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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.
11

Evaluating Visual Quality of Secondary Motion Simulation Techniques : A Survey on Stylized 3D Game Character Cloth and Hair

Burman, Adam January 2022 (has links)
Background. Secondary motion is a principle of animation, it is movement that occurs as a result of other movement, such as swinging hair or clothes. In 3D animation, such as in games, it is often simulated instead of animated manually. In game projects with time limitations, it can be interesting to know to what degree these simulations impact the visual quality in order to decide whether they should be prioritized. It is also interesting to know how the results of various methods compare to each other. To simulate in real-time means that physics simulations are running during gameplay. Baked animations on the other hand are simulations that have already been processed and saved as animation data, they are less dynamic but also less performance intensive. Objectives. The aim of this thesis is to evaluate the impact of three sets of animations by conducting a survey where each set is compared. The three sets are: animations that feature real-time simulations, baked simulations and ones without simulation. The goal is to acquire a metric from the comparisons that can give an insight to the visual quality impact of each method. Methods. Three animation sets were created. Then, a survey was conducted using a questionnaire that featured side by side video comparisons of the animation sets. The videos featured a stylized character running, walking, or jumping through an empty environment. Pairwise similarity judgements were done by asking the participants to rate each video compared to each other. The results from the questionnaire were analyzed using a method that is a part of the analytical hierarchy process. The data from each comparison was averaged, put into pairwise comparison matrices, and then used to calculate priority vectors. The level of consistency of the comparisons were also calculated. Results. The priority vectors show the ratios of how each animation set were preferred compared to each other. In the priority vector for all animations combined, the set without simulations ranked at twenty-four percent, the real-time set ranked at thirty-three percent and the baked set ranked the highest at forty-three percent. The comparisons were calculated to have a very high consistency, which strengthens the result. Conclusions. The results show the impact that adding simulated secondary motion has. The simulations appear to improve the visual quality, but the margin is not extreme. The calculated ratios could be used to argue for or against a game project’s prioritization of secondary motion simulations depending on the project’s time constraints and access to preexisting methods of simulation. It should be noted that the format of video comparisons did not showcase all the advantages of each method such as creation accessibility, technical performance or dynamicity. As such, it is uncertain how fair the comparisons of the baked and real-time simulations are in a more general sense. Nevertheless, the results are considered to give at least a partial insight into how these methods compare.
12

Stochastic Modelling and Analysis for Bridges under Spatially Varying Ground Motions

Zhang, Deyi January 2013 (has links)
Earthquake is undoubtedly one of the greatest natural disasters that can induce serious structural damage and huge losses of properties and lives. The resulting destructive consequences not only have made structural seismic analysis and design much more important but have impelled the necessity of more realistic representation of ground motions, such as inclusion of ground motion spatial variations in earthquake modelling and seismic analysis and design of structures. Recorded seismic ground motions exhibit spatial variations in their amplitudes and phases, and the spatial variabilities have an important effect on the responses of structures extended in space, such as long span bridges. Because of the multi-parametric nature and the complexity of the problems, the development of specific design provisions on spatial variabilities of ground motions in modern seismic codes has been impeded. Eurocode 8 is currently the only seismic standard worldwide that gives a set of detailed guidelines to explicitly tackle spatial variabilities of ground motions in bridge design, providing both a simplified design scheme and an analytical approach. However, there is gap between the code-specified provisions in Eurocode 8 and the realistic representation of spatially varying ground motions (SVGM) and the corresponding stochastic vibration analysis (SVA) approaches. This study is devoted to bridge this gap on modelling of SVGM and development of SVA approaches for structures extended in space under SVGM. A complete and realistic SVGM representation approach is developed by accounting for the incoherence effect, wave-passage effect, site-response effect, ground motion nonstationarity, tridirectionality, and spectra-compatibility. This effort brings together various aspects regarding rational seismic scenarios determination, comprehensive methods of accounting for varying site effects, conditional modelling of SVGM nonstationarity, and code-specified ground motion spectra-compatibility. A comprehensive, systematic, and efficient SVA methodology is derived for long span structures under tridirectional nonstationary SVGM. An absolute-response-oriented scheme of pseudo-excitation method and an improved high precision direct integration method are proposed to reduce the enormous computational effort of conventional nonstationary SVA. A scheme accounting for tridirectional varying site-response effect is incorporated in the nonstationary SVA scheme systematically. The proposed highly efficient and accurate SVA approach is implemented and verified in a general finite element analysis platform to make it readily applicable in SVA of complex structures. Based on the proposed SVA approach, parametric studies of two practical long span bridges under SVGM are conducted. To account for spatial randomness and variability of soil properties in soil-structure interaction analysis of structures under SVGM, a meshfree-Galerkin approach is proposed within the Karhunen-Loeve expansion scheme for representation of spatial soil properties modelled as a random field. The meshfree shape functions are proposed as a set of basis functions in the Galerkin scheme to solve integral equation of Karhunen-Loeve expansion, with a proposed optimization scheme in treating the compatibility between the target and analytical covariance models. The accuracy and validity of the meshfree-Galerkin scheme are assessed and demonstrated by representation of covariance models for various homogeneous and nonhomogeneous spatial fields. The developed modelling approaches of SVGM and the derived analytical SVA approaches can be applied to provide more refined solutions for quantitatively assessing code-specified design provisions and developing new design provisions. The proposed meshfree-Galerkin approach can be used to account for spatial randomness and variability of soil properties in soil-structure interaction analysis.
13

