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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.
141

Emprego de simulação computacional para avaliação de objetos simuladores impressos 3D para aplicação em dosimetria clínica / Use of computational simulation for evaluation of 3D printed phantoms for application in clinical dosimetry

Caio César Santos Valeriano 29 May 2017 (has links)
O propósito de um objeto simulador é representar a alteração do campo de radiação provocada pela absorção e espalhamento em um dado tecido ou órgão de interesse. Suas características geométricas e de composição devem estar próximos o máximo possível aos valores associados ao seu análogo natural. Estruturas anatômicas podem ser transformadas em objetos virtuais 3D por técnicas de imageamento médico (p. ex. Tomografia Computadorizada) e impressas por prototipagem rápida utilizando materiais como, por exemplo, o ácido poliláctico. Sua produção para pacientes específicos requer o preenchimento de requisitos como a acurácia geométrica com a anatomia do individuo e a equivalência ao tecido, de modo que se possa realizar medidas utilizáveis, e ser insensível aos efeitos da radiação. O objetivo desse trabalho foi avaliar o comportamento de materiais impressos 3D quando expostos a feixes de fótons diversos, com ênfase para a qualidade de radiotherapia (6 MV), visando a sua aplicação na dosimetria clínica. Para isso foram usados 30 dosímetros termoluminescentes de LiF:Mg,Ti. Foi analisada também a equivalência entre o PMMA e o PLA impresso para a resposta termoluminescente de 30 dosímetros de CaSO4:Dy. As irradiações com feixes de fótons com qualidade de radioterapia foram simuladas com o uso do sistema de planejamento Eclipse™, com o Anisotropic Analytical Algorithm e o Acuros&reg XB Advanced Dose Calculation algorithm. Além do uso do Eclipse™ e dos testes dosimétricos, foram realizadas simulações computacionais utilizando o código MCNP5. As simulações com o código MCNP5 foram realizadas para calcular o coeficiente de atenuação de placas impressas expostas a diversas qualidades de raios X de radiodiagnóstico e para desenvolver um modelo computacional de placas impressas 3D. / The purpose of a phantom is to represent the change in the radiation field caused by absorption and scattering in a given tissue or organ of interest. Its geometrical characteristics and composition should be as close as possible to the values associated with its natural analogue. Anatomical structures can be transformed into 3D virtual objects by medical imaging techniques (e.g. Computed Tomography) and printed by rapid prototyping using materials, for example, polylactic acid. Its production for specific pacients requires fulfilling requirements such as geometric accuracy with the individual\'s anatomy and tissue equivalence, so that usable measurements can be made, and be insensitive to the radiation effects. The objective of this work was to evaluate the behavior of 3D printed materials when exposed to different photon beams, with emphasis on the quality of radiotherapy (6 MV), aiming its application in clinical dosimetry. For this, 30 thermoluminescent dosimeters of LiF:Mg,Ti were used. The equivalence between the PMMA and the printed PLA for the thermoluminescent response of 30 dosimeters of CaSO4: Dy was also analyzed. The irradiations with radiotherapy photon beams were simulated using the Eclipse™ treatment planning system,with the Anisotropic Analytical Algorithm and the Acuros&reg XB Advanced Dose Calculation algorithm. In addition to the use of Eclipse™ and dosimetric tests, computational simulations were realized using the MCNP5 code. Simulations with the MCNP5 code were performed to calculate the attenuation coefficient of printed plates exposed to different radiodiagnosis X-rays qualities and to develop a computational model of 3D printed plates.
142

