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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.
61

Developing a Computer System for the Generation of Unique Wrinkle Maps for Human Faces. Generating 2D Wrinkle Maps using Various Image Processing Techniques and the Design of 3D Facial Ageing System using 3D Modelling Tools.

Mehdi, Ali January 2011 (has links)
Facial Ageing (FA) is a very fundamental issue, as ageing in general, is part of our daily life process. FA is used in security, finding missing children and other applications. It is also a form of Facial Recognition (FR) that helps identifying suspects. FA affects several parts of the human face under the influence of different biological and environmental factors. One of the major facial feature changes that occur as a result of ageing is the appearance and development of wrinkles. Facial wrinkles are skin folds; their shapes and numbers differ from one person to another, therefore, an advantage can be taken over these characteristics if a system is implemented to extract the facial wrinkles in a form of maps. This thesis is presenting a new technique for three-dimensional facial wrinkle pattern information that can also be utilised for biometric applications, which will back up the system for further increase of security. The procedural approaches adopted for investigating this new technique are the extraction of two-dimensional wrinkle maps of frontal human faces for digital images and the design of three-dimensional wrinkle pattern formation system that utilises the generated wrinkle maps. The first approach is carried out using image processing tools so that for any given individual, two wrinkle maps are produced; the first map is in a binary form that shows the positions of the wrinkles on the face while the other map is a coloured version that indicates the different intensities of the wrinkles. The second approach of the 3D system development involves the alignment of the binary wrinkle maps on the corresponding 3D face models, followed by the projection of 3D curves in order to acquire 3D representations of the wrinkles. With the aid of the coloured wrinkle maps as well as some ageing parameters, simulations and predictions for the 3D wrinkles are performed.
62

Rekonstruktion av Ör kyrkas tidigmedeltida takkonstruktion / Reconstruction of Ör church early medieval roof structure

Lorentsson, Jimmy, Forssgren, David January 2022 (has links)
During an inventory of Ör church’s roof structure in 2021, it was discovered that the roofstructure above the church’s nave contains a large amount of reused structural parts froman earlier roof structure. The reused structural parts are most likely originated from Örchurch’s early medieval roof structure.This thesis is an attempt to reconstruct the early medieval roof structure with the use of3D-laser scanning. The goal is to present a possible shape and 3D-model of the earlymedieval roof structure. The existing roof structure will also be documented. One aim ofthe thesis is to develop and evaluate the method of using 3D-laser scanning for thispurpose.The reconstruction resulted in eight different shapes and 3D-models of the early medievalroof structure. The documentation of the existing roof structure above the nave resulted inupdated section, plan and detailed drawings.The method of using 3D-laser scanning gave a detailed point cloud of the existing roofstructure. The point cloud had low density points in certain parts of the roof structurewhich is a consequence from the implementation of the 3D laser scanning. For thismethod a field study and planning in advance is recommended for best possible result.
63

Modellering och robusthetsanalys med parametrisk design : Effektivare visualisering av alternativa lastvägar vid bortfall av pelare