Evaluation of a Motion Simulation Platform for Vestibulo-Ocular Research / Utvärdering av en rörelsesimuleringsplatform för vestibulo-okulär forskning

Lundberg, Simon January 2014 (has links)
The vestibuloocular reflex can be manually elicited by tilting or rotating the head. Manual techniques serve their purpose well and is the golden standard in the clinical work, but they lack control of velocity and movement pattern. However, motion simulation platforms enable automatic control of both velocity and movement pattern. One motion simulation platform, named BIRGIT, has been built at the Department of Clinical Neurosciences at Karolinska Institutet but has not yet been in service and require a performance evaluation. The objectives with this thesis is to evaluate the accuracy and precision of BIRGIT and evaluate how bodyweight and movement direction impact the performance. The thesis also evaluate whether it is possible to stabilize the head of the patient during the acceleration phase. Repeated measurements of acceleration with different loads, desired ac- celeration, direction and motion type (rotational and translational), are per- formed. Dummies are used to simulate bodyweight in the performance study and real persons are used in the head stabilization study. Analysis of variance (ANOVA) is the main statistical tool. The results suggest that the platform does not perform equally at dif- ferent load or directions and that there is a bias between desired and true acceleration. The main problems are an inclination of the rails, upon which the chair is mounted, that causes differences between directions and an un- desirable performance characteristic for rotational motions. The stabilization study suggest that the head can be stabilized. / Den vestibulo-okul ̈ara reflexen kan framkallas genom att manuellt rotera eller rycka p ̊a huvudet. Att manuellt framkalla reflexen fungerar i de flesta sam- manhang va ̈l och a ̈r standard i m ̊anga underso ̈kningar. Dock g ̊ar det inte att till fullo kontrollera vare sig hastighet eller ro ̈relsebana perfekt. Emellertid g ̊ar detta att kontrollera genom att anva ̈nda sig av en s ̊a kallad ro ̈relsesimu- leringsplatform. En s ̊adan platform, d ̈opt till BIRGIT, har byggts vid Institutionen f ̈or kliniska neurovetenskaper vid Karolinska Institutet. Denna har ej bo ̈rjat anva ̈ndas ̈annu d ̊a dess prestanda fo ̈rst beho ̈ver utv ̈arderas. Syftet med denna uppsats ̈ar att utva ̈rdera precision och noggrannhet hos BIRGIT. Dessutom, att utv ̈ardera hur kroppsvikt och ro ̈relseriktning inverkar p ̊a prestandan. I arbetet ing ̊ar ̈aven att testa om det a ̈r m ̈ojligt att stabilisera huvudet under accelerationsfasen. Repeterade ma ̈tningar av sann acceleration med olika last, riktning, bo ̈rac- celeration och r ̈orelsetyp (rotation eller sidledes) genomfo ̈rdes. Testdockor anva ̈ndes fo ̈r att simulera lasten i prestandatesterna och riktiga testpersoner anva ̈ndes i huvudstabiliseringsdelen. Variansanalys (ANOVA) var det hu- vudsakliga statistiska verktyget. Resultatet antyder att last och ro ̈relseriktning inverkar p ̊a acceleratio- nen och prestandan och att den sanna accelerationen alltigenom a ̈r la ̈gre a ̈n bo ̈raccelerationen. Det finns tv ̊a sto ̈rre problem hos plattformen, det fo ̈rsta a ̈r att uppha ̈ngningen till stolen lutar och detta resulterar i en skillnad mellan riktningarna (det g ̊ar fortare nedf ̈ors). Det andra problemet a ̈r ett cykliskt uppfo ̈rande na ̈r flera rotationsr ̈orelser skall fo ̈lja p ̊a varandra. Stabiliseringsstudien visade att det g ̊ar att stabilisera huvudet.
14

