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Dissertations / Theses on the topic 'Computer vision simulation'
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Sourtzinos, Panagiotis. "Vision-based analysis and simulation of pedestrian dynamics." Thesis, Kingston University, 2016. http://eprints.kingston.ac.uk/35839/.
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The aim of this thesis is to examine the applicability of computer vision to analyze pedestrian and crowd characteristics, and how pedestrain simulation for shopping environments can be driven from the visual perception of the simulated pedestrians. More specifically, two frameworks for pedestrian speed profile estimation are designed and implemented. The first address the problem of speed estimation for people moving parallel to the image plane on a flat surface, while the other tries to estimate the speed of people walking on stairs moving while their trajectories and being perpendicular on the image plane. Both approaches aim to localise the foot of the pedestrains, and by identifying their steps measure their speed. Except from measuring the speed of pedestrains, a crowd counting system using Convolutional Neural Networks is created by exploiting the background spatial persistence of a whole image in the temporal domain, and furthermore by fusing consecutive temporal counting information in the systme further refines its estimates. Finally a novel memory-free cognitive framework for pedestrian shopping behaviour is presented where the simulated pedestrians use as route choice model their visual perception. Agents moving in an environment and equipped with an activity agenda. use their vision to select not only their root choices but also the shops that they visit.
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Pursel, Eugene Ray. "Synthetic vision : visual perception for computer generated forces using the programmable graphics pipeline /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Sep%5FPursel.pdf.
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Thesis (M.S. in Modeling, Virtual Environments and Simulation (MOVES))--Naval Postgraduate School, Sept. 2004.Thesis Advisor(s): Christian J. Darken. Includes bibliographical references (p. 93-95). Also available online.
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Gong, Shaogang. "Parallel computation of visual motion." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238149.
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Beilstein, Del L. "Visual simulation of night vision goggles in a chromakeyed, augmented, virtual environment." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FBeilstein.pdf.
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Thesis (M.S. in Modeling, Virtual Environments, and Simulation)--Naval Postgraduate School, June 2003.Thesis advisor(s): Rudolph P. Darken, Joseph A. Sullivan. Includes bibliographical references (p. 77). Also available online.
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Sarrabezolles, Louise. "Formalization and Simulation of Bio-Inspired On-chip Dynamic Attractors for Low Power Computer Vision." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAE001.
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Il devient difficile aujourd'hui de maintenir une amélioration des performances en vision artificielle tout en gardant une capacité de traitement embarqué temps-réel. L'étude du modèle de vision de l'être humain apporte différentes inspirations pour répondre à ce problème. La méthode utilisée par le composant bio-inspirée de BVS-Tech a attiré l'attention de la communauté par ses caractéristiques matérielles et sa mise en oeuvre dans plusieurs projets industriels. Mais l'absence de formalisme mathématique et de simulation de la méthode ne permet pas une analyse des performances de la méthode sur des bases académique. Cette thèse s'est appliquée à approfondir, formaliser et reproduire le concept du système. La modélisation mathématique et la création d'un simulateur ont permis de valider le concept de la méthode sur un set d'images artificielles et d'analyser son comportement et ses performances dans une application spécifique. Les résultats prometteurs mettent cependant en avant la forte dépendance paramétrique de la méthode. Deux extensions de la méthode ont récemment été proposées : l'adaptation automatique des caractéristiques d'entrée d'une part, et la mise en place d'un suivi de cibleHigh performance in real-time is one of today's challenge of embedded Computer Vision. The study of the human vision models inspires several solutions. The bio-inspired method used by the BVS-Tech component caught the attention of the community with its hardware characteristics and its application in different industrial projects. However, the lack of mathematical formalization and simulation of the method does not allow to analyse it on academical databases.This thesis focused on the understanding, the formalization and the reproduction of the method. The mathematical model and the simulator produced allowed to validate the concept on artificial images, to analyse its behaviour and performances in a specific application. The promising results shows, however, the strong influence of several parameters. Two extensions of the method have recently been proposed: the automatic adaptation of the feature inputs and the prediction integration
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Long, Steven A. "Developing and implementing a computer vision based surgical simulator for hip wire navigation." Thesis, University of Iowa, 2016. https://ir.uiowa.edu/etd/5555.
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Orthopaedic residency training is in the midst of a paradigm shift. Recent mandates from the Residency Review Committee (RRC) for Orthopaedic Surgery and the American Board of Orthopaedic Surgery (ABOS) are requiring that programs must provide structured motor skills training to first year residents. Although other surgical fields such as laparoscopic surgery have been using simulation tools to train incoming residents for over a decade, the orthopaedic field has lagged behind in developing these training tools. Given the need for orthopaedic training devices and the lack of currently available solutions to residency programs, this work has focused on developing a surgical simulator for the task of hip guide wire navigation. Hip wire navigation was targeted for this work because it is a core competency skill for surgical residents and few options currently exist for training residents on this task.
Much of this work focuses on the development of the wire navigation simulator. The simulator has six main components; a single camera interfaced with a Raspberry Pi (a credit-card sized computer), a series of three mirrors, a surrogate femur, a guide wire driver, a laser etched guide wire, and a laptop. These components interact to create virtual radiograph images that the resident can use to place the guide wire inside the bone. The goal in developing this simulator is to provide a platform which enables residents to acquire the skill of hip wire navigation in a safe environment and eventually transfer that skill into the operating room.
Assessment of the simulator has shown that the guide wire can be located in bone within 1.5mm of its true position and less than a degree of its true trajectory. This level of accuracy is sufficient for providing residents with a training tool to practice their technique on.
In training with resident surgeons, initial trends show that practicing with the simulator can result in an improvement in one’s technique. Residents who have trained with the simulator show a decrease in both the amount of radiographic images required to complete the procedure and the amount of time required to perform the procedure in a pseudo operating room environment. While more work is needed to be done to show the significance of this trend, this work has achieved its goal of providing residents with a safe platform for practicing the task of hip guide wire navigation.
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Fichtl, Severin Andreas Thomas-Morus. "Developmental learning of preconditions for means-end actions from 3D vision." Thesis, University of Aberdeen, 2015. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=227931.
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Specifically equipped and programmed robots are highly successful in controlled industrial environments such as automated production lines. For the transition of robots from such controlled uniform environments to unconstrained household environments with a large range of conditions and variations, a new paradigm is needed to prepare the robots for deployment. Robots need to be able to quickly adapt to their changing environments and learn on their own how to solve their tasks in novel situations. This dissertation focusses on the aspect of learning to predict the success of two-object means-end actions in a developmental way. E.g. the action of bringing one object into reach by pulling another, where the one object is on top of the other. Here it is the “on top” relation that affects the success of the action. Learning the preconditions for complex means-end actions via supervised learning can take several thousand training samples, which is impractical to generate, hence more rapid learning capabilities are necessary. Three contributions of this dissertation are used to solve the learning problem. 1. Inspired by infant psychology this dissertation investigates an approach to intrinsic motivation that is based on active learning, guiding the robot's exploration to create experience useful for improving classification performance. 2. This dissertation introduces histogram based 3D vision features that encode the relative spatial relations between surface points of object pairs, allowing a robot to reliably recognise the important spatial categories that affect means-end action outcomes. 3. Intrinsically encoded experience is extracted into symbolic category knowledge, encoding higher level abstract categories. These symbolic categories are used for knowledge transfer by using them to extend the state space of action precondition learning classifiers. Depending on the actions and their preconditions, the contributions of this dissertation enable a robot to achieve success prediction accuracies above 85% with ten training samples instead of approximately 1000 training samples that would otherwise be required. These results can be achieved when (a) the action preconditions can be easily identified from the used vision features or (b) the action preconditions to be learnt rest upon already existing knowledge, then it is possible to achieve these results by reusing the existing knowledge. This dissertation demonstrates, in simulation, an alternative to handcoding the knowledge required for a robot to interact with and manipulate objects in the environment. It shows that rapid learning, grounded in autonomous exploration, can be feasible if the necessary vision features are constructed and if existing knowledge is consistently reused.
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Dowling, Jason Anthony. "Mobility enhancement using simulated artificial human vision." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16380/.
