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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.
21

Approches 2D/2D pour le SFM à partir d'un réseau de caméras asynchrones / 2D/2D approaches for SFM using an asynchronous multi-camera network

Mhiri, Rawia 14 December 2015 (has links)
Les systèmes d'aide à la conduite et les travaux concernant le véhicule autonome ont atteint une certaine maturité durant ces dernières aimées grâce à l'utilisation de technologies avancées. Une étape fondamentale pour ces systèmes porte sur l'estimation du mouvement et de la structure de l'environnement (Structure From Motion) pour accomplir plusieurs tâches, notamment la détection d'obstacles et de marquage routier, la localisation et la cartographie. Pour estimer leurs mouvements, de tels systèmes utilisent des capteurs relativement chers. Pour être commercialisés à grande échelle, il est alors nécessaire de développer des applications avec des dispositifs bas coûts. Dans cette optique, les systèmes de vision se révèlent une bonne alternative. Une nouvelle méthode basée sur des approches 2D/2D à partir d'un réseau de caméras asynchrones est présentée afin d'obtenir le déplacement et la structure 3D à l'échelle absolue en prenant soin d'estimer les facteurs d'échelle. La méthode proposée, appelée méthode des triangles, se base sur l'utilisation de trois images formant un triangle : deux images provenant de la même caméra et une image provenant d'une caméra voisine. L'algorithme admet trois hypothèses: les caméras partagent des champs de vue communs (deux à deux), la trajectoire entre deux images consécutives provenant d'une même caméra est approximée par un segment linéaire et les caméras sont calibrées. La connaissance de la calibration extrinsèque entre deux caméras combinée avec l'hypothèse de mouvement rectiligne du système, permet d'estimer les facteurs d'échelle absolue. La méthode proposée est précise et robuste pour les trajectoires rectilignes et présente des résultats satisfaisants pour les virages. Pour affiner l'estimation initiale, certaines erreurs dues aux imprécisions dans l'estimation des facteurs d'échelle sont améliorées par une méthode d'optimisation : un ajustement de faisceaux local appliqué uniquement sur les facteurs d'échelle absolue et sur les points 3D. L'approche présentée est validée sur des séquences de scènes routières réelles et évaluée par rapport à la vérité terrain obtenue par un GPS différentiel. Une application fondamentale dans les domaines d'aide à la conduite et de la conduite automatisée est la détection de la route et d'obstacles. Pour un système asynchrone, une première approche pour traiter cette application est présentée en se basant sur des cartes de disparité éparses. / Driver assistance systems and autonomous vehicles have reached a certain maturity in recent years through the use of advanced technologies. A fundamental step for these systems is the motion and the structure estimation (Structure From Motion) that accomplish several tasks, including the detection of obstacles and road marking, localisation and mapping. To estimate their movements, such systems use relatively expensive sensors. In order to market such systems on a large scale, it is necessary to develop applications with low cost devices. In this context, vision systems is a good alternative. A new method based on 2D/2D approaches from an asynchronous multi-camera network is presented to obtain the motion and the 3D structure at the absolute scale, focusing on estimating the scale factors. The proposed method, called Triangle Method, is based on the use of three images forming a. triangle shape: two images from the same camera and an image from a neighboring camera. The algorithrn has three assumptions: the cameras share common fields of view (two by two), the path between two consecutive images from a single camera is approximated by a line segment, and the cameras are calibrated. The extrinsic calibration between two cameras combined with the assumption of rectilinear motion of the system allows to estimate the absolute scale factors. The proposed method is accurate and robust for straight trajectories and present satisfactory results for curve trajectories. To refine the initial estimation, some en-ors due to the inaccuracies of the scale estimation are improved by an optimization method: a local bundle adjustment applied only on the absolute scale factors and the 3D points. The presented approach is validated on sequences of real road scenes, and evaluated with respect to the ground truth obtained through a differential GPS. Finally, another fundamental application in the fields of driver assistance and automated driving is road and obstacles detection. A method is presented for an asynchronous system based on sparse disparity maps
22

