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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

UAV Navigation and Radar Odometry

Quist, Eric Blaine 01 March 2015 (has links) (PDF)
Prior to the wide deployment of robotic systems, they must be able to navigate autonomously. These systems cannot rely on good weather or daytime navigation and they must also be able to navigate in unknown environments. All of this must take place without human interaction. A majority of modern autonomous systems rely on GPS for position estimation. While GPS solutions are readily available, GPS is often lost and may even be jammed. To this end, a significant amount of research has focused on GPS-denied navigation. Many GPS-denied solutions rely on known environmental features for navigation. Others use vision sensors, which often perform poorly at high altitudes and are limited in poor weather. In contrast, radar systems accurately measure range at high and low altitudes. Additionally, these systems remain unaffected by inclimate weather. This dissertation develops the use of radar odometry for GPS-denied navigation. Using the range progression of unknown environmental features, the aircraft's motion is estimated. Results are presented for both simulated and real radar data. In Chapter 2 a greedy radar odometry algorithm is presented. It uses the Hough transform to identify the range progression of ground point-scatterers. A global nearest neighbor approach is implemented to perform data association. Assuming a piece-wise constant heading assumption, as the aircraft passes pairs of scatterers, the location of the scatterers are triangulated, and the motion of the aircraft is estimated. Real flight data is used to validate the approach. Simulated flight data explores the robustness of the approach when the heading assumption is violated. Chapter 3 explores a more robust radar odometry technique, where the relatively constant heading assumption is removed. This chapter uses the recursive-random sample consensus (R-RANSAC) Algorithm to identify, associate, and track the point scatterers. Using the measured ranges to the tracked scatterers, an extended Kalman filter (EKF) iteratively estimates the aircraft's position in addition to the relative locations of each reflector. Real flight data is used to validate the accuracy of this approach. Chapter 4 performs observability analysis of a range-only sensor. An observable, radar odometry approach is proposed. It improves the previous approaches by adding a more robust R-RANSAC above ground level (AGL) tracking algorithm to further improve the navigational accuracy. Real flight results are presented, comparing this approach to the techniques presented in previous chapters.
32

Automated evaluation of retinal pigment epithelium disease area in eyes with age-related macular degeneration / 加齢黄斑変性の眼における網膜色素上皮病変面積自動評価

Motozawa, Naohiro 23 March 2022 (has links)
京都大学 / 新制・課程博士 / 博士(医学) / 甲第23813号 / 医博第4859号 / 新制||医||1059(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 中本 裕士, 教授 花川 隆, 教授 大森 孝一 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
33

Image Superresolution through a Network of Wireless Cameras

Directo, Marc 03 1900 (has links)
This thesis outlines a multiple-camera wireless image superresolution system which uses off-the-shelf components. The system presented demonstrates the reconstruction of a high-resolution image from multiple low-resolution images acquired from different wireless camera nodes. Each camera node participating in the system consists of a dedicated camera for image acquisition as well as a Bluetooth USB communications card for wireless transmission of data. Low-resolution images are captured at these nodes and are transmitted to the central vision server, where they are processed and registered onto a common projective plane. The registration process is arrived at through the RANdom SAmple Consensus (RANSAC) algorithm. Once the set of low-resolution images has been registered, a single high-resolution image is reconstructed. The super-resolution process used to obtain the high-resolution output is the Projection Onto Convex Sets (POCS) technique. Reconstruction results are presented. / Thesis / Master of Applied Science (MASc)
34

Integration of a Complete Detect and Avoid System for Small Unmanned Aircraft Systems

