidéos, les films en 3D et la simulation numérique. Aujourd’hui, grâce à l’apparition de cartes graphiques performantes et bon marché, les objets 3D sont utilisés dans de nombreuses applications. A peu près tous les terminaux possédant des capacités d’affichage – des clusters de visualisation haute performance jusqu’aux smart phones – intègrent maintenant une puce graphique qui leur permet de faire du rendu 3D. Ainsi, les applications 3D sont bien plus variées qu’il y a quelques années. On citera par exemple la réalité virtuelle et augmentée en temps réel ou les mondes virtuels 3D. Dans ce contexte, le besoin de méthodes efficaces pour la transmission et la visualisation des données 3D est toujours plus pressant. De plus, la taille des maillages 3D ne cesse de s’accroître avec la précision de la représentation. Par exemple, les scanners 3D actuels sont capables de numériser des objets du monde réel avec une précision de seulement quelques micromètres, et génèrent des maillages contenant plusieurs centaines de millions d’´el´ements. D’un autre côté, une précision accrue en simulation numérique requiert des maillages plus fins, et les méthodes massivement parallèles actuelles sont capables de travailler avec des milliards de mailles. Dans ce contexte, la compression de ces données – en particulier la compression de maillages – est un enjeu important. Durant la décennie passée, de nombreuses méthodes ont été développées pour coder les maillages polygonaux. Néanmoins, ces techniques ne sont plus adaptées au contexte actuel, car elles supposentque la compression et la d´ecompression sont des processus sym´etriques qui ont lieu sur un mat´erielsimilaire. Dans le cadre actuel, au contraire, le contenu 3D se trouve cr´e´e, compressé et distribué par des machines de hautes performances, tandis que l’exploitation des données – par exemple, la visualisation – est effectuée à distance sur des périphériques de capacité plus modeste – éventuellement mobiles – qui ne peuvent traiter les maillages de grande taille dans leur int´egralité. Ceci fait de lacompression de maillage un processus intrinsèquement asymétrique.Dans cette thèse, notre objectif est d’étudier et de proposer des méthodes pour la compression de maillages de grande taille. Nous nous intéressons plus particulièrement aux méthodes d’accès aléatoire, qui voient la compression comme un problème intrinsèquement asymétrique. Dans ce modèle, le codeur a accès à des ressources informatiques importantes, tandis que la décompression estun processus temps réel (souple) qui se fait avec du matériel de plus faible puissance. Nous décrivons un algorithme de ce type et l’appliquons au cas de la visualisation interactive. Nous proposons aussi un algorithme streaming pour compresser des maillages hexaèdriques de très grande taille utilisés dans le contexte de la simulation numérique. Nous sommes ainsi capables decompresser des maillages comportant de l’ordre de 50 millions de mailles en moins de deux minutes, et en n’utilisant que quelques mégaoctets de mémoire vive. Enfin, nous proposons, indépendamment de ces deux algorithmes, un cadre théorique général pour améliorer la compression de géométrie. Cet algorithme peut être utilisé pour développer des méthodes de prédiction pour n’importe quel algorithme basé sur un paradigme prédictif – ce qui est la cas dela majorité des méthodes existantes. Nous dérivons ainsi des schémas de prédictions compatibles avec plusieurs méthodes de la littérature. Ces schémas augmentent les taux de compression de 9% enmoyenne. Sous des hypothèses usuelles, nous utilisons aussi ces résultats pour prouver l’optimalité de certains algorithmes existants.

The design and evaluation of virtual learning environments for construction and surveying students is presented in this paper; by combining virtual learning environment and on-site student surveys to model and replicate practice in the architectural heritage sector. The Virtual Learning Environment is enhanced with real live survey projects whereby students collect the data to build virtual historic buildings from onsite surveys using advanced survey equipment. The survey data is modelled in HBIM; Historic Building Information Modelling (HBIM) is currently being developed as a virtual learning tool for construction and surveying students in the Dublin Institute of Technology. HBIM, is a novel solution whereby interactive parametric objects representing architectural elements are constructed from historic data, these elements, including detail behind the scan surface are accurately mapped onto a laser or image based survey. The architectural elements are scripted using a Geometric Descriptive Language GDL. In the case of this project a Virtual Learning Environment is being developed which combines advanced recording and surveying with Building Information Modelling (BIM) to simulate and analyse existing buildings.

Three-dimensional phenomena, related to the fluid dynamic behavior of the plasma and secondary gas in the region between the torch tip and the workpiece, have been studied by means of a 3-D FLUENT-based numerical model, with the final aim of optimizing the design of a prototype monogas plasma arc cutting torch, operating in the range 25-100 A. The details of the spacer for contact cutting geometry and of the metallic substrate with the keyhole are included in the computational domain. The development of a 3-D model was necessary to solve specific design issues that cannot be properly studied by 2-D models, providing also useful results to be compared with experimental evidences coming from diagnostic and cut quality/erosion tests.