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The electrical stimulation of appropriate components of the human visual system can result in the perception of blobs of light (or phosphenes) in totally blind patients. By stimulating an array of closely aligned electrodes it is possible for a patient to perceive very low-resolution images from spatially aligned phosphenes. Using this approach, a number of international research groups are working toward developing multiple electrode systems (called Artificial Human Vision (AHV) systems or visual prostheses) to provide a phosphene-based substitute for normal human vision. Despite the great promise, there are currently a number of constraints with current AHV systems. These include limitations in the number of electrodes which can be implanted and the perceived spatial layout and display frequency of phosphenes. Therefore the development of computer vision techniques that can maximise the visualisation value of the limited number of phosphenes would be useful in compensating for these constraints. The lack of an objective method for comparing different AHV system displays, in addition to comparing AHV systems and other blind mobility aids (such as the long cane), has been a significant problem for AHV researchers. Finally, AHV research in Australia and many other countries relies strongly on theoretical models and animal experimentation due to the difficult of prototype human trials. Because of this constraint the experiments conducted in this thesis were limited to simulated AHV devices with normally sighted research participants and the true impact on blind people can only be regarded as approximated. In light of these constraints, this thesis has two general aims. The first aim is to investigate, evaluate and develop effective techniques for mobility assessment which will allow the objective comparison of different AHV system phosphene presentation methods. The second aim is to develop a useful display framework to guide the development of AHV information presentation, and use this framework to guide the development of an AHV simulation device. The first research contribution resulting from this work is a conceptual framework based on literature reviews of blind and low vision mobility, AHV technology, and computer vision. This framework incorporates a comprehensive number of factors which affect the effectiveness of information presentation in an AHV system. Experiments reported in this thesis have investigated a number of these factors using simulated AHV with human participants. It has been found that higher spatial resolution is associated with accurate walking (reduced veering), whereas higher display rate is associated with faster walking speeds. In this way it has been demonstrated that the conceptual framework supports and guides the development of an adaptive AHV system, with the dynamic adjustment of display properties in real-time. The second research contribution addresses mobility assessment which has been identified as an important issue in the AHV literature. This thesis presents the adaptation of a mobility assessment method from the blind and low vision literature to measure simulated AHV mobility performance using real-time computer based analysis. This method of mobility assessment (based on parameters for walking speed, obstacle contacts and veering) is demonstrated experimentally in two different indoor mobility courses. These experiments involved sixty-five participants wearing a head-mounted simulation device. The final research contribution in this thesis is the development and evaluation of an original real-time looming obstacle detector, based on coarse optical flow, and implemented on a Windows PocketPC based Personal Digital Assistant (PDA) using a CF card camera. PDA based processors are a preferred main processing platform for AHV systems due to their small size, light weight and ease of software development. However, PDA devices are currently constrained by restricted random access memory, lack of a floating point unit and slow internal bus speeds. Therefore any real-time software needs to maximise the use of integer calculations and minimise memory usage. This contribution was significant as the resulting device provided a selection of experimental results and subjective opinions.
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Ramswamy, Lakshmy. "PARZSweep a novel parallel algorithm for volume rendering of regular datasets /." Master's thesis, Mississippi State : Mississippi State University, 2003. http://library.msstate.edu/etd/show.asp?etd=etd-04012003-140443.
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Chaudhary, Gautam. "RZSweep a new volume-rendering technique for uniform rectilinear datasets /." Master's thesis, Mississippi State : Mississippi State University, 2003. http://library.msstate.edu/etd/show.asp?etd=etd-04012003-141739.
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Keriven, Renaud. "Equations aux dérivées partielles, Evolutions de courbes et de surfaces et espaces d'echelle: Applications à la vision par ordinateur." Phd thesis, Ecole des Ponts ParisTech, 1997. http://tel.archives-ouvertes.fr/tel-00005617.
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Kolesnik, Paul. "Conducting gesture recognition, analysis and performance system." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81499.
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A number of conducting gesture analysis and performance systems have been developed over the years. However, most of the previous projects either primarily concentrated on tracking tempo and amplitude indicating gestures, or implemented individual mapping techniques for expressive gestures that varied from research to research. There is a clear need for a uniform process that could be applied toward analysis of both indicative and expressive gestures. The proposed system provides a set of tools that contain extensive functionality for identification, classification and performance with conducting gestures. Gesture recognition procedure is designed on the basis of Hidden Markov Model (HMM) process. A set of HMM tools are developed for Max/MSP software. Training and recognition procedures are applied toward both right-hand beat- and amplitude-indicative gestures, and left-hand expressive gestures. Continuous recognition of right-hand gestures is incorporated into a real-time gesture analysis and performance system in Eyesweb and Max/MSP/Jitter environments.
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Li, Meng. "On study of lip segmentation in color space." HKBU Institutional Repository, 2014. https://repository.hkbu.edu.hk/etd_oa/42.
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This thesis mainly addresses two issues: 1) to investigate how to perform the lip segmentation without knowing the true number of segments in advance, and 2) to investigate how to select the local optimal observation scale for each structure from the viewpoint of lip segmentation e.ectively. Regarding the .rst issue, two number of prede.ned segments independent lip segmentation methods are proposed. In the .rst one, a multi-layer model is built up, in which each layer corresponds to one segment cluster. Subsequently, a Markov random .eld (MRF) derived from this model is obtained such that the segmentation problem is formulated as a labeling optimization problem under the maximum a posteriori-Markov random .eld (MAP-MRF) framework. Suppose the pre-assigned number of segments may over-estimate the ground truth, whereby leading to the over-segmentation. An iterative algorithm capable of performing segment clusters and over-segmentation elimination simultaneously is presented. Based upon this algorithm, a lip segmentation scheme is proposed, featuring the robust performance to the estimate of the number of segment clusters. In the second method, a fuzzy clustering objective function which is a variant of the partition entropy (PE) and implemented using Havrda-Charvat’s structural a-entropy is presented. This objective function features that the coincident cluster centroids in pattern space can be equivalently substituted by one centroid with the function value unchanged. The minimum of the proposed objective function can be reached provided that: (1) the number of positions occupied by cluster centroids in pattern space is equal to the truth cluster number, and (2) these positions are coincident with the optimal cluster centroids obtained under PE criterion. In the implementation, the clusters provided that the number of clusters is greater than or equal to the ground truth are randomly initialized. Then, an iterative algorithm is utilized to minimize the proposed objective function. The initial over-partition will be gradually faded out with the redundant centroids superposed over the convergence of the algorithm. For the second issue, an MRF based method with taking local scale variation into account to deal with the lip segmentation problem is proposed. Supposing each pixel of the target image has an optimal local scale from the segmentation viewpoint, the lip segmentation problem can be treated as a combination of observation scale selection and observed data classi.cation. Accordingly, a multi-scale MRF model is proposed to represent the membership map of each input pixel to a speci.c segment and local-scale map simultaneously. The optimal scale map and the corresponding segmentation result are obtained by minimizing the objective function via an iterative algorithm. Finally, based upon the three proposed methods, some lip segmentation experiments are conducted, respectively. The results show the e.cacy of the proposed methods in comparison with the existing counterparts.
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Huang, Jing Ye. "Visual Simulation in virtual abdominal surgery." Thesis, University of Macau, 2012. http://umaclib3.umac.mo/record=b2586278.
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Schodl, Arno. "Adaptive parallelization of model-base head tracking." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/8266.
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Marks, Tim K. "Facing uncertainty 3D face tracking and learning with generative models /." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3196545.
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Thesis (Ph. D.)--University of California, San Diego, 2006.Title from first page of PDF file (viewed February 27, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 143-148).
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Dehlin, Jonas, and Joakim Löf. "Dynamic Infrared Simulation : A Feasibility Study of a Physically Based Infrared Simulation Model." Thesis, Linköping University, Department of Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7993.
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The increased usage of infrared sensors by pilots has created a growing demand for simulated environments based on infrared radiation. This has led to an increased need for Saab to refine their existing model for simulating real-time infrared imagery, resulting in the carrying through of this thesis. Saab develops the Gripen aircraft, and they provide training simulators where pilots can train in a realistic environment. The new model is required to be based on the real-world behavior of infrared radiation, and furthermore, unlike Saab's existing model, have dynamically changeable attributes.
This thesis seeks to develop a simulation model compliant with the requirements presented by Saab, and to develop the implementation of a test environment demonstrating the features and capabilities of the proposed model. All through the development of the model, the pilot training value has been kept in mind.
The first part of the thesis consists of a literature study to build a theoretical base for the rest of the work. This is followed by the development of the simulation model itself and a subsequent implementation thereof. The simulation model and the test implementation are evaluated as the final step conducted within the framework of this thesis.
The main conclusions of this thesis first of all includes that the proposed simulation model does in fact have its foundation in physics. It is further concluded that certain attributes of the model, such as time of day, are dynamically changeable as requested. Furthermore, the test implementation is considered to have been feasibly integrated with the current simulation environment.
A plan concluding how to proceed has also been developed. The plan suggests future work with the proposed simulation model, since the evaluation shows that it performs well in comparison to the existing model as well as other products on the market.
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Nitz, Pettersson Hannes, and Samuel Vikström. "VISION-BASED ROBOT CONTROLLER FOR HUMAN-ROBOT INTERACTION USING PREDICTIVE ALGORITHMS." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-54609.