Wikle, Jared Kevin 01 May 2017 (has links)
For unmanned aircraft systems to gain full access to the National Airspace System (NAS), they must have the capability to detect and avoid other aircraft. This research focuses on the development of a detect-and-avoid (DAA) system for small unmanned aircraft systems. To safely avoid another aircraft, an unmanned aircraft must detect the intruder aircraft with ample time and distance. Two analytical methods for finding the minimum detection range needed are described. The first method, time-based geometric velocity vectors (TGVV), includes the bank-angle dynamics of the ownship while the second, geometric velocity vectors (GVV), assumes an instantaneous bank-angle maneuver. The solution using the first method must be found numerically, while the second has a closed-form analytical solution. These methods are compared to two existing methods. Results show the time-based geometric velocity vectors approach is precise, and the geometric velocity vectors approach is a good approximation under many conditions. The DAA problem requires the use of a robust target detection and tracking algorithm for tracking multiple maneuvering aircraft in the presence of noisy, cluttered, and missed measurements. Additionally these algorithms needs to be able to detect overtaking intruders, which has been resolved by using multiple radar sensors around the aircraft. To achieve these goals the formulation of a nonlinear extension to R-RANSAC has been performed, known as extended recursive-RANSAC (ER-RANSAC). The primary modifications needed for this ER-RANSAC implementation include the use of an EKF, nonlinear inlier functions, and the Gauss-Newton method for model hypothesis and generation. A fully functional DAA system includes target detection and tracking, collision detection, and collision avoidance. In this research we demonstrate the integration of each of the DAA-system subcomponents into fully functional simulation and hardware implementations using a ground-based radar setup. This integration resulted in various modifications of the radar DSP, collision detection, and collision avoidance algorithms, to improve the performance of the fully integrated DAA system. Using these subcomponents we present flight results of a complete ground-based radar DAA system, using actual radar hardware.
35

Application des techniques de numérisation tridimensionnelle au contrôle de process de pièces de forge / Application of 3D scanning techniques to the process control of forged parts

Bokhabrine, Youssef 11 October 2010 (has links)
L’objectif de ces travaux de thèse est la conception et le développement d’un système de caractérisation tridimensionnelle de pièces forgées de grande dimension portées à haute température. Les travaux se basent sur de nombreuses thématiques telles que l’acquisition tridimensionnelle, l’extraction, la segmentation et le recalage de primitives 3D. Nous présentons tout d’abord les limites des systèmes de caractérisation de pièces forgées cités dans la littérature. Dans la deuxième partie, nous présentons la réalisation du système de caractérisation de pièces forgées, constitué de deux scanners temps de vol (TOF). Nous présentons également le simulateur de numérisation par scanner TOF qui nous permet de nous affranchir des contraintes industrielles (temps, difficulté de manœuvres) pour positionner les deux scanners. La troisième partie est consacrée à l’extraction des primitives 3D. Nous avons traité deux types de primitives : viroles et sphères avec deux approches différentes : méthode supervisée et méthode automatique. La première approche basée sur une méthode de croissance de région et de contour actif, permet d’extraire des formes extrudées complexes. Des problèmes d’ergonomie du système nous ont conduits à développer une deuxième approche, basée sur l’image de Gauss et l’extraction d’ellipse, qui permet l’extraction automatique de formes cylindriques ovales ou circulaires. Nous présentons également quatre méthodes d’extraction automatique de sphères basées sur des approches heuristiques : RANSAC (RANdom SAmple Consensus), algorithme génétique et algorithme génétique par niche. Dans la quatrième partie, nous étudions les différentes approches de recalage de données 3D traitées : le calibrage basé sur les cibles artificielles et le recalage fin basé sur l’algorithme ICP. Pour conclure, nous présentons la réalisation d’un système complet de caractérisation tridimensionnelle de pièces forgées de grande dimension. Ensuite, nous comparons les performances et les limites de ce système avec les systèmes de caractérisation cités dans la littérature. / The main objective of this Phd project is to conceive a machine vision system for hot cylindrical metallic shells diameters measurement during forging process. The manuscript is structured by developing in the first chapter the state of the art and the limits of hot metallic shells measurement systems suggested in literature. Our implemented system which is based on two conventional Time Of Flight (TOF) laser scanners has been described in the same chapter along, chapter two, with presentation of its respective numerical simulator. Simulation series have been done using the digitizing simulator and were aimed to determine the optimal positions of the two scanners without any industrial constraints (time, difficulty of operations). The third part of the manuscript copes with 3D primitives extraction. Two major types of approaches have been studied according to the primitive’s form (cylinders or spheres) to be extracted: supervised method and automatic method. The first approach, based on a growing region method and active contour, enables to extract complex extruded forms; while problems of ergonomics have been solved using automatic methods that have been carried out along the programme research. The proposed methods consist in automatically extracting: oval or circular cylindrical forms, using Gauss map associated with ellipse extraction techniques : spherical forms, using heuristic approaches such as RANdom SAmple Consensus RANSAC, Genetic Algorithm (GA) and Niche Genetic Algorithm (NGA). Two varieties of 3D data registration approach have been presented and discussed in chapter 4: the registration based on the artificial targets and the fine registration based on algorithm ICP. A complete system for three-dimensional characterization of hot cylindrical metallic shells during forging process has been implemented and then compared with existing systems in order to identify its performances and limits in conclusion.
36