Contributions to accurate and efficient cost aggregation for stereo matching

Chen, Dongming 12 March 2015 (has links)
Les applications basées sur 3D tels que les films 3D, l’impression 3D, la cartographie 3D, la reconnaissance 3D, sont de plus en plus présentes dans notre vie quotidienne; elles exigent une reconstruction 3D qui apparaît alors comme une technique clé. Dans cette thèse, nous nous intéressons à l’appariement stéréo qui est au coeur de l’acquisition 3D. Malgré les nombreuses publications traitant de l’appariement stéréo, il demeure un défi en raison des contraintes de précision et de temps de calcul: la conduite autonome requiert le temps réel; la modélisation d’objets 3D exige une précision et une résolution élevées. La méthode de pondération adaptative des pixels de support (adaptative-supportweight), basée sur le bien connu filtre bilatéral, est une méthode de l’état de l’art, de catégorie locale, qui en dépit de ses potentiels atouts peine à lever l’ambiguïté induite par des pixels voisins, de disparités différentes mais avec des couleurs similaires. Notre première contribution, à base de filtre trilatéral, est une solution pertinente qui tout en conservant les avantages du filtre bilatéral permet de lever l’ambiguïté mentionnée. Evaluée sur le corpus de référence, communément acceptée, Middlebury, elle se positionne comme étant la plus précise au moment où nous écrivons ces lignes. Malgré ces performances, la complexité de notre première contribution est élevée. Elle dépend en effet de la taille de la fenêtre support. Nous avons proposé alors une implémentation récursive du filtre trilatérale, inspirée par les filtres récursifs. Ici, les coûts bruts en chaque pixel sont agrégés à travers une grille organisée en graphe. Quatre passages à une dimension permettent d’atteindre une complexité en O(N), indépendante cette fois de la taille de la fenêtre support. C’est-à-dire des centaines de fois plus rapide que la méthode originale. Pour le calcul des pondérations des pixels du support, notre méthode basée sur le filtre trilatéral introduit un nouveau terme, qui est une fonction d’amplitude du gradient. Celui-ci est remarquable aux bords des objets, mais aussi en cas de changement de couleurs et de texture au sein des objets. Or, le premier cas est déterminant dans l’estimation de la profondeur. La dernière contribution de cette thèse vise alors à distinguer les contours des objets de ceux issus du changement de couleur au sein de l’objet. Les évaluations, sur Middlebury, prouvent l’efficacité de la méthode proposée. Elle est en effet plus précise que la méthode basée sur le filtre trilatéral d’origine, mais aussi d’autres méthodes locales. / 3D-related applications are becoming more and more popular in our daily life, such as 3D movies, 3D printing, 3D maps, 3D object recognition, etc. Many applications require realistic 3D models and thus 3D reconstruction is a key technique behind them. In this thesis, we focus on a basic problem of 3D reconstruction, i.e. stereo matching, which searches for correspondences in a stereo pair or more images of a 3D scene. Although various stereo matching methods have been published in the past decades, it is still a challenging task since the high requirement of accuracy and efficiency in practical applications. For example, autonomous driving demands realtime stereo matching technique; while 3D object modeling demands high quality solution. This thesis is dedicated to develop efficient and accurate stereo matching method. The well-known bilateral filter based adaptive support weight method represents the state-of-the-art local method, but it hardly sorts the ambiguity induced by nearby pixels at different disparities but with similar colors. Therefore, we proposed a novel trilateral filter based method that remedies such ambiguities by introducing a boundary strength term. As evaluated on the commonly accepted Middlebury benchmark, the proposed method is proved to be the most accurate local stereo matching method at the time of submission (April 2013). The computational complexity of the trilateral filter based method is high and depends on the support window size. In order to enhance its computational efficiency, we proposed a recursive trilateral filter method, inspired by recursive filter. The raw costs are aggregated on a grid graph by four one-dimensional aggregations and its computational complexity proves to be O(N), which is independent of the support window size. The practical runtime of the proposed recursive trilateral filter based method processing 375 _ 450 resolution image is roughly 260ms on a PC with a 3:4 GHz Inter Core i7 CPU, which is hundreds times faster than the original trilateral filter based method. The trilateral filter based method introduced a boundary strength term, which is computed from color edges, to handle the ambiguity induced by nearby pixels at different disparities but with similar colors. The color edges consist of two types of edges, i.e. depth edges and texture edges. Actually, only depth edges are useful for the boundary strength term. Therefore, we presented a depth edge detection method, aiming to pick out depth edges and proposed a depth edge trilateral filter based method. Evaluation on Middlebury benchmark proves the effectiveness of the proposed depth edge trilateral filter method, which is more accurate than the original trilateral filter method and other local stereo matching methods.
143