Kayhan, Özge, Mohamed, Zahra January 2020 (has links)
Today, 3D modelling and structural analysis of buildings are performed in various software. Collaboration between various software is common today but breaks the flow in the construction design phase. To achieve an uninterrupted flow in the construction design phase, a constellation of modelling and structural analysis is needed in a single software. To enable a constellation, there are today many developed digital methods for this.Parametric design is a digital method that is mostly used to handle complex shapes. In recent years, the parametric design has evolved even more and the algorithmic thinking in parametric design provides opportunities for performing structural analyses. The development includes various plug-in programs that have structural analysis capabilities. However, this degree project emphasizes that this can be achieved without a plug-in program that has structural analysis capabilities. With only one visualization program and a plug-in that handles visual programming, the ability to produce what is to be visualized with a script arises.The structural analysis in this thesis includes robustness analysis that is important in the context of progressive collapse, and only the alternative load path method is considered. Progressive collapse is an important analysis for buildings that arise due to known or unknown accident loads. To increase the redundancy of the bearing structure, the alternative load path method can be used, which is a branch under unknown accident loads.Robustness analysis is a time-consuming process and automation can make this more efficient. With parameter-driven modelling and robustness analysis, the constructor can indicate at an early stage possible structure failure before the building is completed. Early action also leads to a reduction in waste of material resources.The alternative load path method provides the possibility to analyze whether the building receives alternate load path in the event of loss of load-bearing elements. This research report analyses column loss. Automated visualization of alternate load path enables to be able to analyze the load redistribution after the loss of column.Today some buildings are at risk against the progressive collapse, people's lives and health are therefore at risk when all or part of the building collapses. That is why efficiency is needed. The research report showed that the script automated the modelling and robustness analysis of buildings. Two different loss scenarios were analyzed and the authors found different updated loading areas and load redistribution.
64

Spend time, get paid. : BIM with 3D modelling for a small construction enterprise, a study of a small construction enterprise. / Tid ut, pengar in. : BIM med 3D-modellering för mindre utförande entreprenörer inom byggbranschen.

Swanepoel, Hugo, Teiner, Henrik January 2021 (has links)
Building Information Modelling (BIM) is currently widely used within the architecture engineering and construction (AEC) industry. However, BIM and specifically 3D-modelling is mainly only used by large scale construction enterprises while smaller and medium sized construction enterprises are still using outdated methods such as 2D-drawings. This thesis is carried out in cooperation with Multibygg Entreprenad i Stockholm AB, a small sized construction enterprise. The purpose of this thesis is to understand their perception on the usage and implementation of 3D modelling, what the reasons are for not having already invested in 3D modelling and, finally, to understand how 3D modelling would relate to the core process. The work consists of a literature review to give a better understanding of the chosen subject. A case study is also included and is limited to analysing the organisation of Multibygg. Furthermore, interviews were conducted with members associated with the company either directly or indirectly based on the type of work that is conducted. The results show that the small sized construction enterprise has a positive perspective on the usage of 3D modelling but that implementing it is difficult to realise due to expensive subscription costs and a lack of usefulness to the small construction enterprise. / Building Information Modelling (BIM) används mycket inom byggbranschen idag. Däremot används BIM, och specifikt 3D-modellering, främst av större entreprenörer medan mindre utförande entreprenörer fortfarande använder sig av utdaterade metoder som 2D-ritningar. Denna kandidatuppsats är utförd med hjälp av Multibygg Entreprenad i Stockholm AB, en mindre utförande entreprenör. Syftet med denna uppsats är att förstå deras uppfattning om 3D-modellering, vilka faktorer som har hindrat en investering i 3D-modellering och hur 3D-modellering kan bidra till deras kärnprocess. Arbetet består av en litteraturöversikt för att ge en djupare förståelse av det valda ämnet. En fallstudie är också inkluderad för att analysera Multibygg som organisation. Som empiri samlades intervjuer med aktörer som relaterar till Multibygg baserat på den typen av arbetet som utförs. Resultaten visar att den mindre utförande entreprenören har en positiv syn på användningen av 3D-modellering, men att det är svårt att implementera den på grund av höga abonnemangskostnader och att det kommer bidra för lite till deras projekt och kärnprocess.
65

Experimental study of oil coking problem and contribution to the modelling of heat transfer in turbochargers