Development of a Level-0 Geoprocessing Platform for a Multispectral Remote Sensing Payload / Utveckling av en nivå-0-geobehandlingsplattform för en multispektral fjärravkänningsnyttolast

Bernabeu Peñalba, Sergio Santiago January 2022 (has links)
This thesis presented an overview of the development of a geolocating algorithm as part of a geoprocessor for raw satellite imagery. This algorithm was devised for and limited by the specifications of a state-of-the-art multispectral telescope designed by Aistech Space, hosted onboard the Guardian spacecraft, which will observe Earth through the visible, near infrared, and thermal infrared bands of the electromagnetic spectrum. The geolocation algorithm presented here is composed of the combination of two models. The first is a physical model, which makes use of spacecraft telemetry and external satellite-tracking data to approximate the geographical center of a sensed scene. Secondly, an optical model obtains a reference Landsat image based on the timestamp and approximated location of the sensed scene and utilizes image processing techniques to pinpoint a more precise geographical location of the sensed scene within acceptable limits. This performance was achieved in 77% of the cases considered. To conclude, a roadmap of the subsequent development topics and their relevance was laid out. / Detta examensarbete presenterar en översikt för utvecklingen av en geolokaliseringsalgoritm som en del av en geoprocessor för obearbetade satellitbilder. Algoritmen anpassades för och begränsades av specifikationerna för ett toppmodernt multispektralt teleskop designat av Aistech Space. Teleskopet kommer att finnas ombord på rymdfarkosten Guardian, där den är avsedd att observera jorden i de synliga, nära infraröda och termiska infraröda delarna av det elektromagnetiska spektrumet. Geolokaliseringsalgoritmen som presenteras i detta arbete är sammansatt av en kombination av två modeller. Den första är en fysisk modell, vilken använder sig av rymdfarkostens telemetri och extern satellitspårningsdata för att approximera det geografiska centrumet av en plats. Den andra är en optisk modell, vilken använder sig av en Landsat-referensbild baserad på tidsstämpeln och den ungefärliga positionen av platsen och använder sedan bildbehandlingstekniker för att fastställa en mer exakt geografisk position av platsen inom acceptabla gränser. Denna prestation lyckades uppnås i 77% av de övervägda fallen. Avslutningsvis lades en plan ut för de efterföljande utvecklingsämnena och deras relevans.
37

Sistema de detecção em tempo real de faixas de sinalização de trânsito para veículos inteligentes utilizando processamento de imagem