[en] ENVIRONMENT COMPUTATIONAL FOR INTEGRATION OF THE SIMULATION AND OF THE VISUALISATION FOR THE DYNAMICS OF VEHICLES / [pt] AMBIENTE COMPUTACIONAL PARA INTEGRAÇÃO DA SIMULAÇÃO E DA VISUALIZAÇÃO DA DINÂMICA DE VEÍCULOS

ERNANDES PEREIRA DE OLIVEIRA 08 August 2003 (has links)
[pt] Este trabalho tem como objetivo apresentar um ambiente computacional integrado para a simulação e visualização tridimensional da dinâmica de veículos, o SVDV. O ambiente está dividido em três módulos: interface gráfica, simulação e visualização gráfica. O módulo de interface, desenvolvido em Visual Basic, gerencia os bancos de dados e serve como ligação entre os módulos de simulação e visualização gráfica. O módulo de simulação permite a inclusão de diferentes modelos de dinâmica de veículos, estando disponíveis atualmente modelos em Matlab/Simulink, Visual C++ e MS Excel. O módulo de visualização gráfica faz uso da poderosa linguagem de programação Maxscript, que emprega scripts do 3D Studio Max (3DS Max). Com esta linguagem é possível incluir inúmeros efeitos de iluminação, texturização e modelagem, disponíveis no 3DS Max, garantindo um elevado grau de realismo na visualização da simulação. / [en] This work presents na integrated computational system for the simulation and visualization of vehicular dynamics, SVDV. The system is divided in three modules: graphics interface, simulation and graphics visualization. The interface module, developed in Visual Basic, manages the databases and behaves as a link between the simulation and visualization modules. The simulation module allows the inclusion of different vehicular dynamics models. At the present stage there are models developed in Matlab/Simulink, Visual C++ and MS Excel. The graphics visualization module makes use of the powerful Maxscript programming language, a script language from 3D Studio Max (3DS Max). Hence, it is possible to incorporate a variety of illumination and texture effects and also modeling techniques from 3DS Max, thus guaranteeing a realistic visualization.
144

Využití 3D skenování pro přípravu obrábění odlitků součástí parních turbín / Using 3D Scanning for the Preparation of Steam Turbines Cast Parts for Machining

Michalisko, Jan January 2012 (has links)
The technical paper deals with the application of 3D scanning for the preparation of cast machining which is a part of steam turbines manufactured by the Industrial Turbo machinery branch office of the Siemens Ltd. in Brno. There is a theoretic explanation of general terms which relate to the 3D digitization process in the first part. Further in the theoretic part, the used digitization systems TRITOP and ATOS are described in detail. In practical part, the analysis of the current process has been carried out and the alternate process of the cast preparation for a subsequent machining has been suggested. By means of above mentioned systems, the cast has been converted in a digital form and compared with the source CAD module. The comparison results in material allowance check and the suitable setting for a following machining process. In conclusion, the technical economic evaluation of both processes has been carried out.
145

Using Multiview Annotation to Annotate Multiple Images Simultaneously

Price, Timothy C. 01 June 2017 (has links)
In order for a system to learn a model for object recognition, it must have a lot of positive images to learn from. Because of this, datasets of similar objects are built to train the model. These object datasets used for learning models are best when large, diverse and have annotations. But the process of obtaining the images and creating the annotations often times take a long time, and are costly. We use a method that obtains many images of the same objects in different angles very quickly and then reconstructs those images into a 3D model. We then use the 3D reconstruction of these images of an object to connect information about the different images of the same object together. We use that information to annotate all of the images taken very quickly and cheaply. These annotated images are then used to train the model.
146

Analyse statistique de la diversité en anthropometrie tridimensionnelle / Statistical analysis of diversity in three-dimensional anthropometry