Robotbilim, sanat ve mimarlık, çevre planlaması ve dökümantasyonu gibi çeşitli alanlarda ortamların üç boyutlu modellerinden yararlanılır. Üç boyutlu modellerin çok fazla sayıda ölçüm içermesinden dolayı, bu modellerin bir yerden bir yere iletilmesi veya bir yerde saklanması gerektiğinde, haberleşme kanalının veya veri depolama alanının kapasitesini verimli kullanmak için verilerin öncelikle etkili bir biçimde sıkıştırılmaları gerekir. Bu tezde, üç boyutlu lazer uzaklık taramalarını sıkıştırmak için, sıkıştırmalı algılamaya dayanan yeni bir yöntem önerilmektedir. Taramaların frekans alanı gibi yaygın kullanılan alanlarda çok seyrek gösterimlerinin olmamasından dolayı, bunların çok seyrek şekilde temsil edilmesi, bu tezde ele alınan ana sorunlardan biridir. Bu sorunun çözümü için taramaları, lazer uzaklık algılayıcısının hareket yönünde peş peşe alınan ölçümler arasında oluşturulan seyrek değişimlerle temsil eden bir yöntem geliştirilmiştir. Oluşturulan değişimlerin seyrekliği, diğer kestirme ve süzgeçleme yöntemleriyle hesaplanan değişimlerle karşılaştırılmıştır. Ayrıca önerilen kayıplı sıkıştırma yönteminin başarımı, yaygın kullanılan kayıpsız ve kayıplı sıkıştırma yöntemlerinin başarımlarıyla karşılaştırılmıştır. Sonuç olarak, önerilen yöntem kısa sürede ve az kayıpla, büyük oranda sıkıştırma sağlamaktadır. 3-D models of environments can be very useful and are commonly employed in areas such as robotics, art and architecture, environmental planning and documentation. A 3-D model is typically comprised of a large number of measurements. When 3-D models of environments need to be transmitted or stored, they should be compressed efficiently to use the capacity of the communication channel or the storage medium effectively. In this thesis, we propose a novel compression technique based on compressive sampling, applied to sparse representations of 3-D laser range measurements. The main issue here is finding highly sparse representations of the range measurements, since they do not have such representations in common domains, such as the frequency domain. To solve this problem, we develop a new algorithm to generate sparse innovations between consecutive range measurements acquired while the sensor moves. We compare the sparsity of our innovations with others generated by estimation and filtering. Furthermore, we compare the compression performance of our lossy compression method with widely used lossless and lossy compression techniques. The proposed method offers small compression ratio and provides a reasonable compromise between reconstruction error and processing time. 90

Reverse engineering (RE) is a powerful tool for generating a CAD model from the 3D scan data of a physical part that lacks documentation or has changed from the original CAD design of the part. The process of digitizing a part and creating a CAD model from 3D scan data is less time consuming and provides greater accuracy than manually measuring the part and designing the part from scratch in CAD. 3D optical scanning technology is one of the measurement methods which have evolved over the last few years and it is used in a wide range of areas from industrial applications to art and cultural heritage. It is also used extensively in the automotive industry for applications such as part inspections, scanning of tools without CAD definition, scanning the casting for definition of the stock (i.e. the amount of material to be removed from the surface of the castings) model for CAM programs and reverse engineering. In this study two scanning experiments of automotive applications are illustrated. The first one examines the processes from scanning to re-manufacturing the damaged sheet metal cutting die, using a 3D scanning technique and the second study compares the scanned point clouds data to 3D CAD data for inspection purposes. Furthermore, the deviations of the part holes are determined by using different lenses and scanning parameters. Infotron and Tunaoglu companies

In the recent years the use of geothermal energy through implementation of low enthalpy geothermal production systems for both electricity and heating have been growing rapidly in north-western Europe. Geothermal exploration and production takes largely place in sedimentary basins at depths from 2 to 5 km. Geothermal activities can take considerable advantage of a wealth of existing oil and gas data. To governmental bodies, such as geological surveys, it is a major challenge to put relevant oil and gas data and derived subsurface structural, temperature, and flow property models available to the geothermal community and to facilitate in quantitative assessment of geothermal potential of targeted areas, for both heat and electricity production (EGS) . In order to face this challenge, TNO has developed a public web-based 3D information system connected to a geothermal performance assessment tool. The public information system (thermoGIS) includes high resolution 3D geological models covering the complete onshore of the Netherlands, outlining key geothermal reservoirs and allowing to assess relevant parameters and underlying uncertainties therein. State-of-the-art 3D modeling techniques have been used and developed to obtain the reservoir structures, flow properties and temperatures, using constraints from over a thousand deep wells, and detailed subsurface mapping from 3D and 2D seismic. Users can obtain key reservoir parameters, and underlying uncertainties at any location and for any reservoir. In an automated workflow these parameters are fed into the performance assessment tool, in order to asses the probability of success to meet minimum requirements on key performance indicators such as Coefficient of Performance (COP), power produced, and Unit Technical Cost (UTC). The use of the ThermoGIS will aid exploration business decisions and Dutch governmental institutions, law makers and insurance companies.