IVORA (Image and Computer Vision for Augmented Reality) : Color invariance and correspondences for the definition of a camera/video-projector system / IVORA (Image et Vision par Ordinateur pour la Réalité Augmentée) : Invariance colorimétrique et correspondances pour la définition d'un système projecteur/caméra

Setkov, Aleksandr 27 November 2015 (has links)
La Réalité Augmentée Spatiale (SAR) vise à superposer spatialement l'information virtuelle sur des objets physiques. Au cours des dernières décennies ce domaine a connu une grande expansion et est utilisé dans divers domaines, tels que la médecine, le prototypage, le divertissement etc. Cependant, pour obtenir des projections de bonne qualité, on doit résoudre plusieurs problèmes, dont les plus importants sont la gamme de couleurs réduite du projecteur, la lumière ambiante, la couleur du fond, et la configuration arbitraire de la surface de projection dans la scène. Ces facteurs entraînent des distorsions dans les images qui requièrent des processus de compensation complémentaires.Les projections intelligentes (smart projections) sont au cœur des applications de SAR. Composées d'un dispositif de projection et d'un dispositif d'acquisition, elles contrôlent l'aspect de la projection et effectuent des corrections à la volée pour compenser les distorsions. Bien que les méthodes actives de Lumière Structurée aient été utilisées classiquement pour résoudre ces problèmes de compensation géométrique, cette thèse propose une nouvelle approche non intrusive pour la compensation géométrique de plusieurs surfaces planes et pour la reconnaissance des objets en SAR s'appuyant uniquement sur la capture du contenu projeté.Premièrement, cette thèse étude l'usage de l'invariance couleur pour améliorer la qualité de la mise en correspondance entre primitives dans une configuration d'acquisition des images vidéoprojetées. Nous comparons la performance de la plupart des méthodes de l'état de l'art avec celle du descripteur proposé basé sur l'égalisation d'histogramme. Deuxièmement, pour mieux traiter les conditions standard des systèmes projecteur-caméra, deux ensembles de données de captures de projections réelles, ont été spécialement préparés à des fins expérimentales. La performance de tous les algorithmes considérés est analysée de façon approfondie et des propositions de recommandations sont faites sur le choix des algorithmes les mieux adaptés en fonction des conditions expérimentales (paramètres image, disposition spatiale, couleur du fond...). Troisièmement, nous considérons le problème d'ajustement multi-surface pour compenser des distorsions d'homographie dans les images acquises. Une combinaison de mise en correspondance entre les primitives et de Flux Optique est proposée afin d'obtenir une compensation géométrique plus rapide. Quatrièmement, une nouvelle application en reconnaissance d'objet à partir de captures d'images vidéo-projetées est mise en œuvre. Finalement, une implémentation GPU temps réel des algorithmes considérés ouvre des pistes pour la compensation géométrique non intrusive en SAR basée sur la mise en correspondances entre primitives. / Spatial Augmented Reality (SAR) aims at spatially superposing virtual information on real-world objects. Over the last decades, it has gained a lot of success and been used in manifold applications in various domains, such as medicine, prototyping, entertainment etc. However, to obtain projections of a good quality one has to deal with multiple problems, among them the most important are the limited projector output gamut, ambient illumination, color background, and arbitrary geometric surface configurations of the projection scene. These factors result in image distortions which require additional compensation steps.Smart-projections are at the core of PAR applications. Equipped with a projection and acquisitions devices, they control the projection appearance and introduce corrections on the fly to compensate distortions. Although active structured-light techniques have been so far the de-facto method to address such problems, this PhD thesis addresses a relatively new unintrusive content-based approach for geometric compensation of multiple planar surfaces and for object recognition in SAR.Firstly, this thesis investigates the use of color-invariance for feature matching quality enhancement in projection-acquisition scenarios. The performance of most state-of-the art methods are studied along with the proposed local histogram equalization-based descriptor. Secondly, to better address the typical conditions encountered when using a projector-camera system, two datasets of real-world projections were specially prepared for experimental purposes. Through a series of evaluation frameworks, the performance of all considered algorithms is thoroughly analyzed, providing several inferences on that which algorithms are more appropriate in each condition. Thirdly, this PhD work addresses the problem of multiple-surface fitting used to compensate different homography distortions in acquired images. A combination of feature matching and Optical Flow tracking is proposed in order to achieve a more low-weight geometric compensation. Fourthly, an example of new application to object recognition from acquired projections is showed. Finally, a real-time implementation of considered methods on GPU shows prospects for the unintrusive feature matching-based geometric compensation in SAR applications.
23