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The demand for robots to work in environments together with humans is growing. This calls for new requirements on robots systems, such as the need to be perceived as responsive and accurate in human interactions. This thesis explores the possibility of using AI methods to predict the movement of a human and evaluating if that information can assist a robot with human interactions. The AI methods that were used is a Long Short Term Memory(LSTM) network and an artificial neural network(ANN). Both networks were trained on data from a motion capture dataset and on four different prediction times: 1/2, 1/4, 1/8 and a 1/16 second. The evaluation was performed directly on the dataset to determine the prediction error. The neural networks were also evaluated on a robotic arm in a simulated environment, to show if the prediction methods would be suitable for a real-life system. Both methods show promising results when comparing the prediction error. From the simulated system, it could be concluded that with the LSTM prediction the robotic arm would generally precede the actual position. The results indicate that the methods described in this thesis report could be used as a stepping stone for a human-robot interactive system.
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Collette, Thierry. "Architecture et validation comportementale en VHDL d'un calculateur parallèle dédié à la vision." Phd thesis, Grenoble INPG, 1992. http://tel.archives-ouvertes.fr/tel-00341876.
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Actuellement, l'accélération des opérations de traitement d'images est principalement obtenue par l'utilisation de calculateurs parallèles. De tels processeurs, a flot d'instructions unique et a flots de données multiples (simd), sont développés, mais s'ils s'avèrent efficaces pour les opérations de traitement d'images dites de bas niveau, ou la structure des données reste la même, ils se heurtent a de nombreux problèmes lorsqu'il s'agit des opérations de moyen et de haut niveau. Notamment lors des opérations de moyen niveau, une réorganisation aléatoire des données sur les processeurs doit être effectuée, tache difficilement exécutable sur les structures parallèles synchrones a mémoire distribuée. Le but de cette thèse était d'étendre les capacités d'un calculateur simd, afin qu'il puisse exécuter, efficacement, les opérations de traitement d'images de moyen niveau. L'étude des algorithmes représentatifs de cette classe d'opérations dégage les limites de ce calculateur que des modifications d'architecture permettent d'affranchir. C'est ainsi que Sympatix, le nouveau calculateur SIMD, a été proposé. Afin de le valider, son modèle comportemental décrit en VHDL langage de description de matériel a été élaboré. Grâce a ce modèle, les performances de la nouvelle structure sont ainsi directement mesurées, par simulations d'algorithmes de traitement d'images. L'approche par modélisation VHDL permet, de plus, d'effectuer la conception électronique descendante du système, ce qui, par ailleurs, offre un couplage aise entre les modifications architecturales du système et leur cout électronique. Les résultats obtenus montrent que Sympatix est adapte aux opérations de traitement d'images de bas et de moyen niveau, qu'il est ouvert a un calculateur de haut niveau, et qu'il est capable de supporter d'autres applications de vision. Ce manuscrit présente également, une méthodologie de conception descendante, basée sur le vhdl, et destinée aux architectes de systèmes électroniques
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Demazeau, Yves. "Niveaux de représentation pour la vision par ordinateur : indices d'image et indices de scène." Phd thesis, Grenoble INPG, 1986. http://tel.archives-ouvertes.fr/tel-00322886.
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La première partie analyse les méthodes utilisées dans le domaine, justifie l'existence de différents niveaux de représentation et de traitement de l'information visuelle, puis explicite les cinq niveaux (IMAGE, INDICES D'IMAGE, INDICES DE SCHENE, OBJET et SCHENE) que nous distinguons. La seconde partie décrit, du niveau IMAGE au niveau INDICES DE SCHENE, une expérimentation de l'inférence de formes à partir des contours dans le domaine restreint d'objets solides du monde des blocs. S'appuyant sur les résultats obtenus, la troisième partie expose comment la stéréovision et la couleur s'intègrent au sein des niveaux préconisés, et comment ils permettent d'atteindre le niveau OBJET pour des objets flexibles filiformes. Ces apports sont illustrés par une application au domaine industriel: l'identification et la localisation de fils électriques dans un contexte d'automatisation de la production des ensembles câbles-connecteurs
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Alibay, Manu. "Fusion de données capteurs étendue pour applications vidéo embarquées." Thesis, Paris, ENMP, 2015. http://www.theses.fr/2015ENMP0032/document.
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Le travail réalisé au cours de cette thèse se concentre sur la fusion des données d'une caméra et de capteurs inertiels afin d'effectuer une estimation robuste de mouvement pour des applications vidéos embarquées. Les appareils visés sont principalement les téléphones intelligents et les tablettes. On propose une nouvelle technique d'estimation de mouvement 2D temps réel, qui combine les mesures visuelles et inertielles. L'approche introduite se base sur le RANSAC préemptif, en l'étendant via l'ajout de capteurs inertiels. L'évaluation des modèles de mouvement se fait selon un score hybride, un lagrangien dynamique permettant une adaptation à différentes conditions et types de mouvements. Ces améliorations sont effectuées à faible coût, afin de permettre une implémentation sur plateforme embarquée. L'approche est comparée aux méthodes visuelles et inertielles. Une nouvelle méthode d'odométrie visuelle-inertielle temps réelle est présentée. L'interaction entre les données visuelles et inertielles est maximisée en effectuant la fusion dans de multiples étapes de l'algorithme. A travers des tests conduits sur des séquences acquises avec la vérité terrain, nous montrons que notre approche produit des résultats supérieurs aux techniques classiques de l'état de l'artThis thesis deals with sensor fusion between camera and inertial sensors measurements in order to provide a robust motion estimation algorithm for embedded video applications. The targeted platforms are mainly smartphones and tablets. We present a real-time, 2D online camera motion estimation algorithm combining inertial and visual measurements. The proposed algorithm extends the preemptive RANSAC motion estimation procedure with inertial sensors data, introducing a dynamic lagrangian hybrid scoring of the motion models, to make the approach adaptive to various image and motion contents. All these improvements are made with little computational cost, keeping the complexity of the algorithm low enough for embedded platforms. The approach is compared with pure inertial and pure visual procedures. A novel approach to real-time hybrid monocular visual-inertial odometry for embedded platforms is introduced. The interaction between vision and inertial sensors is maximized by performing fusion at multiple levels of the algorithm. Through tests conducted on sequences with ground-truth data specifically acquired, we show that our method outperforms classical hybrid techniques in ego-motion estimation
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Hallum, Luke Edward Graduate School of Biomedical Engineering Faculty of Engineering UNSW. "Prosthetic vision : Visual modelling, information theory and neural correlates." Publisher:University of New South Wales. Graduate School of Biomedical Engineering, 2008. http://handle.unsw.edu.au/1959.4/41450.
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Electrical stimulation of the retina affected by photoreceptor loss (e.g., cases of retinitis pigmentosa) elicits the perception of luminous spots (so-called phosphenes) in the visual field. This phenomenon, attributed to the relatively high survival rates of neurons comprising the retina's inner layer, serves as the cornerstone of efforts to provide a microelectronic retinal prosthesis -- a device analogous to the cochlear implant. This thesis concerns phosphenes -- their elicitation and modulation, and, in turn, image analysis for use in a prosthesis. This thesis begins with a comparative review of visual modelling of electrical epiretinal stimulation and analogous acoustic modelling of electrical cochlear stimulation. The latter models involve coloured noise played to normal listeners so as to investigate speech processing and electrode design for use in cochlear implants. Subsequently, four experiments (three psychophysical and one numerical), and two statistical analyses, are presented. Intrinsic signal optical imaging in cerebral cortex is canvassed appendically. The first experiment describes a visual tracking task administered to 20 normal observers afforded simulated prosthetic vision. Fixation, saccade, and smooth pursuit, and the effect of practice, were assessed. Further, an image analysis scheme is demonstrated that, compared to existing approaches, assisted fixation and pursuit (but not saccade) accuracy (35.8% and 6.8%, respectively), and required less phosphene array scanning. Subsequently, (numerical) information-theoretic reasoning is provided for the scheme's superiority. This reasoning was then employed to further optimise the scheme (resulting in a filter comprising overlapping Gaussian kernels), and may be readily extended to arbitrary arrangements of many phosphenes. A face recognition study, wherein stimuli comprised either size- or intensity-modulated phosphenes, is then presented. The study involved unpracticed observers (n=85), and showed no 'size' --versus--'intensity' effect. Overall, a 400-phosphene (100-phosphene) image afforded subjects 89.0% (64.0%) correct recognition (two-interval forced-choice paradigm) when five seconds' scanning was allowed. Performance fell (64.5%) when the 400-phosphene image was stabilised on the retina and presented briefly. Scanning was similar in 400- and 100-phosphene tasks. The final chapter presents the statistical effects of sampling and rendering jitter on the phosphene image. These results may generalise to low-resolution imaging systems involving loosely packed pixels.
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Feydt, Austin Pack. "A Higher-Fidelity Approach to Bridging the Simulation-Reality Gap for 3-D Object Classification." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1558355175360648.
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McClure, Kerry S. "The use of object-oriented tools in the development of a pilot's vision simulation program to aid in the conceptual design of aircraft." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-07292009-090340/.