Prozesssprachenbasiertes System zur Ansteuerung digitaler Menschmodelle als Teilkomponente einer Software zur Planung und Visualisierung menschlicher Arbeit in der Digitalen Fabrik / Process language based system for controlling digital human models as a software component for planning and visualization of human activities in the Digital Factory

Bauer, Sebastian 08 March 2016 (has links) (PDF)
Die Werkzeuge und Methoden der Digitalen Fabrik sind bereits seit vielen Jahren in den einzelnen Phasen des Produktentstehungsprozess im Einsatz. Sie werden dabei u.a. auch zur Planung und Gestaltung menschlicher Arbeit eingesetzt. Mit Hilfe digitaler Menschmodelle können Aspekte des Arbeitsablaufs, der Zeitwirtschaft und der Arbeitsplatzgestaltung bereits frühzeitig untersucht und verbessert werden. Die Entwicklung effizienter Simulationssysteme steht auf diesem Gebiet jedoch insbesondere im Vergleich mit anderen Bereichen, wie beispielsweise der Robotersimulation, noch am Anfang. Die vorliegende Arbeit beschäftigt sich zunächst mit der Analyse bereits existierender Menschmodell-Simulationssysteme. Aus den identifizierten Schwachstellen dieser Systeme und weiteren durch Experteninterviews sowie Literaturrecherche gewonnenen Erkenntnissen wird eine Anforderungsliste erstellt, die als Grundlage für die Konzeption und Umsetzung eines innovativen Ansatzes zur Ansteuerung und Bewegungsgenerierung für digitale Menschmodelle dient. Diese neuartige Methodik wird schließlich in ein Simulations-Softwaresystem implementiert und anschließend im Praxis-Einsatz evaluiert. Es konnte gezeigt werden, dass das neue System die Mängel der vorhandenen Systeme behebt und somit als Werkzeug zur effizienten Planung, Gestaltung und Bewertung menschlicher Arbeit geeignet ist. / For many years the tools and methods of the Digital Factory are used in various stages of the product development process. They are also used for the planning and design of human work, which is typically done using a digital human model. Aspects of the workflow, time management and workplace design can be investigated and improved upon in the early stages of the product development process using digital human models. But in this field the development of efficient simulation systems is not matured enough compared to other fields for e.g. robot simulation. This paper starts with an analysis of existing simulation systems for digital human models. Afterwards a requirements list is created from the identified weaknesses of these systems, knowledge gained through expert interviews and literature reviews. These requirements serve as the base for the design and implementation of an innovative approach for motion generation and control of digital human models. This new methodology is then implemented as a simulation software system and evaluated in practical applications. The developed system fixed the shortcomings of existing systems and thus it is a suitable tool for efficient planning, design and evaluation of human labor.
15

Génération d'accélérogrammes synthétiques large-bande : contribution à l’estimation de l’aléa sismique par validation d’approches en aveugle / Generation of broadband synthetic accelerograms : contribution to seismic hazard assessment by validation of blind approaches