Design and implementation of an affordable reversing camera system with object detection and OBD-2 integration for commercial vehicles / Design och implementering av ett prisvärt backkamerasystem med objektdetektering och OBD-2-integration för kommersiella fordon

Ebrahimi, Alireza, Akbari, Esmatullah January 2023 (has links)
This thesis is about designing and implementing an affordable reversing camera sys-tem with object detection and OBD-2 integration for commercial vehicles. The aim is to improve the safety and efficiency of these vehicles by giving drivers a clear view of their surroundings behind the vehicle and alerting them to the presence of nearby obstacles. Ultrasonic sensors are used for object detection and give the driver control over the environment behind the vehicle and warn of present obstacles. The system is also integrated with the vehicle's on-board diagnostics system (OBD-2), which provides important information on speed and engine performance, among other things. This project contributes to making safety systems more accessible to com-mercial vehicles and reduces the risk of accidents and collisions. / Detta examensarbete handlar om att utforma och implementera ett prisvärt backkamerasystem objektdetektering och integration med On-Board Diagnostics 2 för kommersiella fordon. Syftet är att förbättra säkerheten och effektiviteten för dessa fordon genom att ge förarna en tydlig vy av deras omgivningar bakom fordonet och varna dem för närvaron av hinder i närheten. Ultraljudssensorer används för objekt-detektering och ger föraren en kontroll över omgivningen bakom fordonet samt var-nar för närvarande hinder. Systemet är också integrerat med fordonets omborddia-gnostiksystem (OBD-2), som ger viktig information om bland annat hastighet och motorprestanda. Detta projekt bidrar till att göra säkerhetssystem mer tillgängliga för kommersiella fordon och minskar risken för olyckor och kollisioner.
24

Utvärdering av noggrannheten av kastparablar på en iPad / Accuracy evaluation of trajectories on an iPad

Waninger, Mikael, Rothman, Sofia January 2022 (has links)
Prestationsmätning och analys används inom sporter för att förbättra en spelares resultat relaterade till sin respektive sport. För analys finns labb och/eller dyr utrustning vilket gör den svårtillgänglig för icke-professionella utövare. Att minska kostnaden för mätverktyg bidrar till mer jämlika förutsättningar för spelare oavsett inkomst eller ålder. Den här studien syftar till att undersöka om en smartphone eller surfplatta kan användas för mätning och sportanalys. För att utforska detta utvecklades en applikation med fokus på projektilsporter som fotboll, tennis och golf. Applikationen testar visualisering av ett objekts parabel, mätning av dess hastighet och visualisering av dess träff i ett vertikalt plan. Applikationen utvecklades för iOS och testades på en iPad 12 pro. Tester för att validera applikationens noggrannhet utfördes med en fotboll, en tennisboll och en golfboll. Testresultaten för visualisering av parabel gav resultat för fotboll och tennisboll men kunde inte hantera golfbollens mindre storlek. Hastighet kunde mätas för alla tre bollar med en genomsnittlig procentuell avvikelse på 76% för fotboll, 21% för tennisboll och 43% för golfboll. Testresultaten för visualisering av ett objekts träff i ett målplan visade resultat för fotboll och tennisboll, men inte för en golfboll. Den genomsnittliga procentuella avvikelsen var 89% för fotboll respektive 23% för tennisboll. / Measuring and analyzing player performance within sports helps to improve a players results in regards to their respective sport. Specialized labs and or expensive equipment are used for analysis but are difficult to access for the average player. Decreasing the cost of measurement tools would help equalize the playing field for players regardless of age or economic background. This study evaluates if a smartphone or tablet can be used to perform the same task. To achieve this an application was developed with a focus on projectile sports such as soccer, tennis, or golf. The application will visualize a parabola, measure speed, and visualize the point where an object hits a vertical plane. The application was developed for iOS and was tested on an iPad 12 pro. The tests were performed with a soccer ball, tennis ball and golf ball. Tests for visualizing a parabola produced results for the soccer ball and the tennis ball but could not handle the golf balls smaller size. Speed was measured for all three balls with an average percentual offset of 76% for the soccer ball, 21% for the tennis ball and 43% for the golf ball. Hit on a vertical plan produced results for the soccer ball and tennis ball with an average percentual offset of 89% for the soccer ball and 23% for the tennis ball.
25