Rodriguez Usaquén, Yuly Tatiana 22 February 2019 (has links)
[ES] The automotive industry represents one of the most important sectors in the world. Given its socio-economic influence, research is aimed at reducing fuel consumption and emissions. Turbochargers provide several benefits including increased power for a given engine size, improved fuel economy and reduced emissions. The turbocharger is an important piece for the new generation of engines that must comply with the Euro 6 or in the U.S. Tier 3 vehicle emissions and fuel standard program. As more effort is made to increase efficiencies and reduce emissions, the complexity of the system increases. The high rotational speeds, pulsating flow conditions and high temperature differences between working fluids (exhaust gases, compressed air, lubricating oil, coolant fluids) make the turbo-charging a challenging task. Numerical simulation opens a range of possibilities to study the performance, efficiency and design of components in the turbocharger, but requires continued accuracy refinements. In this thesis, a great effort has been made to improve the overall understanding of the different physical phenomena that occur inside the turbocharger. Both, experimental and modelling efforts have been made to understand the thermal behaviour of the turbocharger under engine start/stop conditions. After state-of-the-art review of thermal studies and heat transfer simulation codes, this work presents an extensive experimental testing campaign that includes a thermal characterization of the turbocharger in stationary and transient conditions. Subsequently, several turbochargers were measured to assess the consequences that degraded oils can generate in the bearing system during endurance tests of oil-coking. To minimize the possibilities of coke formation, some theoretical studies were done. First, a 1D turbocharger model was used in GT-PowerTM for a detailed study of the temperature rise in the central housing during an engine hot-stop. The simulated cooling strategies aims to find an optimal in terms of minimizing extra energy consumption per K housing temperature reduction. After, a 2D radial model is proposed as improvement of an existing one-dimensional model developed at CMT - Universitat Politècnica de València. Aiming for a low computational cost, the radial model was developed to be compatible with fast one-dimensional engine simulations. Later, a detailed solution of heat fluxes was made by means of CFD using a 3D design of the turbocharger's central housing. The 3D model improved the results when temperature of the bearings/shaft is required. Additionally, thermal properties within the turbocharger can be obtained and therefore a reduction of the experimental tasks in the thermohydraulic test bench. Both 2D and 3D models were validated using experimental data, demonstrating predictive accuracy improvements on the results of previous models. / [CA] La industria automotriz representa uno de los sectores más importantes del mundo. Dada su influencia socioeconómica, la investigación está destinada a reducir el consumo de combustible y las emisiones. Los turbocompresores ofrecen varios beneficios, entre ellos, mayor potencia para un tamaño de motor determinado, mejor economía de combustible y reducción de emisiones. El turbocompresor es una pieza importante para la nueva generación de motores que deben cumplir con la normativa Euro 6 o en el programa estándar de emisiones y combustible de los EE. UU. Tier 3. A medida que se hacen más esfuerzos para aumentar la eficiencia y reducir las emisiones, la complejidad del sistema aumenta. Las altas velocidades de rotación, las condiciones de flujo pulsante y las altas diferencias de temperatura entre los fluidos de trabajo (gases de escape, aire comprimido, aceite lubricante, fluidos refrigerantes) hacen que la turbocarga sea una tarea desafiante. La simulación numérica abre un rango de posibilidades para estudiar el rendimiento, la eficiencia y el diseño de los componentes en el turbocompresor, pero requiere continuos refinamientos de precisión. En esta tesis, se ha hecho un gran esfuerzo para mejorar la comprensión global de los diferentes fenómenos físicos que ocurren al interior del turbocompresor. Se han hecho esfuerzos experimentales y de modelado para comprender el comportamiento térmico del turbocompresor en condiciones de arranque/parada del motor. Luego de una revisión de los estudios térmicos y de los códigos de simulación de transferencia de calor, éste trabajo presenta una extensa campaña de pruebas experimentales que incluye una caracterización térmica del turbocompresor en condiciones estacionarias y transitorias. Posteriormente, se midieron varios turbocompresores para evaluar las consecuencias que los aceites degradados pueden generar en el sistema de rodamientos durante pruebas de resistencia de coque de aceite. Para