Kollia, Aikaterini 13 January 2016 (has links)
L’anthropométrie est le domaine scientifique qui étudie les dimensions du corps humain. La complexité de la morphologie du corps nécessite une analyse 3D, aujourd’hui permise par les progrès des scanners 3D. L’objectif de cette étude est de comparer les populations et utiliser les résultats pour mieux adapter les produits sportifs à la morphologie des utilisateurs. Des campagnes de mensuration 3D ont été réalisées et des algorithmes de traitement automatique ont été créés pour analyser les nuages de points des sujets scannés. Basés sur les méthodes d’images et de géométrie, ces algorithmes repèrent des points anatomiques, calculent des mesures 1D, alignent les sujets scannés et créent des modèles anthropométriques 3D représentatifs des populations. Pour analyser les caractéristiques anthropométriques, des statistiques de premier ordre et factorielles ont été adaptées pour être utilisées dans l’espace 3D. Les méthodes ont été appliquées à trois parties : le pied, la tête et la poitrine. Les différences morphologiques entre les populations, mais également au sein d’une population donnée, ont été révélées. Par exemple, la différence à chaque point de la tête entre des têtes a été calculée. Les statistiques en trois dimensions ont aussi permis de mettre en évidence l’asymétrie de la tête. La méthode de création de modèles anthropométriques est plus adaptée à nos applications que les méthodes dans la littérature. L’analyse en trois dimensions permet d’obtenir des résultats qui ne sont pas visibles par les analyses 1D. Les connaissances acquises par cette étude sont utilisées pour la conception de différents produits vendus dans les magasins DECATHLON à travers le monde. / Anthropometry is the scientific field that studies human body dimensions (from the greek άνθρωπος (human) + μέτρον (measure)). Anthropometrical analysis is based actually on 1D measurements (head circumference, length, etc). However, the body’s morphological complexity requires 3D analysis. This is possible due to recent progress of 3D scanners. The objective of this study is to compare population’s anthropometry and use results to adapt sporting goods to user’s morphology. For this purpose, 3D worldwide measurement campaigns were realized and automated treatment algorithms were created in order to analyze the subjects’ point cloud. Based on image processing methods and on shape geometry, these algorithms detect anatomical landmarks, calculate 1D measurements, align subjects and create representative anthropometrical 3D models. In order to analyze morphological characteristics, different statistical methods including components’ analysis, were adapted for use in 3D space. The methods were applied in three body parts: the foot, the head and the bust. The morphological differences between and inside the populations were studied. For example, the difference in each point of the head, between Chinese and European head, was calculated. The statistics in three dimensions, permitted also to show the asymmetry of the head. The method to create anthropometrical models is more adapted to our applications than the methods used in the literature. The analysis in three dimensions, can give results that they are not visible from 1D analyses. The knowledge of this thesis is used for the conception of different products that they are sold in DECATHLON stores around the world.
147

The Best of Both Worlds: The Application of Traditional Animation Principles in 3D Animation Software

Harvey, Louise, n/a January 2007 (has links)
This research assesses the skills and knowledge necessary for the creation of animation in the 3D computer medium. It responds to the argument that students of this new form of animation must learn to apply principles and theories of animation that had their genesis in the early years of traditional, hand-drawn animation (Kroyer, 2002). Many industry notables argue for the use of traditional animation principles in 3D computer animation. John Lasseter, executive vice president at Pixar studios in the United States, represents one such example. He states that 'These principles were developed to make animation, especially character animation, more realistic and entertaining. These principles can and should be applied to 3D computer animation' (Lasseter 1987). The importance of animation principles in all animation mediums is stressed by Oscar-winning traditional animator Gene Deitch. He states that 'Every animated film made today uses those same basic principles developed at the Walt Disney studios during the 1930s. They still apply, no matter which technology is used' (2001). This research report examines the validity of this argument and identifies the tools, principles, and procedures that professional 3D animators are using. Central to this research is the dynamic of the contemporary relevance of traditional animation as an aesthetic, craft and economic entity. Most importantly this research considers how that dynamic might translate into the teaching of 3D animation courses. It is claimed that the findings of this research benefits 3D animation teachers, students, and those who employ them. To conduct on-site research with professional animators, this study enlisted the participation of a small number of animation studios in south-east Queensland, Australia by ensuring the protection of their Intellectual Property. Close observation of their working practices was made and numerous secondary sources of information (3D animation tutorials, books, DVDs, software manuals etc.) examined in order to locate the tools, processes, and principles that CG animators engaged. The findings were applied and critically assessed by means of a practical project (a seven-minute 3D-animated film) which was created concurrently with the research. Recommendations were formulated as to the most useful tools, processes, and principles for the student of computer animation by way of a revision of the existing Queensland College of Art syllabus for teaching computing animation. What follows is an account of the development and context of the project, the research methods applied, and critical analyses of the findings. The research concludes that it is necessary and advantageous to apply traditional animation skills to 3D computer work.
148

