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Analysis of 3D objects at multiple scales : application to shape matchingMellado, Nicolas 06 December 2012 (has links)
Depuis quelques années, l’évolution des techniques d’acquisition a entraîné une généralisation de l’utilisation d’objets 3D très dense, représentés par des nuages de points de plusieurs millions de sommets. Au vu de la complexité de ces données, il est souvent nécessaire de les analyser pour en extraire les structures les plus pertinentes, potentiellement définies à plusieurs échelles. Parmi les nombreuses méthodes traditionnellement utilisées pour analyser des signaux numériques, l’analyse dite scale-space est aujourd’hui un standard pour l’étude des courbes et des images. Cependant, son adaptation aux données 3D pose des problèmes d’instabilité et nécessite une information de connectivité, qui n’est pas directement définie dans les cas des nuages de points. Dans cette thèse, nous présentons une suite d’outils mathématiques pour l’analyse des objets 3D, sous le nom de Growing Least Squares (GLS). Nous proposons de représenter la géométrie décrite par un nuage de points via une primitive du second ordre ajustée par une minimisation aux moindres carrés, et cela à pour plusieurs échelles. Cette description est ensuite derivée analytiquement pour extraire de manière continue les structures les plus pertinentes à la fois en espace et en échelle. Nous montrons par plusieurs exemples et comparaisons que cette représentation et les outils associés définissent une solution efficace pour l’analyse des nuages de points à plusieurs échelles. Un défi intéressant est l’analyse d’objets 3D acquis dans le cadre de l’étude du patrimoine culturel. Dans cette thèse, nous nous étudions les données générées par l’acquisition des fragments des statues entourant par le passé le Phare d’Alexandrie, Septième Merveille du Monde. Plus précisément, nous nous intéressons au réassemblage d’objets fracturés en peu de fragments (une dizaine), mais avec de nombreuses parties manquantes ou fortement dégradées par l’action du temps. Nous proposons un formalisme pour la conception de systèmes d’assemblage virtuel semi-automatiques, permettant de combiner à la fois les connaissances des archéologues et la précision des algorithmes d’assemblage. Nous présentons deux systèmes basés sur cette conception, et nous montrons leur efficacité dans des cas concrets. / Over the last decades, the evolution of acquisition techniques yields the generalization of detailed 3D objects, represented as huge point sets composed of millions of vertices. The complexity of the involved data often requires to analyze them for the extraction and characterization of pertinent structures, which are potentially defined at multiple scales. Amongthe wide variety of methods proposed to analyze digital signals, the scale-space analysis istoday a standard for the study of 2D curves and images. However, its adaptation to 3D dataleads to instabilities and requires connectivity information, which is not directly availablewhen dealing with point sets.In this thesis, we present a new multi-scale analysis framework that we call the GrowingLeast Squares (GLS). It consists of a robust local geometric descriptor that can be evaluatedon point sets at multiple scales using an efficient second-order fitting procedure. We proposeto analytically differentiate this descriptor to extract continuously the pertinent structuresin scale-space. We show that this representation and the associated toolbox define an effi-cient way to analyze 3D objects represented as point sets at multiple scales. To this end, we demonstrate its relevance in various application scenarios.A challenging application is the analysis of acquired 3D objects coming from the CulturalHeritage field. In this thesis, we study a real-world dataset composed of the fragments ofthe statues that were surrounding the legendary Alexandria Lighthouse. In particular, wefocus on the problem of fractured object reassembly, consisting of few fragments (up to aboutten), but with missing parts due to erosion or deterioration. We propose a semi-automaticformalism to combine both the archaeologist’s knowledge and the accuracy of geometricmatching algorithms during the reassembly process. We use it to design two systems, andwe show their efficiency in concrete cases.