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Discours, Christophe. "Analyse du mouvement par mise en correspondance d'indices visuels." Phd thesis, Grenoble INPG, 1990. http://tel.archives-ouvertes.fr/tel-00338382.
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Nous présentons un système de vision utilisant la mesure du mouvement pour extraire des informations tridimensionnelles. Ce système permet de fournir des indices 3-d a partir d'une séquence d'images. Il s'articule en trois modules qui peuvent fonctionner indépendamment: une technique d'extraction de segments de droite a partir d'une image de contours. La caractéristique principale de cette technique est d'utiliser un balayage simple de l'image. Elle est donc particulièrement destinée a être câblée et fonctionner en synchronisation avec le balayage vidéo; un suivi d'indices performant. Notre système est fonde sur l'utilisation d'un modèle des indices observes et d'un filtre de Kalman; une reconstruction de segments 3-d. Cette reconstruction, utilisant l'étiquetage de segments dans une séquence fourni par le suivi d'indices, est fonde sur l'utilisation des équations de la stereovision
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Tian, Jingduo. "Quantitative performance evaluation of autonomous visual navigation." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/quantitative-performance-evaluation-of-autonomous-visual-navigation(be6349b5-3b38-4ac5-aba2-fc64597fd98a).html.
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Autonomous visual navigation algorithms for ground mobile robotic systems working in unstructured environments have been extensively studied for decades. Among these work, algorithm performance evaluations between different design configurations mainly involve the use of benchmark datasets with a limited number of real-world trails. Such evaluations, however, have difficulties to provide sufficient statistical power for performance quantification. In addition, they are unable to independently assess the algorithm robustness to individual realistic uncertainty sources, including the environment variations and processing errors. This research presents a quantitative approach to performance and robustness evaluation and optimisation of autonomous visual navigation algorithms, using large scale Monte-Carlo analyses. The Monte-Carlo analyses are supported by a simulation environment designed to represent a real-world level of visual information, using the perturbations from realistic visual uncertainties and processing errors. With the proposed evaluation method, a stereo vision based autonomous visual navigation algorithm is designed and iteratively optimised. This algorithm encodes edge-based 3D patterns into a topological map, and use them for the subsequent global localisation and navigation. An evaluation on the performance perturbations from individual uncertainty sources indicates that the stereo match error produces significant limitation for the current system design. Therefore, an optimisation approach is proposed to mitigate such an error. This maximises the Fisher information available in stereo image pairs by manipulating the stereo geometry. Moreover, the simulation environment is further updated in association with the algorithm design, which include the quantitative modelling and simulation of localisation error to the subsequent navigation behaviour. During a long-term Monte-Carlo evaluation and optimisation, the algorithm performance has been significantly improved. Simulation experiments demonstrate that the navigation of a 3-DoF robotic system is achieved in an unstructured environment, while possessing sufficient robustness to realistic visual uncertainty sources and systematic processing errors.
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Entschev, Peter Andreas. "Efficient construction of multi-scale image pyramids for real-time embedded robot vision." Universidade Tecnológica Federal do Paraná, 2013. http://repositorio.utfpr.edu.br/jspui/handle/1/720.
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Detectores de pontos de interesse, ou detectores de keypoints, têm sido de grande interesse para a área de visão robótica embarcada, especialmente aqueles que possuem robustez a variações geométricas, como rotação, transformações afins e mudanças em escala. A detecção de características invariáveis a escala é normalmente realizada com a construção de pirâmides de imagens em multiescala e pela busca exaustiva de extremos no espaço de escala, uma abordagem presente em métodos de reconhecimento de objetos como SIFT e SURF. Esses métodos são capazes de encontrar pontos de interesse bastante robustos, com propriedades adequadas para o reconhecimento de objetos, mas são ao mesmo tempo computacionalmente custosos. Nesse trabalho é apresentado um método eficiente para a construção de pirâmides de imagens em sistemas embarcados, como a plataforma BeagleBoard-xM, de forma similar ao método SIFT. O método aqui apresentado tem como objetivo utilizar técnicas computacionalmente menos custosas e a reutilização de informações previamente processadas de forma eficiente para reduzir a complexidade computacional. Para simplificar o processo de construção de pirâmides, o método utiliza filtros binomiais em substituição aos filtros Gaussianos convencionais utilizados no método SIFT original para calcular múltiplas escalas de uma imagem. Filtros binomiais possuem a vantagem de serem implementáveis utilizando notação ponto-fixo, o que é uma grande vantagem para muitos sistemas embarcados que não possuem suporte nativo a ponto-flutuante. A quantidade de convoluções necessária é reduzida pela reamostragem de escalas já processadas da pirâmide. Após a apresentação do método para construção eficiente de pirâmides, é apresentada uma maneira de implementação eficiente do método em uma plataforma SIMD (Single Instruction, Multiple Data, em português, Instrução Única, Dados Múltiplos) – a plataforma SIMD usada é a extensão ARM Neon disponível no processador ARM Cortex-A8 da BeagleBoard-xM. Plataformas SIMD em geral são muito úteis para aplicações multimídia, onde normalmente é necessário realizar a mesma operação em vários elementos, como pixels em uma imagem, permitindo que múltiplos dados sejam processados com uma única instrução do processador. Entretanto, a extensão Neon no processador Cortex-A8 não suporta operações em ponto-flutuante, tendo o método sido cuidadosamente implementado de forma a superar essa limitação. Por fim, alguns resultados sobre o método aqui proposto e método SIFT original são apresentados, incluindo seu desempenho em tempo de execução e repetibilidade de pontos de interesse detectados. Com uma implementação direta (sem o uso da plataforma SIMD), é mostrado que o método aqui apresentado necessita de aproximadamente 1/4 do tempo necessário para construir a pirâmide do método SIFT original, ao mesmo tempo em que repete até 86% dos pontos de interesse. Com uma abordagem completamente implementada em ponto-fixo (incluindo a vetorização com a plataforma SIMD) a repetibilidade chega a 92% dos pontos de interesse do método SIFT original, porém, reduzindo o tempo de processamento para menos de 3%.Interest point detectors, or keypoint detectors, have been of great interest for embedded robot vision for a long time, especially those which provide robustness against geometrical variations, such as rotation, affine transformations and changes in scale. The detection of scale invariant features is normally done by constructing multi-scale image pyramids and performing an exhaustive search for extrema in the scale space, an approach that is present in object recognition methods such as SIFT and SURF. These methods are able to find very robust interest points with suitable properties for object recognition, but at the same time are computationally expensive. In this work we present an efficient method for the construction of SIFT-like image pyramids in embedded systems such as the BeagleBoard-xM. The method we present here aims at using computationally less expensive techniques and reusing already processed information in an efficient manner in order to reduce the overall computational complexity. To simplify the pyramid building process we use binomial filters instead of conventional Gaussian filters used in the original SIFT method to calculate multiple scales of an image. Binomial filters have the advantage of being able to be implemented by using fixed-point notation, which is a big advantage for many embedded systems that do not provide native floating-point support. We also reduce the amount of convolution operations needed by resampling already processed scales of the pyramid. After presenting our efficient pyramid construction method, we show how to implement it in an efficient manner in an SIMD (Single Instruction, Multiple Data) platform -- the SIMD platform we use is the ARM Neon extension available in the BeagleBoard-xM ARM Cortex-A8 processor. SIMD platforms in general are very useful for multimedia applications, where normally it is necessary to perform the same operation over several elements, such as pixels in images, enabling multiple data to be processed with a single instruction of the processor. However, the Neon extension in the Cortex-A8 processor does not support floating-point operations, so the whole method was carefully implemented to overcome this limitation. Finally, we provide some comparison results regarding the method we propose here and the original SIFT approach, including performance regarding execution time and repeatability of detected keypoints. With a straightforward implementation (without the use of the SIMD platform), we show that our method takes approximately 1/4 of the time taken to build the entire original SIFT pyramid, while repeating up to 86% of the interest points found with the original method. With a complete fixed-point approach (including vectorization within the SIMD platform) we show that repeatability reaches up to 92% of the original SIFT keypoints while reducing the processing time to less than 3%.
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Blum, Richard Alan. "An analog VLSI centroid imager." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/14826.
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Nain, Delphine. "Scale-based decomposable shape representations for medical image segmentation and shape analysis." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-11192006-184858/.
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Thesis (Ph. D.)--Computing, Georgia Institute of Technology, 2007.Aaron Bobick, Committee Chair ; Allen Tannenbaum, Committee Co-Chair ; Greg Turk, Committee Member ; Steven Haker, Committee Member ; W. Eric. L. Grimson, Committee Member.
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Colombet, Florent. "Facteur d'échelle visuelle pour la restitution de la perception de vitesse en simulation de conduite automobile." Phd thesis, Paris, ENSAM, 2010. http://pastel.archives-ouvertes.fr/pastel-00546257.