Honoré-Foundotos, Laëtitia 10 July 2013 (has links)
L’une des problématique scientifique majeure en sismologie est de pouvoir estimer les mouvements du sol attendus en un site pour un futur séisme. L’objectif de cette thèse est de tester et de valider deux méthodes de simulation des mouvements du sol basées sur l’approche des fonctions de Green empiriques et d’apporter des éléments pouvant aider au développement d’une méthodologie de simulation en aveugle. Dans une première partie, une méthode de simulation basée sur une approche stochastique en point-source est validée sur les données réelles de séismes récents bien instrumentés : le séisme des Saintes Mw6.4 et le séisme de L’Aquila Mw6.3. Nous avons développé une approche de simulation en aveugle en prenant en compte une incertitude sur le paramètre de rapport des chutes de contrainte C. Cette approche permet de générer un ensemble d’accélérogrammes synthétiques d’un séisme cible suffisamment variés pour être représentatifs d’un grand nombre de scénarios de sources possibles et prenant en compte dans un sens statistique de potentiels effets de directivité. Cette approche a également été appliquée à la simulation d’un séisme historique pyrénéen Mw6.1. Dans une seconde partie, nous nous appuyons sur un modèle de source étendue plus complexe, combinant des modèles cinématiques de sources composites fractales avec l’approche des FGEs. Le potentiel de la méthode est testé sur une application au séisme de L’Aquila. Cela a permis de produire des résultats très satisfaisants sur l’ensemble des paramètres des mouvements du sol analysés. Cette méthode de simulation apparaît comme étant très prometteuse pour la mise en œuvre d’une méthodologie de simulation en aveugle, même si la principale difficulté réside dans la nécessité de définir la variabilité de nombreux paramètres d’entrée mal connus dans le cadre de la simulation d’un futur séisme. / One of the major scientific problems in seismology is to estimate the ground motions expected at a given site from a future earthquake. The aim of this thesis is to test and validate two different methods of ground motions simulation based on the empirical Green’s function approach and to provide elements that can help to develop a blind simulation methodology. In a first part, a simulation method based on a stochastic point source approach is validated on the real data of recent earthquakes well instrumented : the Les Saintes earthquake Mw6.4 and the L’Aquila earthquake Mw6.3. We have developed a blind simulation approach by taking into account an uncertainty on the parameter of stress drop ratio C. This approach allows to generate a set of synthetic accelerograms of a target earthquake varied enough to be representative of a large number of possible source scenario and taking into account in a statistical sense potential directivity effects. This approach is also applied to the simulation of an historical Pyrenean earthquake Mw6.1. In a second part, we use a more complex extended source model, combining kinematic models of fractal composite sources with EGF approach. The potential of the method is tested on an application to L’Aquila earthquake. This has produced very satisfying results on all ground motion parameters analyzed. This simulation method appears to be very promising for the implementation of a blind simulation methodology, even if the main difficulty lies in the need to define the variability of many poorly known input parameters in the simulation of a future earthquake.
16

以演化方式模擬人群運動行為 / Simulating Crowd Motion with Evolutionary Computation

王智賢, Wang, Chih-Chien Unknown Date (has links)
近年來,在電腦動畫的應用中,虛擬人群模擬的需求越來越多;但人群運動的模擬對於動畫設計師而言,仍是一件十分繁瑣耗時的工作。過去有許多研究曾以虛擬力場模擬簡單的生物群聚行為,但所模擬出的動畫品質與虛擬力場的參數及虛擬環境息息相關,因此經常需要以人工的方式耗時地調整出適當的虛擬力場參數。因此,我們提議以此問題定義成一個基因演算法的問題,針對不同的移動行為,定義適切的適應函數,再由系統根據不同環境自動演化出適當的虛擬力權重組合,以供產生不同人群移動行為之動畫時參考。在本篇論文中,我們已完成基因演算法的設計及人群動畫模擬系統,並設計了不同的典型環境進行電腦模擬實驗,以驗證此方法的可行性。 / The demands for virtual crowd simulation have been increasing in recent years but creating realistic crowd motions remains a complex and time-consuming task for a computer animator. In the literature、much work has been proposed to use virtual forces to simulate the motion of a group of virtual creatures such as birds and fishes. However、the quality of the simulations largely depends on the weights of the component virtual forces as well as the scene where the agents are situated. Usually it requires the animator to tune these parameters for a specific scene in order to obtain the desired result. In this thesis、we propose to use genetic algorithm to generate an optimal set of weighting parameters for composing virtual forces according to the given environment and desired movement behavior. We have implemented the proposed genetic algorithm as well as the crowd simulation system. Extensive experiments have also been conducted to study the effects of typical scenes and behaviors on the parameter sets and verify the feasibility of the approach.
17

Simulationsbasierte Absicherung der Ergonomie mit Hilfe digital beschriebener menschlicher Bewegungen