Ein generisches Abbildungsmodell für Stereokamerasysteme / Modellierung, Kalibrierung, Evaluierung und Anwendung

Luber, Andreas 19 January 2015 (has links)
In den letzten Jahren kommen immer mehr nicht perspektivische Kamerasysteme beim maschinellen Sehen zur Anwendung, die vor allem ein deutlich erweitertes Blickfeld bieten. Das klassische perspektivische Abbildungsmodell lässt sich hier häufig nicht mehr erfolgreich anwenden. In dieser Arbeit wird ein generisches Abbildungsmodell vorgestellt, welches übliche Kamerasysteme akkurat modellieren kann. Solche Kamerasysteme schließen insbesondere klassische perspektivische Systeme, aber auch Fischaugen- und Spiegellinsen-Kamerasysteme ein. Die Nutzung eines einheitlichen Abbildungsmodells ermöglicht schließlich eine einfache Verwendung und Kalibrierung von heterogenen Stereokamerasystemen, also einer Kombination von unterschiedlichen Kameratypen, die vorteilhafte Eigenschaften gegenüber klassischen Stereosystemen bieten. Nicht zuletzt trägt die in dieser Arbeit vorgestellte einheitliche Modellierung und Kalibrierung von Mono- und Stereokamerasystemen dazu bei, Fehler durch falschen Umgang oder falsche Wahl von Methoden der Modellierung oder Kalibrierung zu vermeiden und den Kamerakalibrierprozess insgesamt zu vereinfachen. In dieser Arbeit wurden verschiedene Ansätze der Modellierung untersucht und evaluiert. Es wurde eine generische Modellierung vorgeschlagen, die die untersuchten spezifischen Abbildungsmodelle vollständig ersetzen kann. Für die Kalibrierung nicht linearer Abbildungsmodelle wurde eine einheitliche Methode zur Startwertbestimmung vorgeschlagen und evaluiert. Die Genauigkeit der Kalibrierung mittels einheitlicher Methoden wurde anhand diverser realer Kamerasysteme untersucht und bewertet. Es konnte gezeigt werden, dass die dabei auftretenden Fehler deutlich im Subpixelbereich liegen. Durch Erweiterung des klassischen Konzepts der Epipolargeometrie um die generische Abbildungsmodellierung konnten schließlich heterogene Stereokamerasysteme kalibriert und genaue Stereomodelle abgeleitet werden. / The application of perspective camera systems in photogrammetry and computer vision is state of the art. In recent years non-perspective and especially omnidirectional camera systems have increasingly been used in close-range photogrammetry tasks. In general, the perspective camera model, i.e. pinhole model, cannot be applied when using non-perspective camera systems. However, several camera models for different omnidirectional camera systems are proposed in literature. Using different types of cameras in a heterogeneous camera system may lead to an advantageous combination. The advantages of different camera systems, e.g. field of view and resolution, result in a new enhanced camera system. If these different kinds of cameras can be modeled, using a unified camera model, the total calibration process can be simplified. Sometimes it is not possible to give the specific camera model in advance. In these cases a generic approach is helpful too. Furthermore, a simple stereo reconstruction becomes possible when using a fisheye and a perspective camera for example. In this work camera models for perspective, wide-angle and omnidirectional camera systems were evaluated. A generic camera model were introduced that fully substitutes specific camera models. The crucial initialization of the model''s parameters is conducted using a new generic method that is independent of the particular camera system. The accuracy of this generic camera calibration approach is validated by the calibration of a dozen of real camera systems up to subpixel accuracy. Finally, it has been shown that a unified method of modeling, parameter approximation and calibration of interior and exterior orientation can be applied to a generic stereo system to derive precise 3D object data.
26