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Percevoir sa vitesse est une tâche importante que le conducteur doit réaliser constamment pendant la conduite pour contrôler son véhicule. Il apparaît que plusieurs facteurs ont une influence sur la perception de la vitesse : la hauteur du point de vue, le champ de vision, le réalisme de l'environnement, mais aussi le réalisme des restitutions sonores et proprioceptives. Si certains simulateurs de conduite automobile sont suffisamment performants pour restituer le mouvement de façon satisfaisante selon tous ces critères, ce n'est pas forcément le cas de tous. Il en résulte alors une perception de la vitesse souvent sous-estimée, qui se traduit par une vitesse de conduite plus élevée que celle en conduite réelle. La validité perceptive du simulateur de conduite n'est alors plus suffisante pour certaines études de comportement du conducteur. Pour tenter de résoudre ce problème, une technique a récemment vu le jour, consistant à modifier le champ de vision géométrique tout en gardant un champ de vision constant. C'est cette technique, quantifiée par un indice défini comme un facteur d'échelle visuelle, qui est étudiée de façon plus approfondie au cours de cette thèse. Nous avons notamment étudié comment ce facteur d'échelle visuelle influence la perception de la vitesse et avons déterminé la relation linéaire qui existe entre le changement de vitesse perçue et le facteur d'échelle visuelle utilisé. Nous avons ensuite déterminé dans quelle mesure il était possible de modifier dynamiquement ce facteur d'échelle visuelle afin de l'adapter au mieux en fonction des besoins de la simulation. Les expérimentations présentées ici ont toutes été menées sur le simulateur de conduite dynamique SAAM, dont la conception, la réalisation et le réglage ont été effectués dans le cadre de cette thèse.
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Dehos, Julien. "Étude radiométrique d'un système de projection immersive grand-public pour des applications de réalité mixte." Phd thesis, Université du Littoral Côte d'Opale, 2010. http://tel.archives-ouvertes.fr/tel-00598616.
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Le système Catopsys est un système projecteur-miroir-caméra à placer dans une pièce d'habitation quelconque. Il constitue un moyen abordable (coût, installation, utilisation) de réaliser toutes sortes d'applications de réalité mixte immersives. L'objectif de cette thèse est d'étudier et d'optimiser la chaîne de traitement radiométrique mise en oeuvre à travers ce système. Tout d'abord, les perturbations radiométriques de la caméra sont étudiées puis une méthode de correction, applicable au système Catopsys, est mise au point. Ceci permet, de façon relativement fidèle, d'acquérir l'environnement réel et d'estimer les perturbations issues du projecteur et de la pièce. L'influence du projecteur et de la pièce, utilisée comme écran de projection, sur l'image visible par l'utilisateur, est ensuite étudiée. Une méthode de compensation de la projection, permettant de rendre l'image visible plus proche de l'image voulue, est proposée. Après une étude de la géométrie du système Catopsys, des méthodes de simulation d'éclairage spécifiques, dérivées de la méthode de lancer de rayons, sont proposées. Enfin, les possibilités fournies par le système pour des applications de réalité mixte ainsi que leur intégration dans la chaîne de traitement sont étudiées. Les travaux réalisés dans le cadre de cette thèse ont permis de participer à la mise au point du système Catopsys, d'étudier la faisabilité de différentes fonctionnalités et d'en réaliser certaines. Ils ont également donné lieu à la publication de plusieurs papiers (une conférence internationale, une revue nationale, une conférence nationale).
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Dumont, Eric. "Caractérisation, modélisation et simulation des effets visuels du brouillard pour l'usager de la route." Phd thesis, Université René Descartes - Paris V, 2002. http://tel.archives-ouvertes.fr/tel-00164237.
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Sur la route, le brouillard est relativement rare, mais particulièrement meurtrier. Pour améliorer la sécurité des usagers, les solutions passent d'abord par la prévention, la prévision et la détection, mais également par la signalisation, l'éclairage et l'aide à la conduite. Toutefois, la conception de solutions adaptées, susceptibles de compenser la perte de visibilité induite par le brouillard, repose sur la compréhension du phénomène. De plus, l'évaluation de ces solutions en termes de comportement de conduite passe nécessairement par la simulation, étant donnée la quasi-impossibilité des expérimentations en brouillard réel. L'objet de cette étude est de décrire les dégradations induites par le brouillard dans l'environnement visuel du conducteur, en vue de les modéliser et de les reproduire sur simulateur de conduite.Dans la première partie, essentiellement bibliographique, on commence par constater la contradiction entre la complexité et la diversité des propriétés microphysiques et optiques du brouillard d'une part, et l'utilisation courante de la notion de “ distance de visibilité ” pour en décrire les effets perceptifs d'autre part. On montre ensuite que la caractérisation des effets visuels du brouillard passe par une analyse fréquentielle des perturbations induites par la diffusion de la lumière dans la distribution de luminance formant le signal visuel. En vue de maîtriser le recueil des images indispensables à cette analyse, on choisit de faire appel à la synthèse d'images en privilégiant la méthode du tracé de rayons.
Dans la deuxième partie, on commence par décrire la technique de tracé de photons de type Monte-Carlo développée pour simuler la diffusion multiple et anisotrope de la lumière au sein d'un milieu polydispersé tel que le brouillard. Le code ainsi mis au point est ensuite mis en œuvre afin d'étudier les propriétés de la fonction de transfert de modulation d'une couche de brouillard, assimilée à un filtre optique, ce qui nous conduit à définir un opérateur fréquentiel de contraste pour caractériser le halo généré autour du signal transmis par l'énergie lumineuse diffusée. En se basant sur la loi de Koschmieder, on propose finalement un modèle étendu des effets visuels du brouillard – extinction, halo et voiles (atmosphérique et rétro-diffusé) – permettant de prédire les dégradations engendrées par le brouillard dans l'environnement visuel de l'usager de la route en toutes conditions de circulation. On montre également que le modèle proposé est compatible avec une mise en œuvre interactive sur simulateur de conduite.
Le modèle photométrique des effets visuels du brouillard issu de ce travail a dores et déjà fait l'objet d'une validation expérimentale, en collaboration avec des psychologues de la conduite. Il a également été utilisé pour améliorer les outils de simulation de conduite dans le brouillard, en collaboration avec une société spécialisée dans la simulation temps-réel. Il est prévu de mettre en œuvre ces outils pour étudier les performances de l'infrastructure routière en termes de visibilité et de lisibilité par temps de brouillard.
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Falcou, Joël. "Un cluster pour la vision temps réel : architecture, outils et application." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2006. http://tel.archives-ouvertes.fr/tel-00717444.
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Cette thèse propose une solution logicielle au problème du développement et de l'exécution en temps réel d'applications de vision sur des machines de type cluster. Pour cela, avons développé deux bibliothèques utilisant des techniques d'évaluation partielle et de méta-programmation template qui permettent de programmer ces machines en s'attachant à rendre accessible les modèles de programmation parallèles à des développeurs issus de la communauté Vision pour qui ces problématiques ne sont pas triviales, tout en conservant des performances élevées. Ces deux bibliothèques : EVE, qui prend en charge la gestion du parallélisme SIMD, et QUAF, qui propose un modèle de programmation à base de squelettes algorithmiques pour la programmation sur machines MIMD, ont été validées par deux applications de vision de complexité réaliste, une reconstruction 3D et un suivi de piéton par filtrage particulaire, développées et exécutées sur un cluster dédié à la vision artificielle
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Ekström, Per, and Elisabeth Eriksson. "REDUNDANT FIRMWARE TEST SETUP IN SIMULATION AND HARDWARE: A FEASIBILITY STUDY." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-40057.
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A reliable embedded real-time system has many requirements to fulfil. It must meet target deadlines in a number of situations, most of them in a situation that puts heavy stress on the system. To meet these demands, numerous tests have been created which test the hardware for any possible errors the developers might think of, in order to maximise system reliability and stability. These tests will take a lot of time to execute, and as system complexity grows, more tests are introduced leading to even longer testing times. In this thesis, a method to reduce the testing time of the software and, to a lesser extent, the hardware is examined. By using the full system simulator Simics, an existing industry system from ABB was integrated and tests were performed. A proof of concept test suite for automatic redundancy tests was also implemented. By looking at the test results, it was concluded that the method shows promise. However, problems with the average latency and performance troubles with Simics shows that more work must be put into this research before the system can be run at full speed.
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Klaser, Alexander. "Apprentissage pour la reconnaissance d'actions humaines en vidéo." Phd thesis, Grenoble, 2010. http://tel.archives-ouvertes.fr/tel-00514814.
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Cette thèse s'intéresse à la reconnaissance des actions humaines dans des données vidéo réalistes, tels que les films. À cette fin, nous développons des algorithmes d'extraction de caractéristiques visuelles pour la classification et la localisation d'actions.