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Fire Severity and Regeneration Strategy Influence Shrub Patch Size and Structure Following DisturbanceMinor, Jesse, Falk, Donald, Barron-Gafford, Greg 22 June 2017 (has links)
Climate change is increasing the frequency and extent of high-severity disturbance, with potential to alter vegetation community composition and structure in environments sensitive to tipping points between alternative states. Shrub species display a range of characteristics that promote resistance and resilience to disturbance, and which yield differential post-disturbance outcomes. We investigated differences in shrub patch size and stem density in response to variations in fire severity, vegetation community, and post-disturbance reproductive strategies in Sky Island forested ecosystems in the southwestern United States. Patterns in shrub structure reflect the effects of fire severity as well as differences among species with alternate post-fire reproductive strategies. Increased fire severity correlates with larger patch sizes and greater stem densities; these patterns are observed across multiple fire events, indicating that disturbance legacies can persist for decades. High severity fire produces the largest shrub patches, and variance in shrub patch size increases with severity. High severity fire is likely to promote expansion of shrub species on the landscape, with implications for future community structure. Resprouting species have the greatest variability in patch structure, while seeding species show a strong response to disturbance: resprouting species dominateatlowdisturbanceseverities,andobligateseedersdominatehighseverityareas. Differential post-fire reproductive strategies are likely to generate distinct patterns of vegetation distribution following disturbance, with implications for community composition at various scales. Shrub species demonstrate flexible responses to wildfire disturbance severity that are reflected in shrub patch dynamics at small and intermediate scales.
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Une nouvelle méthode d’appariement de points d’intérêt pour la mise en correspondance d’images / A new descriptor of points of interest for matching imagesPalomares, Jean-Louis 25 October 2012 (has links)
Ce mémoire de thèse traite de la mise en correspondance d'images pour des applications de vision stéréoscopique ou de stabilisation d'images de caméras vidéo. les méthodes de mise en correspondance reposent généralement sur l'utilisation de points d'intérêts dans les images, c'est-à-dire de points qui présentent de fortes discontinuités d'intensité lumineuse. Nous présentons tout d'abord un nouveau descripteur de points d'intérêt, obtenu au moyen d'un filtre anisotropique rotatif qui délivre en chaque point d'intérêt une signature mono-dimensionnelle basée sur un gradient d'intensité. Invariant à la rotationpar construction, ce descripteur possède de trés bonnes propriétés de robustesse et de discrimination. Nous proposons ensuite une nouvelle méthode d'appariement invariante aux transformations euclidiennes et affines. Cette méthode exploite la corrélation des signatures sous l'hypothèse de faibles déformations, et définit une mesure de distance nécessaire à l'appariement de points. Les résultats obtenus sur des images difficiles laissent envisager des prolongements prometteurs de cette méthode. / This thesis adresses the issue of image matching for stereoscopic vison applications and image stabilization of video cameras. Methods of mapping are generally based on the use of interest points in the images, i.e. of points which have strong discontinuities in light intensity. We first present a new descriptor of points of interest, obtained by means of an anisotropic rotary filter which delivers at each point of interest a one-dimensional signature based on an intensity gradient. Invariant to rotation by construction, thisdescriptor has very good properties of robustness and discrimination. We then propose a new matching method invariant to Euclidean and affine transformations. This method exploits the correlation of the signatures subject to moderate warping, and defines a distance measure, necesssary for the matching of points. the results obtained on difficult images augur promising extentions to this method.
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Trestání přestupků a bodový systém v zákoně o provozu na pozemních komunikacích / Punishing administrative transgressions and the system of penalty points under the Highway Traffic ActFerancová, Zuzana January 2012 (has links)
Punishing of administrative transgressions and the system of penalty points under the Highway Traffic Act Abstract The content of the diploma thesis focuses on matter of the system of penalty points and selected issues regarding punishing of administrative transgressions. The paper is composed of five parts. Chapter One introduces Czechoslovak historical predecessors of the system of penalty points and examines the development of its current legal regulation in the Highway Traffic Act. The second part deals with fundamental principles of the system of penalty points and particularly assesses the function of prevention principle. The following chapter analyzes the actual legal regulation of the system of penalty points. The author warns against relating insufficiencies and recommends the appropriate solution. The goal of the Chapter Four is based on survey of the fact, whether the system of penalty points represents the sanction by its nature. The author critically researches the proportionality of the system of penalty points and its accordance with the Czech constitutional order. This chapter also concerns with judicial decisions of Czech courts and the European Court of Human Rights referring to the character of the system of penalty points. The last chapter evaluates the proportionality and compliance...