minimizar las posibilidades de formación de coque, se realizaron algunos estudios teóricos. En primer lugar, se usó un modelo de turbocompresor 1D en GT-PowerTM para un estudio detallado del aumento de temperatura de la carcasa central del turbocompresor durante un paro en caliente del motor. Las estrategias de enfriamiento simuladas apuntan a encontrar un óptimo en términos de minimizae el consumo de energía extra por reducción de la temperatura de la carcasa en Kelvin. Posteriormente, se propone un modelo radial 2D como mejora de un modelo unidimensional existente desarrollado en la CMT - Universitat Politècnica de València. Con el objetivo de conseguir un bajo costo computacional, el modelo radial 2D se desarrolló para ser compatible con simulaciones unidimensionales rápidas de motor. Después, se realizó una solución detallada de los flujos de calor mediante CFD utilizando un diseño 3D de la carcasa central del turbocompresor. El modelo 3D mejora los resultados cuando se requiere la temperatura de los cojinetes/eje. Además, con ésta campaña de CFD se pueden obtener propiedades térmicas dentro del turbocompresor y, por lo tanto, una reducción de las tareas experimentales en el banco de pruebas termohidráulico. Ambos modelos 2D y 3D fueron validados utilizando datos experimentales, demostrando mejoras de precisión de predicción sobre los resultados de modelos anteriores. / [EN] La indústria automotriu representa un dels sectors més importants del món. Donada la seua influència socioeconòmica, la investigació està destinada a reduir el consum de combustible i les emissions. Els turbocompressors oferixen diversos beneficis, entre ells, major potència per a una grandària de motor determinat, millor economia de combustible i reducció d'emissions. El turbocompressor és una peça important per a la nova generació de motors que han de complir amb la normativa Euro 6 o en el programa estàndard d'emissions i combustible dels EE. UU. Tier 3. A mesura que es fan més esforços per a augmentar l'eficiència i reduir les emissions, la complexitat del sistema augmenta. Les altes velocitats de rotació, les condicions de flux polsen-te i les altes diferències de temperatura entre els fluids de treball (gasos de fuga, aire comprimit, oli lubricant, fluids refrigerants) fan que la turbocarga siga una tasca desafiador. La simulació numèrica obri un rang de possibilitats per a estudiar el rendiment, l'eficiència i el disseny dels components en el turbocompressor, però requerix continus refinaments de precisión. En aquesta tesi, s'ha fet un gran esforç per a millorar la comprensió global dels diferents fenòmens físics que ocorren a l'interior del turbocompressor. S'han fet esforços experimentals i de modelatge per a comprendre el comportament tèrmic del turbocompressor en condicions d'arranque/parada del motor. Després d'una revisió dels estudis tèrmics i dels codis de simulació de transferència de calor, este treball presenta una extensa campanya de proves experimentals que inclou una caracterització tèrmica del turbocompressor en condicions estacionàries i transitòries. Posteriorment, es van mesurar uns quants turbocompressors per a avaluar les conseqüències que els olis degradats poden generar en el sistema de rodaments durant proves de resistència de coc d'aceite. Per a minimitzar les possibilitats de formació de coc, es van realitzar alguns estudis teòrics. En primer lloc, es va usar un model de turbocompressor 1D en GT- Power \textsuperscript{TM} per a un estudi detallat de l'augment de temperatura de la carcassa central del turbocompressor durant una desocupació en calent del motor. Les estratègies de refredament simulades apunten a trobar un òptim en termes de minimizae el consum d'energia extra per reducció de la temperatura de la carcassa en Kelvin. Posteriorment, es proposa un model radial 2D com a millora d'un model unidimensional existent desenrotllat en la CMT - Universitat Politècnica de València. Amb l'objectiu d'aconseguir un baix cost computacional, el model radial 2D es va desenrotllar per a ser compatible amb simulacions unidimensionals ràpides de motor. Después, es va realitzar una solució detallada dels fluxos de calor per mitjà de CFD utilitzant un disseny 3D de la carcassa central del turbocompressor. El model 3D millora els resultats quan es requerix la temperatura dels cojinetes/eje. A més, amb esta campanya de CFD es poden obtindre propietats tèrmiques dins del turbocompressor i, per tant, una reducció de les tasques experimentals en el banc de proves termohidráulico. Ambdós models 2D i 3D van ser validats utilitzant dades experimentals, demostrant millores de precisió de predicció sobre els resultats de models anteriores. / Rodriguez Usaquén, YT. (2019). Experimental study of oil coking problem and contribution to the modelling of heat transfer in turbochargers [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/117314
66