Dans une première partie, nous étudions des approches basées sur les sacs-de-mots pour la classification d'action. Dans le cas de vidéo réalistes, certains travaux récents qui utilisent le modèle sac-de-mots pour la représentation d'actions ont montré des résultats prometteurs. Par conséquent, nous effectuons une comparaison approfondie des méthodes existantes pour la détection et la description des caractéristiques locales. Ensuite, nous proposons deux nouvelles approches pour la descriptions des caractéristiques locales en vidéo. La première méthode étend le concept d'histogrammes sur les orientations de gradient dans le domaine spatio-temporel. La seconde méthode est basée sur des trajectoires de points d'intérêt détectés spatialement. Les deux descripteurs sont évalués avec une représentation par sac-de-mots et montrent une amélioration par rapport à l'état de l'art pour la classification d'actions.
Dans une seconde partie, nous examinons comment la détection de personnes peut contribuer à la reconnaissance d'actions. Tout d'abord, nous développons une approche qui combine la détection de personnes avec une représentation sac-de-mots. La performance est évaluée pour la classification d'actions à plusieurs niveaux d'échelle spatiale. Ensuite, nous explorons la localisation spatio-temporelle des actions humaines dans les films. Nous étendons une approche de suivi de personnes pour des vidéos réalistes. En outre, nous développons une représentation d'actions qui est adaptée aux détections de personnes. Nos expériences suggèrent que la détection de personnes améliore significativement la localisation d'actions. De plus, notre système montre une grande amélioration par rapport à l'état de l'art actuel.
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Elbadramany, Iman K. "Towards calibration of optical flow of crowd videos using observed trajectories." Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4889.
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The Particle Image Velocimetry optical flow algorithm had better correspondence with the velocity vectors of manually tracked crowd members than results obtained using the Lukas-Kanade method. Here, also, it was found that 40x40 pixel cells were better than 15x15. A second attempt at quantifying the correlation between optical flow and actual crowd member velocities was studied using simulations. Two processes were researched, which utilized geometrical correction of the perspective distortion of the crowd videos. One process geometrically corrects the video, and then obtains optical flow data. The other obtains optical flow data from video, and then geometrically corrects the data. The results indicate that the first process worked better. Correlation was calculated between sets of data obtained from the average of twenty frames. This was found to be higher than calculating correlations between the velocities of cells in each pair of frames. An experiment was carried out to predict crowd tracks using optical flow and a calculated parameter, beta, seems to give promising results.; The need exists for finding a quantitative method for validating crowd simulations. One approach is to use optical flow of videos of real crowds to obtain velocities that can be used for comparison to simulations. Optical flow, in turn, needs to be calibrated to be useful. It is essential to show that optical flow velocities obtained from crowd videos can be mapped into the spatially averaged velocities of the observed trajectories of crowd members, and to quantify the extent of the correlation of the results. This research investigates methods to uncover the best conditions for a good correlation between optical flow and the average motion of individuals in crowd videos, with the aim that this will help in the quantitative validation of simulations. The first approach was to use a simple linear proportionality relation, with a single coefficient, alpha, between velocity vector of the optical flow and observed velocity of crowd members in a video or simulation. Since there are many variables that affect alpha, an attempt was made to find the best possible conditions for determining alpha, by varying experimental and optical flow settings. The measure of a good alpha was chosen to be that alpha does not vary excessively over a number of video frames. Best conditions of low coefficient of variation of alpha using the Lucas-Kanade optical flow algorithm were found to be when a larger aperture of 15x15 pixels was used, combined with a smaller threshold. Adequate results were found at cell size 40x40 pixels; the improvement in detecting details when smaller cells are used did not reduce the variability of alpha, and required much more computing power. Reduction in variability of alpha can be obtained by spreading the tracked location of a crowd member from a pixel into a rectangle.ID: 030423090; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2011.; Includes bibliographical references (p. 104-108).
M.S.
Masters
Sciences
Modeling and Simulation
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Mebrek, Fateh. "Outils d'aide à la décision basés sur la simulation pour la logistique hospitalière, application à un nouvel hôpital." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2008. http://tel.archives-ouvertes.fr/tel-00731433.
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De nos jours les entreprises dans notre cas les systèmes hospitaliers, ont besoin de modéliser leur organisation, afin d'analyser leur fonctionnement, de détecter les dysfonctionnements et d'inventorier les flux internes et ceux échangés avec l'environnement. La modélisation étant un outil d'aide à la décision permettant d'éviter des investissements inconsidérés. Cette thèse décrit une modélisation et une simulation d'un hôpital moderne du système hospitalier français. Une méthodologie de modélisation ASCI (Analyse, Spécification, Conception et Implémentation) est utilisée pour ce système. Le processus de modélisation proposé fournit des modèles (modèle de connaissances, modèles d'action, modèles de résultats) dont l'évaluation permet de dimensionner le système et d'obtenir ses performances. Dans ce contexte s'inscrit ce travail de recherche, qui consiste à développer et utiliser la méthodologie de modélisation ASCI qui a été développé au sein du laboratoire LIMOS de Clermont-Ferrand pour la classe de systèmes de production et que nous adaptons aux systèmes hospitaliers.
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Hunter, David W. "Synthesis of facial ageing transforms using three-dimensional morphable models." Thesis, St Andrews, 2009. http://hdl.handle.net/10023/763.
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Nett, Ryan. "Dataset and Evaluation of Self-Supervised Learning for Panoramic Depth Estimation." DigitalCommons@CalPoly, 2020. https://digitalcommons.calpoly.edu/theses/2234.
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Depth detection is a very common computer vision problem. It shows up primarily in robotics, automation, or 3D visualization domains, as it is essential for converting images to point clouds. One of the poster child applications is self driving cars. Currently, the best methods for depth detection are either very expensive, like LIDAR, or require precise calibration, like stereo cameras. These costs have given rise to attempts to detect depth from a monocular camera (a single camera). While this is possible, it is harder than LIDAR or stereo methods since depth can't be measured from monocular images, it has to be inferred. A good example is covering one eye: you still have some idea how far away things are, but it's not exact. Neural networks are a natural fit for this. Here, we build on previous neural network methods by applying a recent state of the art model to panoramic images in addition to pinhole ones and performing a comparative evaluation. First, we create a simulated depth detection dataset that lends itself to panoramic comparisons and contains pre-made cylindrical and spherical panoramas. We then modify monodepth2 to support cylindrical and cubemap panoramas, incorporating current best practices for depth detection on those panorama types, and evaluate its performance for each type of image using our dataset. We also consider the resources used in training and other qualitative factors.
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Chanceaux, Myriam. "Modélisation cognitive computationnelle de trajets oculomoteurs lors d'une tâche de recherche d'information." Phd thesis, Université Joseph Fourier (Grenoble), 2009. http://tel.archives-ouvertes.fr/tel-00430624.
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Ce travail de thèse étudie la combinaison des processus visuels et sémantiques dans le traitement d'interfaces textuelles, comme des pages web. La méthodologie employée est la simulation de modèles cognitifs, une approche visant à concevoir un programme informatique s'inspirant de modèles cognitifs théoriques et reproduisant au mieux le comportement humain. Notre modèle simule les trajets oculomoteurs d'un utilisateur moyen lors d'une recherche d'information. Les processus mis en jeu dans ce type de tâche sont modélisés afin de reproduire les mouvements oculaires humains enregistrés lors de différentes expérimentations. Aux modèles des processus visuels et sémantiques est ajouté un modèle des processus mnésiques sous-jacents à la recherche d'information. Pour la partie visuelle, le modèle s'inspire des cartes de saillance qui prédisent les zones de l'écran susceptibles d'attirer l'attention, en fonction des informations à bas niveau (couleur, orientation et contraste), ainsi que des propriétés physiologiques de l'œil humain. Pour la partie sémantique, la technique de mesure de similarités sémantiques entre le but de l'utilisateur et les différentes parties de la page employée est LSA (Latent Semantic Analysis) (Landauer, 1998). Pour la partie mnésique, le mécanisme d'Inhibition of Return (Klein, 1999) et le Variable Memory Model (Horowitz, 2006) sont utilisés. Le travail de thèse intègre trois parties: conception d'un modèle théorique d'interaction, conception de l'outil de simulation, et mise en place d'expérimentations psychophysiques de relevés oculométriques permettant de valider et d'affiner le modèle proposé.
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Delingette, Hervé. "Modélisation, déformation et reconnaissance d'objets tridimensionnels à l'aide de maillages simplexes." Phd thesis, Ecole Centrale Paris, 1994. http://tel.archives-ouvertes.fr/tel-00632191.