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Development of the Distributed Points Method with Application to Cavitating FlowBourg, David M. 19 December 2008 (has links)
A mesh-less method for solving incompressible, multi-phase flow problems has been developed and is discussed along with the presentation of benchmark results showing good agreement with theoretical and experimental results. Results of a systematic, parametric study of the single phase flow around a 2D circular cylinder at Reynolds numbers up to 1000 are presented and discussed. Simulation results show good agreement with experimental results. Extension of the method to deal with multiphase flow including liquid-to-vapor phase transition along with applications to cavitating flow are discussed. Insight gleaned from numerical experiments of the cavity closure problem are discussed along with recommendations for additional research. Several conclusions regarding the use of the method are made.
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Češi a Slováci v první sezóně druhého století NHL / Czechs and Slovaks in the first season of the second century NHLMajerová, Kamila January 2019 (has links)
Title: Czechs and Slovaks in the first season of the second century of NHL Abstract The theme od the thesis are Czechs and Slovaks in the first season of the second century of NHL. The main aim of my work is to analyze the course of the season 2017-2018. In my work I will focus on the Czech and Slovak players and their comparison with players from the other European countries and with USA and Canada ice hockey superpowers. The comparison will be focused on the number of players, Canadian points, players' productivity in the 2017 NHL Entry Draft, their average age, and the players' age versus productivity. I will also focus on the team statistics (representation of Czechs, Slovaks and Europeans in each team). Key words Ice hockey, NHL, ice hockey players, Czechs, Slovaks, Europeans, goals, points
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Light groups of isometries and polyhedrality of Banach spaces / Grupos leves de isometrias e poliedralidade de espaços de BanachAntunes, Leandro 17 June 2019 (has links)
Megrelishvili defines light groups of isomorphisms of a Banach space as the groups on which the weak and strong operator topologies coincide and proves that every bounded group of isomorphisms of Banach spaces with the point of continuity property (PCP) is light. We investigate this concept for isomorphism groups G of classical Banach spaces X without the PCP, especially isometry groups, and relate it to the existence of G-invariant LUR or strictly convex renormings of X. We give an example of a Banach space X and an infinite countable group of isomorphisms G < GL(X) which is SOT-discrete but such that X does not admit a distinguished point for G, providing a negative answer to a question of Ferenczi and Rosendal. We also prove that every combinatorial Banach space is (V)- polyhedral. In particular, the Schreier spaces of countable order provide new solutions to a problem proposed by Lindenstrauss concerning the existence of an infinite-dimensional Banach space whose unit ball is the closed convex hull of its extreme points. / Megrelishvili define grupos leves de isomorfismos de um espaço de Banach como os grupos em que as topologias fraca e forte do operador coincidem e prova que todo grupo limitado de isomorfismos de espaços de Banach com a propriedade do ponto de continuidade (PCP) é leve. Investigamos esse conceito para grupos de isomorfismos de espaços de Banach clássicos sem PCP, especialmente grupos de isometrias, e o relacionamos com a existência de renormações G-invariantes LUR ou uniformemente convexas. Damos um exemplo de um espaço de Banach X e um grupo enumerável infinito de isomorfismos G < GL(X) que é SOT-discreto mas tal que X não admite ponto distinto em relação a G, fornecendo uma resposta negativa a uma questão de Ferenczi e Rosendal. Também provamos que todos espaços de Banach combinatórios são (V)-poliedrais. Em particular, os espaços de Schreier de ordem enumerável fornecem novas soluções para um problema proposto por Lindenstrauss sobre a existência de um espaço de Banach de dimensão infinita cuja bola unitária seja igual a envoltória convexa fechada de seus pontos extremos.