Roadmark reconstruction from stereo-images acquired by a ground-based mobile mapping system

Soheilian Khorzoughi, Bahman 01 April 2008 (has links) (PDF)
Despite advances in ground-based Mobile Mapping System (MMS), automatic feature reconstruction seems far from being reached. In this thesis, we focus on 3D roadmark reconstruction from images acquired by road looking cameras of a MMS stereo-rig in dense urban context. A new approach is presented, that uses 3D geometric knowledge of roadmarks and provides a centimetric 3D accuracy with a low level of generalisation. Two classes of roadmarks are studied: zebra-crossing and dashed-lines. The general strategy consists in three main steps. The first step provides 3D linked-edges. Edges are extracted in the left and right images. Then a matching algorithm that is based on dynamic programming optimisation matches the edges between the two images. A sub-pixel matching is computed by post processing and 3D linked-edges are provided by classical photogrammetric triangulation. The second step uses the known specification of roadmarks to perform a signature based filtering of 3D linked-edges. This step provides hypothetical candidates for roadmark objects. The last step can be seen as a validation step that rejects or accepts the candidates. The validated candidates are finely reconstructed. The adopted model consists of a quasi parallelogram for each strip of zebra-crossing or dashed-line. Each strip is constrained to be flat but the roadmark as a whole is not planar. The method is evaluated on a set of 150 stereo-pairs acquired in a real urban area under normal traffic conditions. The results show the validity of the approach in terms of robustness, completeness and geometric accuracy. The method is robust and deals properly with partially occluded roadmarks as well as damaged or eroded ones. The detection rate reaches 90% and the 3D accuracy is about 2-4 cm. Finally an application of reconstructed roadmarks is presented. They are used in georeferencing of the system. Most of the MMSs use direct georeferencing devices such as GPS/INS for their localisation. However in urban areas masks and multi-path errors corrupt the measurements and provide only 50 cm accuracy. In order to improve the localisation quality, we aim at matching ground-based images with calibrated aerial images of the same area. For this purpose roadmarks are used as matching objects. The validity of this method is demonstrated on a zebra-crossing example
67

Optimisation évolutionnaire multi-objectif parallèle : application à la combustion Diesel / Multi-objective parallel evolutionary algorithms : Application to Diesel Combustion