Arbetsprocessen i en 3d-produktion : En erfarenhetsbaserad reflektion kring arbetsprocessen i en storydriven 3d-kortfilms produktion

Nyman, Per January 2009 (has links)
Rapporten är en erfarenhetsbaserad reflektion över min praktiktid på 3d-produktionsföretaget Kaktus Film i Stockholm. Under min tid på företaget var jag med, från början till slut, i produktionen av en tysk musikvideo till en artist som heter Eisblume. Min roll i projektet med musikvideon var 3d-grafiker. Jag har primärt arbetat med tre olika saker; att skapa och animera blodådror som växer fram i olika miljöer, att skapa vattensimulationer och att färgmatcha och justera de renderade bilderna. Rapporten beskriver min kunskaps/arbetsprocess på Kaktus Film och de problem som uppstod i arbetet. Rapporten ger också en helhetsbild av arbetsprocessen i en storydriven kortfilms 3d-produktion. Arbetet i en sådan produktion beskrivs delvis utifrån min deltagande observation på Kaktus Film, men också utifrån litteratur inom området. En beskrivning av arbetsprocessen i en storydriven kortfilms 3d-produktion har skrivits parallellt med rapporten och finns bifogad som en bilaga till rapporten. Bilagan kompletterar den reflekterande texten för att ge en tydligare helhetsbild av en typisk produktion.Under min praktiktid på Kaktus Film kom jag att reflektera över att det finns så få kvinnor på 3d-produktionsföretagen. Jag beslutade då att utföra en mindre genusundersökning. Genusundersökningen behandlar frågor som kretsar kring könsfördelningen i 3d-branschen. Till exempel vad den ojämna könsfördelningen kan bero på. Genusundersökningen visar att var tredje person på en 3d-relaterad utbildning är kvinna, medan andelen anställda kvinnor i 3d-branschen uppskattas till endast 10 procent. Teorier om att den kulturella jantelagen ligger till grund för könsfördelningen diskuteras. Det visar sig också att den fördomsfulla uppfattningen, att män är bättre på tekniska uppgifter, gör sig starkt ihågkommen i 3d-branschen. Genusundersökningen börjar under kapitel 5.
149

En studie om arbetsprocess under praktik : Samt en fördjupande undersökning om kritik