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Dans cette thèse, une représentation originale d'objets tridimensionnels est introduite: les maillages simplexes. un k-maillage simplexe est un maillage ou chaque sommet est connecte à k + 1 sommets voisins. Ainsi un contour est représenté par un 1-maillage simplexe et une surface tridimensionnelle par un 2-maillage simplexe. La structure d'un maillage simplexe est duale de celle des triangulations. Plusieurs propriétés topologiques et géométriques originales rendent l'utilisation des maillages simplexes particulièrement bien adaptée à la représentation de surfaces déformables. Nous introduisons la notion d'angle simplexe, de courbure moyenne discrète et de paramètre métrique à chaque sommet du maillage. La propriété géométrique essentielle des maillages simplexes est la possibilité de représenter localement la forme d'un k-maillage en un sommet à l'aide de (k + 1) quantités adimensionnées. Les maillages simplexes déformables sont alors utilisés dans un système de modélisation d'objets tridimensionnels. En présence d'images volumiques ou de profondeur, un maillage simplexe est déformé sous l'action de forces régularisantes et de forces externes. Les maillages simplexes sont adaptatifs à plusieurs titres. D'une part, les sommets se concentrent aux endroits de fortes courbure et d'autre part, le maillage peut être raffiné ou décimé en fonction de la proximité des sommets aux données. Enfin, l'utilisation de maillages simplexes sphériques quasi-réguliers permet la reconnaissance de forme d'objets tridimensionnels, même en présence d'occultations. La forme d'un objet est alors représentée par l'ensemble des valeurs des angles simplexes du maillage simplexe déformé, projeté sur le maillage sphérique originel. La forme de deux objets est comparée par l'intermédiaire de leur image simplexe (simplex angle image)
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Klaser, Rafael Luiz. "Navegação de veículos autônomos em ambientes externos não estruturados baseada em visão computacional." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-22092014-095209/.
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Este trabalho apresenta um sistema de navegação autônoma para veículos terrestres com foco em ambientes não estruturados, tendo como principal meta aplicações em campos abertos com vegetação esparsa e em cenário agrícola. É aplicada visão computacional como sistema de percepção principal utilizando uma câmera estéreo em um veículo com modelo cinemático de Ackermann. A navegação é executada de forma deliberativa por um planejador baseado em malha de estados sobre um mapa de custos e localização por odometria e GPS. O mapa de custos é obtido através de um modelo de ocupação probabilístico desenvolvido fazendo uso de uma OctoMap. É descrito um modelo sensorial para atualizar esta OctoMap a partir da informação espacial proveniente de nuvens de pontos obtidas a partir do método de visão estéreo. Os pontos são segmentados e filtrados levando em consideração os ruídos inerentes da aquisição de imagens e do processo de cálculo de disparidade para obter a distância dos pontos. Os testes foram executados em ambiente de simulação, permitindo a replicação e repetição dos experimentos. A modelagem do veículo foi descrita para o simulador físico Gazebo de acordo com a plataforma real CaRINA I (veículo elétrico automatizado do LRM-ICMC/USP), levando-se em consideração o modelo cinemático e as limitações deste veículo. O desenvolvimento foi baseado no ROS (Robot Operating System) sendo utilizada a arquitetura básica de navegação deste framework a partir da customização dos seus componentes. Foi executada a validação do sistema no ambiente real em cenários com terreno irregular e obstáculos diversos. O sistema apresentou um desempenho satisfatório tendo em vista a utilização de uma abordagem baseada em apenas uma câmera estéreo. Nesta dissertação são apresentados os principais componentes de um sistema de navegação autônoma e as etapas necessárias para a sua concepção, assim como resultados de experimentos simulados e com o uso de um veículo autônomo realThis work presents a system for autonomous vehicle navigation focusing on unstructured environments, with the primary goal applications in open fields with sparse vegetation, unstructured environments and agricultural scenario. Computer vision is applied as the main perception system using a stereo camera in a car-like vehicle with Ackermann kinematic model. Navigation is performed deliberatively using a path planner based on a lattice state space over a cost map with localization by odometry and GPS. The cost map is obtained through a probabilistic occupation model developed making use of an OctoMap. It is described a sensor model to update the spatial occupancy information of the OctoMap from a point cloud obtained by stereo vision. The points are segmented and filtered taking into account the noise inherent in the image acquisition and calculation of disparity to obtain the distance from points. Tests are performed in simulation, allowing replication and repetition of experiments. The modeling of the vehicle is described to be used in the Gazebo physics simulator in accordance with the real platform CaRINA I (LRM-ICMC/USP automated electrical vehicle) taking into account the kinematic model and the limitations of this vehicle. The development is based on ROS (Robot Operating System) and its basic navigation architecture is customized. System validation is performed on real environment in scenarios with different obstacles and uneven terrain. The system shows satisfactory performance considering a simple configuration and an approach based on only one stereo camera. This dissertation presents the main components of an autonomous navigation system and the necessary steps for its conception as well as results of experiments in simulated and using a real autonomous vehicle
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Lagová, Lenka. "Rozšířená realita nad obrazem ze stacionární kamery." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2015. http://www.nusl.cz/ntk/nusl-264953.
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This thesis deals with the issue of creating applications of augmented reality. There are described types of augmented reality, problems associated with developing of applications of this kind. Also there is description of method for detection of moving objects from the record of stationary camera. The thesis deals with camera calibration using knowledge of scene geometry. Scene editor for scene geometry estimation is included in this work. Augmented reality is represented by physical simulations, where object from virtual reality interacts with detected objects and with objects defined in scene editor.
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Gorges, Sébastien. "Vers un système de navigation 3D en neuroradiologie interventionnelle." Phd thesis, Université Henri Poincaré - Nancy I, 2007. http://tel.archives-ouvertes.fr/tel-00165960.
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En neuroradiologie interventionnelle, la machine d'angiographie RX est le moyen d'imagerie par excellence pour guider le médecin dans l'accomplissement de songeste thérapeutique. Cette machine permet l'acquisition d'une image 3D montrant les artères du patient (ou 3DXA). Cependant, le contrôle visuel du déploiement des
outils (guide, cathéter...) est effectué en 2D avec une image temps réel (ou fluoroscopie). Cette thèse a pour ambition de contribuer à l'amélioration des techniqu
es de guidage en proposant des outils permettant une utilisation de l?image 3D durant le traitement.
Les images étant acquises avec la même machine d'angiographie, nous avons consacré une partie de notre travail au développement de méthodes fiables de calibrage de
la chaîne image portée par l'arceau rotatif de la machine. Le but était de comprendre si l'arceau se déformait ou non sous l'influence de son poids.
Tirant parti du fait que les images sont acquises avec la même machine, nous avons ensuite proposé une méthode de recalage 3D2D entre l'image 3DXA et la fluorosc
opie. Cette méthode exploite les capteurs de position du système et incorpore les déformations subies par le système.
Suite à ces travaux, un système permettant la fusion de l'image 3DXA avec la fluoroscopie a été développé en collaboration avec GE Healthcare et évalué au CHU de Nanc
y pour le traitement des anévrismes cérébraux.
Enfin, un nouveau système doté de deux chaînes images (ou système bi-plan) a été installé à Nancy durant notre thèse. Après avoir développé une méthode de détection 2D du g
uide dans les images fluoroscopiques, nous avons initié une première étude de la reconstruction 3D du guide à partir des images bi-plan.
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Huguet, Frédéric. "Modélisation et calcul du flot de scène stéréoscopique par une méthode variationnelle." Phd thesis, Université Joseph Fourier (Grenoble), 2009. http://tel.archives-ouvertes.fr/tel-00421958.
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En vision par ordinateur, le flot de scène représente le déplacement des points d'une surface située dans une scène 3D quelconque, entre deux instants consécutifs. Il s'agit donc d'un champ vectoriel 3D. Celui-ci est particulièrement utile dans l'analyse des déformations d'une surface quelconque, observée par un système d'au moins deux caméras. Cette thèse traite de l'estimation du flot de scène et d'une application dans le domaine de la géophysique. Elle s'est déroulée dans le cadre de l'ACI GEOLSTEREO, en collaboration étroite avec le laboratoire Geosciences Azur, situé à Sophia Antipolis (06, UMR 6526 - CNRS - UNSA - UPMC- IRD).
Nous proposons d'estimer le flot de scène en couplant l'évaluation du flot optique dans les séquences d'images associées à chaque caméra, à l'estimation de la correspondance stéréo dense entre les images. De plus, notre approche évalue, en même temps que le flot de scène, les occultations à la fois en flot optique et en stéréo. Nous obtenons au final un système d'EDP couplant le flot optique et la stéréo, que nous résolvons numériquement à l'aide d'un algorithme multirésolution original.
Alors que les précédentes méthodes variationnelles estimaient la reconstrution 3D au temps $t$ et le flot de scène séparément, notre méthode estime les deux simultanément. Nous présentons des résultats numériques sur des séquences synthétiques avec leur vérité terrain, et nous comparons également la précision du flot de scène projeté dans une caméra avec une méthode récente et performante d'estimation variationnelle du flot optique. Des résultats sont présentés sur une séquence stéréo réelle, se rapportant à un mouvement non rigide et à de larges discontinuités.