Yagoubi, Mouadh 03 July 2012 (has links)
Avec la sévérisation des réglementations environnementales sur les émissions polluantes (normes Euro) des moteurs d'automobiles, la nécessité de maitriser les phénomènes de combustion a motivé le développement de la simulation numérique comme outil d'aide à la conception. Tenant compte de la complexité des phénomènes à modéliser, et de l'antagonisme des objectifs à optimiser, l'optimisation évolutionnaire multi-objectif semble être la mieux adaptée pour résoudre ce type de problèmes. Cependant, l'inconvénient principal de cette approche reste le coût très élevé en termes de nombre d'évaluations qui peut devenir très contraignant dans le contexte des optimisations réelles caractérisées par des évaluations très coûteuseL'objectif principal de ce travail de thèse est de réduire le coût global des optimisations du monde réel, en explorant la parallélisation des algorithmes évolutionnaires multi-objectifs, et en utilisant les techniques de réduction du nombre d'évaluations (méta-modèles).Motivés par le phénomène d'hétérogénéité des coûts des évaluations, nous nous proposons d'étudier les schémas d'évolution stationnaires asynchrones dans une configuration parallèle de type « maître-esclave ». Ces schémas permettent une utilisation plus efficace des processeurs sur la grille de calcul, et par conséquent de réduire le coût global de l'optimisation.Ce problème a été attaqué dans un premier temps d'un point de vue algorithmique, à travers une adaptation artificielle des algorithmes évolutionnaires multi-objectifs au contexte des optimisations réelles caractérisées par un coût d'évaluation hétérogène. Dans un deuxième temps, les approches développées et validées dans la première partie sur des problèmes analytiques, ont été appliquées sur la problématique de la combustion Diesel qui représente le contexte industriel de cette thèse. Dans ce cadre, deux types de modélisations ont été utilisés: la modélisation phénoménologique 0D et la modélisation multidimensionnelle 3D. La modélisation 0D a permis par son temps de retour raisonnable (quelques heures par évaluation) de comparer l'approche stationnaire asynchrone avec celle de l'état de l'art en réalisant deux optimisations distinctes. Un gain de l'ordre de 42 % a été réalisé avec l'approche stationnaire asynchrone. Compte tenu du temps de retour très coûteux de la modélisation complète 3D (quelques jours par évaluation), l'approche asynchrone stationnaire déjà validée a été directement appliquée. L'analyse physique des résultats a permis de dégager un concept intéressant de bol de combustion permettant de réaliser un gain en termes d'émissions polluantes. / In order to comply with environmental regulations, automotive manufacturers have to develop efficient engines with low fuel consumption and low emissions. Thus, development of engine combustion systems (chamber, injector, air loop) becomes a hard task since many parameters have to be defined in order to optimize many objectives in conflict. Evolutionary Multi-objective optimization algorithms (EMOAs) represent an efficient tool to explore the search space and find promising engine combustion systems. Unfortunately, the main drawback of Evolutionary Algorithms (EAs) in general, and EMOAs in particular, is their high cost in terms of number of function evaluations required to reach a satisfactory solution. And this drawback can become prohibitive for those real-world problems where the computation of the objectives is made through heavy numerical simulations that can take hours or even days to complete.The main objective of this work is to reduce the global cost of real-world optimization, using the parallelization of EMOAs and surrogate models.Motivated by the heterogeneity of the evaluation costs observed on real-world applications, we study asynchronous steady-state selection schemes in a master-slave parallel configuration. This approach allows an efficient use of the available processors on the grid computing system, and consequently reduces the global optimization cost.In the first part of this work, this problem has been studied in an algorithmical point of view, through an artificial adaptation of EMOAs to the context of real-world optimizations characterized by a heterogeneous evaluation cost.In the second part, the proposed approaches, already validated on analytical functions, have been applied on the Diesel combustion problem, which represents the industrial context of this thesis. Two modelling approaches have been used: phenomenological modelling (0D model) and multi-dimensional modelling (3D model).The 0D model allowed us, thanks to its reasonable evaluation cost (few hours per evaluation) to compare the asynchronous steady-state approach with the standard generational one by performing two distinct optimizations. A gain of 42 % was observed with the asynchronous steady-state approach.Given the very high evaluation cost of the full 3D model, the asynchronous steady-state approach already validated has been applied directly. The physical analysis of results allowed us to identify an interesting concept of combustion bowl with a gain in terms of pollutant emissions.
68

Rastreamento de componentes conexas em vídeo 3D para obtenção de estruturas tridimensionais / Tracking of connected components from 3D video in order to obtain tridimensional structures