Alves, Thiago Waszak January 2017 (has links)
A mobilidade é uma marca da nossa civilização. Tanto o transporte de carga quanto o de passageiros compartilham de uma enorme infra-estrutura de conexões operados com o apoio de um sofisticado sistema logístico. Simbiose otimizada de módulos mecânicos e elétricos, os veículos evoluem continuamente com a integração de avanços tecnológicos e são projetados para oferecer o melhor em conforto, segurança, velocidade e economia. As regulamentações organizam o fluxo de transporte rodoviário e as suas interações, estipulando regras a fim de evitar conflitos. Mas a atividade de condução pode tornar-se estressante em diferentes condições, deixando os condutores humanos propensos a erros de julgamento e criando condições de acidente. Os esforços para reduzir acidentes de trânsito variam desde campanhas de re-educação até novas tecnologias. Esses tópicos têm atraído cada vez mais a atenção de pesquisadores e indústrias para Sistemas de Transporte Inteligentes baseados em imagens que visam a prevenção de acidentes e o auxilio ao seu motorista na interpretação das formas de sinalização urbana. Este trabalho apresenta um estudo sobre técnicas de detecção em tempo real de faixas de sinalização de trânsito em ambientes urbanos e intermunicipais, com objetivo de realçar as faixas de sinalização da pista para o condutor do veículo ou veículo autônomo, proporcionando um controle maior da área de tráfego destinada ao veículo e prover alertas de possíveis situações de risco. A principal contribuição deste trabalho é otimizar a formar como as técnicas de processamento de imagem são utilizas para realizar a extração das faixas de sinalização, com o objetivo de reduzir o custo computacional do sistema. Para realizar essa otimização foram definidas pequenas áreas de busca de tamanho fixo e posicionamento dinâmico. Essas áreas de busca vão isolar as regiões da imagem onde as faixas de sinalização estão contidas, reduzindo em até 75% a área total onde são aplicadas as técnicas utilizadas na extração de faixas. Os resultados experimentais mostraram que o algoritmo é robusto em diversas variações de iluminação ambiente, sombras e pavimentos com cores diferentes tanto em ambientes urbanos quanto em rodovias e autoestradas. Os resultados mostram uma taxa de detecção correta média de 98; 1%, com tempo médio de operação de 13,3 ms. / Mobility is an imprint of our civilization. Both freight and passenger transport share a huge infrastructure of connecting links operated with the support of a sophisticated logistic system. As an optimized symbiosis of mechanical and electrical modules, vehicles are evolving continuously with the integration of technological advances and are engineered to offer the best in comfort, safety, speed and economy. Regulations organize the flow of road transportation machines and help on their interactions, stipulating rules to avoid conflicts. But driving can become stressing on different conditions, leaving human drivers prone to misjudgments and creating accident conditions. Efforts to reduce traffic accidents that may cause injuries and even deaths range from re-education campaigns to new technologies. These topics have increasingly attracted the attention of researchers and industries to Image-based Intelligent Transportation Systems that aim to prevent accidents and help your driver in the interpretation of urban signage forms. This work presents a study on real-time detection techniques of traffic signaling signs in urban and intermunicipal environments, aiming at the signaling lanes of the lane for the driver of the vehicle or autonomous vehicle, providing a greater control of the area of traffic destined to the vehicle and to provide alerts of possible risk situations. The main contribution of this work is to optimize how the image processing techniques are used to perform the lanes extraction, in order to reduce the computational cost of the system. To achieve this optimization, small search areas of fixed size and dynamic positioning were defined. These search areas will isolate the regions of the image where the signaling lanes are contained, reducing up to 75% the total area where the techniques used in the extraction of lanes are applied. The experimental results showed that the algorithm is robust in several variations of ambient light, shadows and pavements with different colors, in both urban environments and on highways and motorways. The results show an average detection rate of 98.1%, with average operating time of 13.3 ms.
38

Sistema de detecção em tempo real de faixas de sinalização de trânsito para veículos inteligentes utilizando processamento de imagem