Enfin, nous présentons l'approche originale de modélisation physique 3D utilisée au laboratoire Geosciences Azur. Nous décrivons la mise en place du dispositif stéréoscopique associé, ainsi que le déroulement de l'expérience. Des résultats de reconstruction 3D, d'estimation du flot de scène, et de suivi de la déformation d'une surface sont montrés dans le chapitre 4 de la thèse.
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Fiorentini, Davide. "Design of a Cartesian Robot for Agro-Food Applications." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Find full textAbstract:
Nella tesi si affronta il problema della progettazione di un sistema meccatronico fortemente automatizzato per applicazioni agricole. In particolare il progetto è rivolto alla costruzione di una macchina per l’attività di raccolta automatizzata di teste di broccoli disposte in filari presenti in campo coltivato.
Il fine dello studio, tramite l’applicazione su un vegetale specifico, è l’introduzione di tecnologie di uso ormai comune nel campo industriale in un settore tradizionalmente poco sensibile all’innovazione come quello agricolo. La progettazione deve quindi tenere conto di diverse problematiche di natura differente a quelle tipicamente industriali ed adoperare opportuni accorgimenti.
L’ideazione di un sistema essenzialmente completo e funzionale, con relativa simulazione di un tipico ciclo di lavoro, si presta successivamente ad ulteriori valutazioni non esclusivamente tecniche ma anche di tipo economico.
Dopo un’analisi generale dello scenario, si è trovato idoneo l’utilizzo di un robot cartesiano montato sopra una macchina agricola guidata da un operatore. Viene concretizzato il disegno ed il dimensionamento delle varie componenti meccaniche, compreso il manipolatore.
In seguito è creato un modello matematico del sistema fisico utile a simulare il funzionamento della macchina. Particolare attenzione è data al controllo del robot in quanto risultante essere la parte più critica del sistema. E’ inoltre fornito il controllo temporizzato delle varie azioni.
Infine si è effettuata una simulazione al calcolatore di un tipico ciclo di raccolta su una singola testa broccolo. Il vegetale, riconosciuto dalla macchina, viene raccolto secondo una sequenza di azioni sincronizzate tra loro e depositato in un punto specifico nel raggio di azione del robot. Sono inoltre forniti elementi sugli aspetti simulativi e sull’integrazione tra varie componenti del sistema complesso.
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Baujard, Olivier. "Conception d'un environnement de développement pour la résolution de problèmes : apport de l'intelligence artificielle distribuée et application à la vision." Phd thesis, Grenoble 1, 1992. http://tel.archives-ouvertes.fr/tel-00341607.
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L'objectif de cette thèse a été de concevoir un environnement de développement pour la resolution de problèmes, s'inspirant des langages a objets et de l'intelligence artificielle distribuée. Un environnement de programmation multi-agents a été conçu dans ce cadre. Cet environnement (maps) est fonde sur la distinction de deux classes d'agents, dédiées a la modélisation et a l'exploitation des connaissances figuratives (agent ks ou knowledge server) et des connaissances opératoires (agent kp ou knowledge processor). Ces classes peuvent alors etre spécialisées a l'aide d'un langage de programmation dedie. Une première version de cet environnement nous a permis de valider ces concepts de base, par la conception d'applications, en vision par ordinateur (système kiss), en diagnostic biomédical (système kids), en compréhension de la parole et en acquisition des connaissances. Le système kiss, décrit dans cette thèse, a été conçu pour manipuler les connaissances introduites par les phases d'analyse de bas niveau, de niveau intermédiaire et de haut niveau, dans une approche de type coopération région/contour. Dans notre approche multi-agents, ces connaissances sont distribuées au sein d'agents ks et kp, formant un réseau. Plusieurs améliorations ont été envisagées pour pallier un certain nombre de faiblesses de cet environnement et le rapprocher des plates-formes de conception en intelligence artificielle distribuée. Des améliorations fonctionnelles concernent l'introduction d'un mode d'exécution parallèle. Ces améliorations ont conduit a la définition d'un nouvel environnement. Des améliorations structurelles, encore a l'étude, concernent la définition d'agents hétérogènes et une structuration en couche des agents
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Kuiaski, José Rosa. "Segmentação de movimento por fluxo ótico." Universidade Tecnológica Federal do Paraná, 2012. http://repositorio.utfpr.edu.br/jspui/handle/1/513.
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A percepção de movimento é uma característica essencial à sobrevivência de diversas espécies. Na natureza, é através do movimento que uma presa percebe a chegada de um predador e decide em que direção deve fugir, bem como o predador detecta a presença de uma presa e decide para onde atacar. O Sistema Visual Humano é mais sensível a movimento do que a imagens estáticas, sendo capaz de separar as informações de movimento originadas pela movimentação própria das informações de movimento de objetos animados no ambiente. A Teoria Ecológica de Gibson (1979) provê uma base para o entendimento de como esse processo de percepção ocorre e estende-se com o conceito do que chamamos de campo vetorial de Fluxo Ótico, através do qual se representa computacionalmente o movimento. O objetivo principal deste trabalho é procurar reproduzir computacionalmente esse comportamento, para possíveis aplicações em navegação autônoma e processamento de vídeo com movimentação desconhecida. Para isso, vale-se das técnicas de estimação de Fluxo Ótico presentes na literatura, tais como as propostas por Lucas e Kanade (1981) e Farneback (1994). Em primeiro momento, avalia-se a possibilidade de utilização de uma técnica estatística de separação cega de fontes, a chamada Análise de Componentes Independentes, tomando como base o trabalho de Bell e Sejnowski (1997), na qual se mostra que tal análise aplicada em imagens fornece filtros de bordas. Depois, avalia-se a utilização do Foco de Expansão para movimentos translacionais. Resultados experimentais demonstram uma maior viabilidade da abordagem por Foco de Expansão.Motion Perception is an essential feature for the survival of several species. In nature, it is through motion that a prey perceives the predator and is able to decide which direction to escape, and the predator detects the presence of a prey and decides where to attack. The Human Visual System is more sensitive to motion than to static imagery, and it is able to separate motion information due to egomotion from that due to an animated object in the environment. The Ecological Theory of Gibson (1979) provides a basis for understanding how this processes of perception occurs, and leads to the concept of what we call the vector field of Optical Flow, through which computational motion is represented. The main objective of this work is to try to reproduce computationally this behaviour, for possible applications in autonomous navigation and video processing with unknown self-motion. For this, we use some Optical Flow estimation techniques, as those proposed by Lucas and Kanade (1981) and Farneback (1994). At first, we assess the possibility of using a statistical technique of blind source separation, the so-called Independent Component Analysis, based on the work of Bell and Sejnowski (1997), which demonstrates that this technique, when applied to imagery, provides edge filters. Then, we assess the use of the Focus of Expansion to translational motion. Experimental results show the second approach, using the Focus of Expansion, is more viable than through Independent Component Analysis.
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Chevallier, Sylvain. "Implémentation d'un système préattentionnel avec des neurones impulsionnels." Phd thesis, Université Paris Sud - Paris XI, 2009. http://tel.archives-ouvertes.fr/tel-00472849.
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Les neurones impulsionnels prennent en compte une caractéristique fondamentale des neurones biologiques : la capacité d'encoder l'information sous forme d'événements discrets. Nous nous sommes intéressés à l'apport de ce type de modèles dans le cadre de la vision artificielle, dont les contraintes nous ont orienté vers le choix de modèles simples, adaptés à la rapidité de traitement requise. Nous décrivons une architecture de réseaux pour encoder et extraire des saillances utilisant la discrétisation induite par les neurones impulsionnels. La carte de saillances est obtenue à partir de la combinaison, spatiale et temporelle, de différentes cartes de modalités visuelles (contrastes, orientations et couleurs) à différentes échelles spatiales. Nous proposons une méthode de filtrage neuronal pour construire les cartes de modalité visuelle. Cette méthode réalise le filtrage de façon graduelle : plus le temps de traitement alloué à l'algorithme est important, plus le résultat est proche de celui obtenu avec un filtrage par convolution. L'architecture proposée donne en sortie les saillances triées temporellement dans l'ordre de leur importance. Nous avons placé en aval de cette architecture un autre réseau de neurones impulsionnels, s'inspirant des champs neuronaux, qui permet de sélectionner la zone la plus saillante et de maintenir une activité constante sur cette zone. Les résultats expérimentaux montrent que l'architecture proposée est capable d'extraire des saillances dans une séquence d'images, de sélectionner la saillance la plus importante et de maintenir la focalisation sur cette saillance, même dans un contexte bruité ou quand la saillance se déplace.
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Reza, Hasnain. "Detection, location, and trajectory tracing of moving objects in the real world two-dimensional images." Ohio : Ohio University, 1988. http://www.ohiolink.edu/etd/view.cgi?ohiou1182869492.
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