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Exploring the customer journey : An exploratory study investigating the customer journeyBolinder, Marcus, Philip, Boström January 2019 (has links)
The customer journey is a re-submerged subject which has become increasingly relevant. The focus derives from the increased focus on customer experience as touch points are increasing as well as becoming more accessible. This is creating problems for companies to allocate their resources in marketing. Previous literature on customer journeys are also limited, mostly originating from research on customer experience. This motivates research within the field with the purpose of exploring the customer journey and connected phenomena. The basis of this thesis was the customer journey which derives from customer experience. Further, the theoretical framework presents theories about customer experience, consumer buying decisions, customer journey and its touch points. The theoretical framework also presents two conceptual models concerning customer journey and customer experience. Focus was here on exploring the formulation of the customer journey, its steps and components. But also, on investigating how customer experiences affects customer journeys. This thesis had a qualitative research strategy and empirical material was collected through interviews. The empirical findings and the analysis resulted in several conclusions as this was an exploratory study. Reason for use of route, use of different touch points, customer experience impact and were found. Furthermore, the customer journey itself was identified as a reason for conducting a purchase. The result of this thesis might help companies allocate their resources more efficiently between touch points. As well as understanding how to create positive customer experience and the importance of it.
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Livsberättelser om att flytta till äldreboende : vändpunkter för ensamstående äldre kvinnorEngman, Cecilia, Magnusson, Sofia January 2019 (has links)
Syftet med studien är att belysa och få ökad förståelse för hur ensamstående äldre kvinnorupplever sin flytt till äldreboende och vad god ålderdom är. Tre kvinnor har intervjuats i enkvalitativ studie med djupintervjuer som grund för den hermeneutiska tolkningen. Analysenär gjord utifrån teoretiskt livsloppsperspektiv, aktivitetsperspektiv samt genusperspektiv.Resultatet visade att upplevelsen av flytt berodde på varierande faktorer och individuellaerfarenheter. När flytten var efterlängtad upplevdes den som positiv, när flytten var mer ellermindre oundviklig var den svårare att acceptera. Vad god ålderdom innebar kan relateras tilltrygghet och tillgång till personal, ett gott utbud av aktiviteter samt goda sociala relationer.Att flytten var en vändpunkt var alla överens om. / The purpose of the study is to illustrate and gain an increased understanding of how singleelderly women experience their move to retirement homes and the resulting effects of theirquality of life. Three women have been interviewed in a qualitative study with in-depthinterviews as the basis for the hermeneutic interpretation. The analysis is made from thetheoretical perspectives of life span, activities and gender. The result showed that theexperience of moving was due to varying factors and individual experiences. When the movewas long awaited, it was perceived as positive, when the move was more or less inevitable, itwas more difficult to accept. The result also showed that quality of life was safety related toadequate staffing, a large range of attractive activities and the opportunity to be sociallyactive. That the move was a turning point was agreed upon by all.
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Bifurcação de pontos axiumbílicos e ciclos axiais de superfícies imersas em R4 / Bifurcation of axiumbilic points and axial cycles of surfaces immersed into R4Spíndola, Flausino Lucas Neves 06 May 2015 (has links)
O objetivo deste trabalho é descrever a estrutura das linhas axiais principais e médias de imersões de superfícies em R4 na vizinhança de pontos axiumbílicos. Pontos axiumbílicos são aqueles nos quais a elipse de curvatura se degenera em um círculo. Estudamos a perturbação dos ciclos axiais principais, e obtemos resultados sobre a genericidade dos ciclos axiais principais hiperbólicos e semi-hiperbólicos. / The aim of this work is to describe the structure of principal and mean axial lines of immersions of surfaces into R4, close to axiumbilic points. Axiumbilic points are those which the ellipse of curvature denegerate in a circle. We study the perturbation of principal axial cycles, and we obtain results about genericity of hyperbolic and semi-hyperbolic principal axial cycles.
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