Alves, Thiago Waszak January 2017 (has links)
A mobilidade é uma marca da nossa civilização. Tanto o transporte de carga quanto o de passageiros compartilham de uma enorme infra-estrutura de conexões operados com o apoio de um sofisticado sistema logístico. Simbiose otimizada de módulos mecânicos e elétricos, os veículos evoluem continuamente com a integração de avanços tecnológicos e são projetados para oferecer o melhor em conforto, segurança, velocidade e economia. As regulamentações organizam o fluxo de transporte rodoviário e as suas interações, estipulando regras a fim de evitar conflitos. Mas a atividade de condução pode tornar-se estressante em diferentes condições, deixando os condutores humanos propensos a erros de julgamento e criando condições de acidente. Os esforços para reduzir acidentes de trânsito variam desde campanhas de re-educação até novas tecnologias. Esses tópicos têm atraído cada vez mais a atenção de pesquisadores e indústrias para Sistemas de Transporte Inteligentes baseados em imagens que visam a prevenção de acidentes e o auxilio ao seu motorista na interpretação das formas de sinalização urbana. Este trabalho apresenta um estudo sobre técnicas de detecção em tempo real de faixas de sinalização de trânsito em ambientes urbanos e intermunicipais, com objetivo de realçar as faixas de sinalização da pista para o condutor do veículo ou veículo autônomo, proporcionando um controle maior da área de tráfego destinada ao veículo e prover alertas de possíveis situações de risco. A principal contribuição deste trabalho é otimizar a formar como as técnicas de processamento de imagem são utilizas para realizar a extração das faixas de sinalização, com o objetivo de reduzir o custo computacional do sistema. Para realizar essa otimização foram definidas pequenas áreas de busca de tamanho fixo e posicionamento dinâmico. Essas áreas de busca vão isolar as regiões da imagem onde as faixas de sinalização estão contidas, reduzindo em até 75% a área total onde são aplicadas as técnicas utilizadas na extração de faixas. Os resultados experimentais mostraram que o algoritmo é robusto em diversas variações de iluminação ambiente, sombras e pavimentos com cores diferentes tanto em ambientes urbanos quanto em rodovias e autoestradas. Os resultados mostram uma taxa de detecção correta média de 98; 1%, com tempo médio de operação de 13,3 ms. / Mobility is an imprint of our civilization. Both freight and passenger transport share a huge infrastructure of connecting links operated with the support of a sophisticated logistic system. As an optimized symbiosis of mechanical and electrical modules, vehicles are evolving continuously with the integration of technological advances and are engineered to offer the best in comfort, safety, speed and economy. Regulations organize the flow of road transportation machines and help on their interactions, stipulating rules to avoid conflicts. But driving can become stressing on different conditions, leaving human drivers prone to misjudgments and creating accident conditions. Efforts to reduce traffic accidents that may cause injuries and even deaths range from re-education campaigns to new technologies. These topics have increasingly attracted the attention of researchers and industries to Image-based Intelligent Transportation Systems that aim to prevent accidents and help your driver in the interpretation of urban signage forms. This work presents a study on real-time detection techniques of traffic signaling signs in urban and intermunicipal environments, aiming at the signaling lanes of the lane for the driver of the vehicle or autonomous vehicle, providing a greater control of the area of traffic destined to the vehicle and to provide alerts of possible risk situations. The main contribution of this work is to optimize how the image processing techniques are used to perform the lanes extraction, in order to reduce the computational cost of the system. To achieve this optimization, small search areas of fixed size and dynamic positioning were defined. These search areas will isolate the regions of the image where the signaling lanes are contained, reducing up to 75% the total area where the techniques used in the extraction of lanes are applied. The experimental results showed that the algorithm is robust in several variations of ambient light, shadows and pavements with different colors, in both urban environments and on highways and motorways. The results show an average detection rate of 98.1%, with average operating time of 13.3 ms.
39

Sistema de detecção em tempo real de faixas de sinalização de trânsito para veículos inteligentes utilizando processamento de imagem