Design and Calibration of a Network of RGB-D Sensors for Robotic Applications over Large Workspaces

Rizwan, Macknojia 21 March 2013 (has links)
This thesis presents an approach for configuring and calibrating a network of RGB-D sensors used to guide a robotic arm to interact with objects that get rapidly modeled in 3D. The system is based on Microsoft Kinect sensors for 3D data acquisition. The work presented here also details an analysis and experimental study of the Kinect’s depth sensor capabilities and performance. The study comprises examination of the resolution, quantization error, and random distribution of depth data. In addition, the effects of color and reflectance characteristics of an object are also analyzed. The study examines two versions of Kinect sensors, one dedicated to operate with the Xbox 360 video game console and the more recent Microsoft Kinect for Windows version. The study of the Kinect sensor is extended to the design of a rapid acquisition system dedicated to large workspaces by the linkage of multiple Kinect units to collect 3D data over a large object, such as an automotive vehicle. A customized calibration method for this large workspace is proposed which takes advantage of the rapid 3D measurement technology embedded in the Kinect sensor and provides registration accuracy between local sections of point clouds that is within the range of the depth measurements accuracy permitted by the Kinect technology. The method is developed to calibrate all Kinect units with respect to a reference Kinect. The internal calibration of the sensor in between the color and depth measurements is also performed to optimize the alignment between the modalities. The calibration of the 3D vision system is also extended to formally estimate its configuration with respect to the base of a manipulator robot, therefore allowing for seamless integration between the proposed vision platform and the kinematic control of the robot. The resulting vision-robotic system defines the comprehensive calibration of reference Kinect with the robot. The latter can then be used to interact under visual guidance with large objects, such as vehicles, that are positioned within a significantly enlarged field of view created by the network of RGB-D sensors. The proposed design and calibration method is validated in a real world scenario where five Kinect sensors operate collaboratively to rapidly and accurately reconstruct a 180 degrees coverage of the surface shape of various types of vehicles from a set of individual acquisitions performed in a semi-controlled environment, that is an underground parking garage. The vehicle geometrical properties generated from the acquired 3D data are compared with the original dimensions of the vehicle.
27

Design and Calibration of a Network of RGB-D Sensors for Robotic Applications over Large Workspaces

Macknojia, Rizwan 21 March 2013 (has links)
This thesis presents an approach for configuring and calibrating a network of RGB-D sensors used to guide a robotic arm to interact with objects that get rapidly modeled in 3D. The system is based on Microsoft Kinect sensors for 3D data acquisition. The work presented here also details an analysis and experimental study of the Kinect’s depth sensor capabilities and performance. The study comprises examination of the resolution, quantization error, and random distribution of depth data. In addition, the effects of color and reflectance characteristics of an object are also analyzed. The study examines two versions of Kinect sensors, one dedicated to operate with the Xbox 360 video game console and the more recent Microsoft Kinect for Windows version. The study of the Kinect sensor is extended to the design of a rapid acquisition system dedicated to large workspaces by the linkage of multiple Kinect units to collect 3D data over a large object, such as an automotive vehicle. A customized calibration method for this large workspace is proposed which takes advantage of the rapid 3D measurement technology embedded in the Kinect sensor and provides registration accuracy between local sections of point clouds that is within the range of the depth measurements accuracy permitted by the Kinect technology. The method is developed to calibrate all Kinect units with respect to a reference Kinect. The internal calibration of the sensor in between the color and depth measurements is also performed to optimize the alignment between the modalities. The calibration of the 3D vision system is also extended to formally estimate its configuration with respect to the base of a manipulator robot, therefore allowing for seamless integration between the proposed vision platform and the kinematic control of the robot. The resulting vision-robotic system defines the comprehensive calibration of reference Kinect with the robot. The latter can then be used to interact under visual guidance with large objects, such as vehicles, that are positioned within a significantly enlarged field of view created by the network of RGB-D sensors. The proposed design and calibration method is validated in a real world scenario where five Kinect sensors operate collaboratively to rapidly and accurately reconstruct a 180 degrees coverage of the surface shape of various types of vehicles from a set of individual acquisitions performed in a semi-controlled environment, that is an underground parking garage. The vehicle geometrical properties generated from the acquired 3D data are compared with the original dimensions of the vehicle.
28