Pires, David da Silva 17 August 2007 (has links)
Este documento apresenta uma dissertação sobre o desenvolvimento de um sistema de integração de dados para geração de estruturas tridimensionais a partir de vídeo 3D. O trabalho envolve a extensão de um sistema de vídeo 3D em tempo real proposto recentemente. Esse sistema, constituído por projetor e câmera, obtém imagens de profundidade de objetos por meio da projeção de slides com um padrão de faixas coloridas. Tal procedimento permite a obtenção, em tempo real, tanto do modelo 2,5 D dos objetos quanto da textura dos mesmos, segundo uma técnica denominada luz estruturada. Os dados são capturados a uma taxa de 30 quadros por segundo e possuem alta qualidade: resoluções de 640 x 480 pixeis para a textura e de 90 x 240 pontos (em média) para a geometria. A extensão que essa dissertação propõe visa obter o modelo tridimensional dos objetos presentes em uma cena por meio do registro dos dados (textura e geometria) dos diversos quadros amostrados. Assim, o presente trabalho é um passo intermediário de um projeto maior, no qual pretende-se fazer a reconstrução dos modelos por completo, bastando para isso apenas algumas imagens obtidas a partir de diferentes pontos de observação. Tal reconstrução deverá diminuir a incidência de pontos de oclusão (bastante comuns nos resultados originais) de modo a permitir a adaptação de todo o sistema para objetos móveis e deformáveis, uma vez que, no estado atual, o sistema é robusto apenas para objetos estáticos e rígidos. Até onde pudemos averiguar, nenhuma técnica já foi aplicada com este propósito. Este texto descreve o trabalho já desenvolvido, o qual consiste em um método para detecção, rastreamento e casamento espacial de componentes conexas presentes em um vídeo 3D. A informação de imagem do vídeo (textura) é combinada com posições tridimensionais (geometria) a fim de alinhar partes de superfícies que são vistas em quadros subseqüentes. Esta é uma questão chave no vídeo 3D, a qual pode ser explorada em diversas aplicações tais como compressão, integração geométrica e reconstrução de cenas, dentre outras. A abordagem que adotamos consiste na detecção de características salientes no espaço do mundo, provendo um alinhamento de geometria mais completo. O processo de registro é feito segundo a aplicação do algoritmo ICP---Iterative Closest Point---introduzido por Besl e McKay em 1992. Resultados experimentais bem sucedidos corroborando nosso método são apresentados. / This document presents a MSc thesis focused on the development of a data integration system to generate tridimensional structures from 3D video. The work involves the extension of a recently proposed real time 3D video system. This system, composed by a video camera and a projector, obtains range images of recorded objects using slide projection of a coloured stripe pattern. This procedure allows capturing, in real time, objects´ texture and 2,5 D model, at the same time, by a technique called structured light. The data are acquired at 30 frames per second, being of high quality: the resolutions are 640 x 480 pixels and 90 x 240 points (in average), respectively. The extension that this thesis proposes aims at obtaining the tridimensional model of the objects present in a scene through data matching (texture and geometry) of various sampled frames. Thus, the current work is an intermediary step of a larger project with the intent of achieving a complete reconstruction from only a few images obtained from different viewpoints. Such reconstruction will reduce the incidence of occlusion points (very common on the original results) such that it should be possible to adapt the whole system to moving and deformable objects (In the current state, the system is robust only to static and rigid objects.). To the best of our knowledge, there is no method that has fully solved this problem. This text describes the developed work, which consists of a method to perform detection, tracking and spatial matching of connected components present in a 3D video. The video image information (texture) is combined with tridimensional sites (geometry) in order to align surface portions seen on subsequent frames. This is a key step in the 3D video that may be explored in several applications such as compression, geometric integration and scene reconstruction, to name but a few. Our approach consists of detecting salient features in both image and world spaces, for further alignment of texture and geometry. The matching process is accomplished by the application of the ICP---Iterative Closest Point---algorithm, introduced by Besl and McKay in 1992. Succesful experimental results corroborating our method are shown.
69

Les nouveaux arts de la mémoire : topiques digitales. La réactualisation de l’ars memoriae grâce à l’infographie tridimensionnelle / The new arts of memory : digital topics. How 3D computer graphics are helping rekindle the ars memoriae