Alves, Thiago Waszak January 2017 (has links)
A mobilidade é uma marca da nossa civilização. Tanto o transporte de carga quanto o de passageiros compartilham de uma enorme infra-estrutura de conexões operados com o apoio de um sofisticado sistema logístico. Simbiose otimizada de módulos mecânicos e elétricos, os veículos evoluem continuamente com a integração de avanços tecnológicos e são projetados para oferecer o melhor em conforto, segurança, velocidade e economia. As regulamentações organizam o fluxo de transporte rodoviário e as suas interações, estipulando regras a fim de evitar conflitos. Mas a atividade de condução pode tornar-se estressante em diferentes condições, deixando os condutores humanos propensos a erros de julgamento e criando condições de acidente. Os esforços para reduzir acidentes de trânsito variam desde campanhas de re-educação até novas tecnologias. Esses tópicos têm atraído cada vez mais a atenção de pesquisadores e indústrias para Sistemas de Transporte Inteligentes baseados em imagens que visam a prevenção de acidentes e o auxilio ao seu motorista na interpretação das formas de sinalização urbana. Este trabalho apresenta um estudo sobre técnicas de detecção em tempo real de faixas de sinalização de trânsito em ambientes urbanos e intermunicipais, com objetivo de realçar as faixas de sinalização da pista para o condutor do veículo ou veículo autônomo, proporcionando um controle maior da área de tráfego destinada ao veículo e prover alertas de possíveis situações de risco. A principal contribuição deste trabalho é otimizar a formar como as técnicas de processamento de imagem são utilizas para realizar a extração das faixas de sinalização, com o objetivo de reduzir o custo computacional do sistema. Para realizar essa otimização foram definidas pequenas áreas de busca de tamanho fixo e posicionamento dinâmico. Essas áreas de busca vão isolar as regiões da imagem onde as faixas de sinalização estão contidas, reduzindo em até 75% a área total onde são aplicadas as técnicas utilizadas na extração de faixas. Os resultados experimentais mostraram que o algoritmo é robusto em diversas variações de iluminação ambiente, sombras e pavimentos com cores diferentes tanto em ambientes urbanos quanto em rodovias e autoestradas. Os resultados mostram uma taxa de detecção correta média de 98; 1%, com tempo médio de operação de 13,3 ms. / Mobility is an imprint of our civilization. Both freight and passenger transport share a huge infrastructure of connecting links operated with the support of a sophisticated logistic system. As an optimized symbiosis of mechanical and electrical modules, vehicles are evolving continuously with the integration of technological advances and are engineered to offer the best in comfort, safety, speed and economy. Regulations organize the flow of road transportation machines and help on their interactions, stipulating rules to avoid conflicts. But driving can become stressing on different conditions, leaving human drivers prone to misjudgments and creating accident conditions. Efforts to reduce traffic accidents that may cause injuries and even deaths range from re-education campaigns to new technologies. These topics have increasingly attracted the attention of researchers and industries to Image-based Intelligent Transportation Systems that aim to prevent accidents and help your driver in the interpretation of urban signage forms. This work presents a study on real-time detection techniques of traffic signaling signs in urban and intermunicipal environments, aiming at the signaling lanes of the lane for the driver of the vehicle or autonomous vehicle, providing a greater control of the area of traffic destined to the vehicle and to provide alerts of possible risk situations. The main contribution of this work is to optimize how the image processing techniques are used to perform the lanes extraction, in order to reduce the computational cost of the system. To achieve this optimization, small search areas of fixed size and dynamic positioning were defined. These search areas will isolate the regions of the image where the signaling lanes are contained, reducing up to 75% the total area where the techniques used in the extraction of lanes are applied. The experimental results showed that the algorithm is robust in several variations of ambient light, shadows and pavements with different colors, in both urban environments and on highways and motorways. The results show an average detection rate of 98.1%, with average operating time of 13.3 ms.
40

Camera Based Navigation : Matching between Sensor reference and Video image

Olgemar, Markus January 2008 (has links)
an Internal Navigational System and a Global Navigational Satellite System (GNSS). In navigational warfare the GNSS can be jammed, therefore are a third navigational system is needed. The system that has been tried in this thesis is camera based navigation. Through a video camera and a sensor reference the position is determined. This thesis will process the matching between the sensor reference and the video image. Two methods have been implemented: normalized cross correlation and position determination through a homography. Normalized cross correlation creates a correlation matrix. The other method uses point correspondences between the images to determine a homography between the images. And through the homography obtain a position. The more point correspondences the better the position determination will be. The results have been quite good. The methods have got the right position when the Euler angles of the UAV have been known. Normalized cross correlation has been the best method of the tested methods.

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