Design and Calibration of a Network of RGB-D Sensors for Robotic Applications over Large Workspaces

Macknojia, Rizwan January 2013 (has links)
This thesis presents an approach for configuring and calibrating a network of RGB-D sensors used to guide a robotic arm to interact with objects that get rapidly modeled in 3D. The system is based on Microsoft Kinect sensors for 3D data acquisition. The work presented here also details an analysis and experimental study of the Kinect’s depth sensor capabilities and performance. The study comprises examination of the resolution, quantization error, and random distribution of depth data. In addition, the effects of color and reflectance characteristics of an object are also analyzed. The study examines two versions of Kinect sensors, one dedicated to operate with the Xbox 360 video game console and the more recent Microsoft Kinect for Windows version. The study of the Kinect sensor is extended to the design of a rapid acquisition system dedicated to large workspaces by the linkage of multiple Kinect units to collect 3D data over a large object, such as an automotive vehicle. A customized calibration method for this large workspace is proposed which takes advantage of the rapid 3D measurement technology embedded in the Kinect sensor and provides registration accuracy between local sections of point clouds that is within the range of the depth measurements accuracy permitted by the Kinect technology. The method is developed to calibrate all Kinect units with respect to a reference Kinect. The internal calibration of the sensor in between the color and depth measurements is also performed to optimize the alignment between the modalities. The calibration of the 3D vision system is also extended to formally estimate its configuration with respect to the base of a manipulator robot, therefore allowing for seamless integration between the proposed vision platform and the kinematic control of the robot. The resulting vision-robotic system defines the comprehensive calibration of reference Kinect with the robot. The latter can then be used to interact under visual guidance with large objects, such as vehicles, that are positioned within a significantly enlarged field of view created by the network of RGB-D sensors. The proposed design and calibration method is validated in a real world scenario where five Kinect sensors operate collaboratively to rapidly and accurately reconstruct a 180 degrees coverage of the surface shape of various types of vehicles from a set of individual acquisitions performed in a semi-controlled environment, that is an underground parking garage. The vehicle geometrical properties generated from the acquired 3D data are compared with the original dimensions of the vehicle.
29

Měření ovality extrudovaného vlákna pomocí tří kamer / Ovality measurement of extruded fiber using three cameras

Loučka, Pavel January 2019 (has links)
One of the important parameters observed during extruded fibre fabrication is its diameter. The diameter can be measured with a single scanning camera assuming that the fibre section has a circular shape. As proved in practice, another important parameter is ovality, that is the rate of fibre flattening. This paper assumes that the fibre section shape is elliptical. In such a case, at least three different views on examined fibre are needed. Mathematical part of this paper is concerned with analytical description of fibre ovality measurement using two different approaches based on the knowledge of linear algebra, projective geometry and conic sections theory. Main goal of this paper is thus to use both mathematical theory and image analysis methods for ovality and diameter determination. Precise calcluation of such quantities is, however, conditioned on precise camera system calibration, which is described in the paper as well. Additionally, the work contains a brief mention of technical realization of ovality measurement and its possible difficulties.
30

Staniční testování Mobilního automatizovaného astronomického systému / Station testing of Mobile automated astronomical system

Sasyn, Jan January 2013 (has links)
Subject of this master´s thesis is a station testing of Mobile automated astronomical system No. 1 (MAAS – 1). This system is used for measurement of astronomical coordinates by measurments of the stars. This thesis is focused on impact of some systematic effects, especially effects of inaccurate input geographic coordinates to resulting coordinates.

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