In the recent years the use of geothermal energy through implementation of low enthalpy geothermal production systems for both electricity and heating have been growing rapidly in north-western Europe. Geothermal exploration and production takes largely place in sedimentary basins at depths from 2 to 5 km. Geothermal activities can take considerable advantage of a wealth of existing oil and gas data. To governmental bodies, such as geological surveys, it is a major challenge to put relevant oil and gas data and derived subsurface structural, temperature, and flow property models available to the geothermal community and to facilitate in quantitative assessment of geothermal potential of targeted areas, for both heat and electricity production (EGS) . In order to face this challenge, TNO has developed a public web-based 3D information system connected to a geothermal performance assessment tool. The public information system (thermoGIS) includes high resolution 3D geological models covering the complete onshore of the Netherlands, outlining key geothermal reservoirs and allowing to assess relevant parameters and underlying uncertainties therein. State-of-the-art 3D modeling techniques have been used and developed to obtain the reservoir structures, flow properties and temperatures, using constraints from over a thousand deep wells, and detailed subsurface mapping from 3D and 2D seismic. Users can obtain key reservoir parameters, and underlying uncertainties at any location and for any reservoir. In an automated workflow these parameters are fed into the performance assessment tool, in order to asses the probability of success to meet minimum requirements on key performance indicators such as Coefficient of Performance (COP), power produced, and Unit Technical Cost (UTC). The use of the ThermoGIS will aid exploration business decisions and Dutch governmental institutions, law makers and insurance companies.

In the last two years, we have been using the Visualization Toolkit (VTK) as a tool for teaching ''3D Modelling and Visualization'', an elective course offered to Computer Engineering students. Students start by using OpenGL and, afterwards, use VTK in half of their lab classes, in order to accomplish some tasks and acquire knowledge on its features and functionalities. They are also required to develop a visualization application based on VTK. We first present the motivation for using VTK and the main features of the ''3D Modelling and Visualization'' course. Afterwards, we describe some of the most successful projects developed by our students. Then, we globally analyse the effectiveness of using VTK, and present the results of a questionnaire handed out to the students who attended the course in the last semester.

The use of three-dimensional computer models in archaeological projects is a relatively new but rapidly growing area, both as a means of presenting research to the public and also as an aid to interpretation. This work uses the House of the Surgeon in Pompeii as a case study and seeks to illustrate the most effective ways to display information to a range of audiences. In using the flexibility of computer modelling techniques it seeks to show that the levels of detail in a 3-D computer model can be tailored to individual circumstances to produce the most effective result.

Date of Conference: 11-13 June 2007 Conference name: IEEE 15th Signal Processing and Communications Applications, 2007 Dikdörtgensel olmayan dalgacık dönüşümüne dayalı çok çözünürlüklü üç boyutlu model sıkıştırılması için iki yöntem önerilmektedir. Bunlar Sıradüzensel Ağaç Yapılarının Kümelere Bölütlenmesi (Set Partitioning In Hierarchical Trees - SPIHT) ve JPEG2000 tekniklerine dayanmaktadır. Üç boyutlu modeller düzenli ızgara yapılar üzerinde tanımlı iki boyutlu imgelere dönüştürülmekte, ve bu gösterim bağlanırlıkla yönlendirilmiş uyarlamalı dalgacık dönüşümünden geçirilerek ortaya çıkan dalgacık kümesi verisi SPITH veya JPEG2000 yöntemlerinden biri uygulanarak bit dizgisine dönüştürülmektedir. SPIHT ile elde edilen bit dizgisinin değişik uzunluklardaki bölümlerinden modelin değişik çözünürlüklerde geri çatmak mümkün olduğundan önerilen bu yöntem modellerin aşamalı gösterimine olanak sağlamaktadır. Dalgacık dönüşümü verilerinin SPIHT ile kodlanmasıyla elde edilen sonuç JPEG2000 ve MPEG-3DGC ile yapılan kodlamanın sonucundan daha başarılı olmuştur. Two compression frameworks that are based on a Set Partitioning In Hierarchical Trees (SPIHT) and JPEG2000 methods are proposed. The 3D mesh is first transformed to 2D images on a regular grid structure. Then, this image-like representation is wavelet transformed employing an adaptive predictor that takes advantage of the connectivity information of mesh vertices. Then SPIHT or JPEG2000 is applied on the wavelet domain data. The SPIHT based method is progressive because the resolution of the reconstructed mesh can be changed by varying the length of the one-dimensional data stream created by SPIHT algorithm. The results of the SPIHT based algorith is observed to be superior to JPEG200 based mesh coder and MPEG-3DGC in rate-distortion.