Lowe Larsson, David January 2009 (has links)
Under två månader, februari - april 2009, har jag haft praktikplats på ett produktionsbolag i Göteborg. Jag har gjort praktik samtidigt som jag har genomfört en etnografisk studie av medarbetarna på företaget. Arbetet har företrädesvis varit att skapa grafiskt material för reklamfilm.   På min praktikplats har jag arbetat med grafiskt material. Jag har framför allt fått arbeta med programmet Maya (Autodesk Maya 2009) men också med andra programvaror som Nuke (The Foundry) och Photoshop (adobe). Arbetet har inneburit att arbeta med Maya och skapa 3D-objekt men även att göra saker som att rotoscopa i Nuke. Jag har företrädesviss modellerat, texturerat, animerat, shade’at, ljussatt, renderat, rotoscopat och keyat. Min praktik har varit mycket givande och lärorikt.   I denna rapport kommer jag att beskriva min arbetsprocess för att på så sätt ge läsaren en djupare inblick i hur arbetet på ett produktionsbolag fungerar.   Under min praktikperiod uppfattade jag skillnader i hur kritik ges och tas emot i skolmiljö kontra arbetslivet. Detta medförde att jag ville fördjupa mig inom detta vilket resulterade i min undersökning och under ett handledningstillfälle diskuterade jag och min handledare hur kritik fungerar i skolmiljö och arbetsmiljö. Denna diskussion resulterade i undersökningen där jag valde att intervjua personer med erfarenhet kring ämnet kritik. Jag berörde även området arbetsprocesser under mina intervjuer som jag anser har gjort min rapport bättre då den huvudsakligen handlar om just min egna arbetsprocess. I intervjuerna frågade jag till exempel om hur de gav och mottog kritik samt vilka kriterier som fanns när de granskade olika verk. Genom min intervjustudie om kritik får läsaren en djupare förståelse skillnaderna i arbetsliv och skola.   För mig har tiden under min praktik varit utvecklande och jag tror att min erfarenhet kan komma att främja andra studenter. De kommer i min rapport få inblickar i hur det är att vara på ett företag, samt hur och vad man kan få arbeta med där. Jag tror också att min undersökning om kritik kan gynna både studenter, skola och företag, då det kan vara svårt att implementera den form av kritik som ges i skolmiljö på det sätt kritik ges på en arbetsplats. Jag hoppas att min rapport kan ge upphov till vidare idéer om hur man kan utforma en mer förberedd skolutbildning inför arbetslivet.
150

En visuell teknik för nöjets skull? : 3D-formatets utveckling på vita duken

Rydahl, Linn January 2010 (has links)
Syftet med uppsatsen har varit att undersöka 3D-formatet som attraktion inom filmmediet och dess förändring över tid samt dess möjliga framtid. Inom detta undersöktes också hur det nya 3D-formatet (som i uppsatsen kallas det digitala 3D-formatet) har påverkats av tekniska och ekonomiska omständigheter. 3D-formatet har under uppsatsen jämförts med ljudet och färgens utveckling mot standard för att se ifall 3D-formatet följer en liknande riktning och själv håller på att gå över till en standard. Grunden i uppsatsen har legat på teorin av Tom Gunnings cinema of attraction och utifrån den teorin har analysen fokuserat på hur filmer från olika tidsperioder har används sig av 3D-formatet. Analysen har också granskat filmernas genrertillhörighet och dess användning av slogans. Resultatet var i korthet att 3D-formatet fortfarande är en attraktion men att den inte längre följer Gunnings teori. Numera är 3D-formatet invävt i narrationen genom att kameran och skådespelarnas agerande följer med i 3D-formatets rörelse. Innovationen pausar därför inte längre berättelsen för att visa sin attraktion. 3D-formatet följer både ljudet och färgens utveckling till vis del. Färgen är den innovationsom 3D-formatet mest påminner om. Precis som färgen, som använde sig av färg för att skilja mellan verklighet och dröm, har 3D-formatet även tagit del av detta berättargrepp. Möjligheten finns att 3D-formatets spridning ut i andra medier, precis som färgens spridning till televisionen, kan hjälpa 3D-formatet i dess väg att bli en standard inom filmmediet. Dockär 3D-formatet fortfarande låst i sin visuella attraktion och används mer för att visuellt underhålla än för att visuellt berätta. Det är både tekniska och ekonomiska omständigheter som samarbetat för att få 3D-formatet att återkomma i ett digitalt format. Ingen av dem kunde enskilt få fram innovationen. Vikten ligger på de tekniska omständigheterna i och med digitaliseringen som sker hos biograferna, men digitaliseringen i sig styrs både av tekniska och ekonomiska val och 3D-formatet är främst en ekonomisk hjälp för biograferna att göra digitaliseringen. 3D-formatet är därmed mer en ekonomisk hjälp än en teknisk utbyggnad av filmmediet.

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