Aubert, Donatien 15 March 2019 (has links)
Au-delà des outils d’analyse statistique traditionnellement mobilisés par les chercheurs en humanités numériques, il existe de nombreux instruments de visualisation (bases de données 3D, moteurs de jeu vidéo, réalité virtuelle et augmentée, etc.) qui ont gagné ces dernières années une importance croissante, ceux-là permettant de spatialiser les connaissances de façon intuitive, de donner à voir des vestiges en lien avec les enquêtes humanistes ou encore de toucher un public dépassant le strict milieu universitaire. Cette thèse a pour but de préciser sur la base de quels modèles heuristiques et épistémologiques, les ingénieurs travaillant dans le domaine des interactions homme-machine ont pensé ces dispositifs. En Europe et jusqu’à l’époque baroque, plusieurs méthodes, désignées du nom d’arts de la mémoire, reposant sur l’immersion dans des espaces mentaux, avaient été mobilisées pour organiser les connaissances. Leur centralité dans la vie intellectuelle leur a donné une postérité double : elles ont structuré tant la manière de penser l’organisation des savoirs (logique et computation) que de les donner à voir (avènement du paradigme perspectif et de la muséologie). Cet héritage hybride les a constituées comme des repères pour le développement des nouveaux médias, notamment de l’infographie tridimensionnelle. Pour saisir les enjeux socio-économiques et esthétiques liés à l’utilisation de ces technologies dans le champ universitaire, leur mise au point dans les secteurs industriels du cinéma et du jeu vidéo, qui ont nourri leur évolution, est resituée dans la thèse. Cette enquête permet de définir des prescriptions utiles à leur déploiement au sein des humanités numériques. / Beyond the instruments of statistical analysis enlisted by researchers working in the field of digital humanities, a growing number of visual and spatial tools (3D databases, video game engines, virtual and augmented reality, etc.) have gained in interest over the past few years. These new approaches allow for the spatialized presentation of knowledge in novel and intuitive ways that increasingly appeal to a public beyond academia. The goal of this thesis is to pinpoint and explore the various heuristic and epistemological models engineers working in the field of human-computer interaction have used to develop these tools. Up until the Baroque period in Europe, a suite of methods grouped under the rubric of “the arts of memory” relied on similar modes of spatialization of immersive mental spaces in order to activate memory and to organize knowledge. The centrality of these arts in the formation of intellectual life has granted them a double posterity: they at once structured the way one organized knowledge – thus becoming instrumental in the refinement of logic and computation; while also serving as means to exhibit and present knowledge – allowing for the advent of the perspective paradigm and museology. This hybrid heritage establishes the arts of memory as landmarks for the further development of new media, and notably computer-generated images. To understand the stakes involved with the use of these technologies in scholarly practice, this thesis also addresses how the film and video game industries gradually shaped their evolution. Finally, this inquiry provides useful prescriptions for their deployment within the growing interdisciplinary field of digital humanities.
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From Matter to Data and Back Again : Enabling Agency through Digital Fabrication

Hansson, Mikael January 2018 (has links)
Digital fabrication technologies such as 3D printers entail a radical change to the traditional consumer-producer paradigm. Combined with other recent developments, self-styled Makers design and fabricate sophisticated devices and interactive technologies that would otherwise never have existed. However, stopping the uninitiated novice from making use of this potential is complex CAD software, and a high barrier to entry. In this study a series of workshops explore the potential of combining traditional handicraft materials – such as clay, paper and fabric – with 3D scanning to enable novices to work with 3D printers. Based on the results a set of instruction were created detailing the process of making three types of practical objects, covering the entire process from the making and subsequent 3D scanning of a physical object, to the software clean-up and final 3D printing. The results suggest that whilst the explored method can enable novices to create 3D printable models, a certain mindset is required for the novice to do so effectively. / Innovation +

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