Schönherr, Ricardo 10 February 2014 (has links) (PDF)
Digitale Menschmodelle gelten als gut geeignete Werkzeuge zur Planung und Bewertung manueller Arbeit, insbesondere zur präventiven Ergonomieabsicherung. Bislang ist jedoch der Funktionsumfang der Softwaretools unzureichend und der Bedienaufwand zu hoch. In der vorliegenden Arbeit wird daher die Entwicklung einer Methode zur Aufbereitung digital erfasster menschlicher Bewegungen für die Bewegungsgenerierung und semiautomatische Ergonomiebewertung beschrieben. Nach einer Diskussion des gegenwärtigen Wissensstandes folgt die Darstellung zweier empirischer Untersuchungen zur Bewegungserfassung und -auswertung. Anschließend wird die Implementierung eines mehrere Belastungsfaktoren umfassenden Kombinationsverfahrens zur Ergonomiebewertung erläutert. Die gewonnenen Erkenntnisse zur Bewegungsgenerierung und Ergonomiebewertung fließen in die Entwicklung einer Software zur Planung und Bewertung manueller Arbeit, den Editor menschlicher Arbeit (ema), ein. Schließlich erfolgt eine Evaluation anhand realer Planungsszenarien. / Digital Human Models are said to be appropriate tools for planning and assessing human work; especially for preventive ergonomics risk assessment. Up to now, the functional range of established software tools is not sufficient and the operation is too complex and time consuming. Thus, in the present doctoral thesis, the development of a method for the preparation of digitally captured human motions for an algorithmic motion generation and automatic ergonomic risk assessment is described. On the summarization of the relevant current level of knowledge follows the description of two empirical studies for motion capturing and analysis. Afterwards the implementation of a method of the ergonomics risk assessment that combines several biomechanical risk factors is explained. The results of the preliminary studies flow into the development of a new software tool for planning and assessing human work – the editor for manual work activities (ema). Finally, the practical evaluation with the help of real planning scenarios is presented.
18

Prozesssprachenbasiertes System zur Ansteuerung digitaler Menschmodelle als Teilkomponente einer Software zur Planung und Visualisierung menschlicher Arbeit in der Digitalen Fabrik

Bauer, Sebastian 08 March 2016 (has links)
Die Werkzeuge und Methoden der Digitalen Fabrik sind bereits seit vielen Jahren in den einzelnen Phasen des Produktentstehungsprozess im Einsatz. Sie werden dabei u.a. auch zur Planung und Gestaltung menschlicher Arbeit eingesetzt. Mit Hilfe digitaler Menschmodelle können Aspekte des Arbeitsablaufs, der Zeitwirtschaft und der Arbeitsplatzgestaltung bereits frühzeitig untersucht und verbessert werden. Die Entwicklung effizienter Simulationssysteme steht auf diesem Gebiet jedoch insbesondere im Vergleich mit anderen Bereichen, wie beispielsweise der Robotersimulation, noch am Anfang. Die vorliegende Arbeit beschäftigt sich zunächst mit der Analyse bereits existierender Menschmodell-Simulationssysteme. Aus den identifizierten Schwachstellen dieser Systeme und weiteren durch Experteninterviews sowie Literaturrecherche gewonnenen Erkenntnissen wird eine Anforderungsliste erstellt, die als Grundlage für die Konzeption und Umsetzung eines innovativen Ansatzes zur Ansteuerung und Bewegungsgenerierung für digitale Menschmodelle dient. Diese neuartige Methodik wird schließlich in ein Simulations-Softwaresystem implementiert und anschließend im Praxis-Einsatz evaluiert. Es konnte gezeigt werden, dass das neue System die Mängel der vorhandenen Systeme behebt und somit als Werkzeug zur effizienten Planung, Gestaltung und Bewertung menschlicher Arbeit geeignet ist. / For many years the tools and methods of the Digital Factory are used in various stages of the product development process. They are also used for the planning and design of human work, which is typically done using a digital human model. Aspects of the workflow, time management and workplace design can be investigated and improved upon in the early stages of the product development process using digital human models. But in this field the development of efficient simulation systems is not matured enough compared to other fields for e.g. robot simulation. This paper starts with an analysis of existing simulation systems for digital human models. Afterwards a requirements list is created from the identified weaknesses of these systems, knowledge gained through expert interviews and literature reviews. These requirements serve as the base for the design and implementation of an innovative approach for motion generation and control of digital human models. This new methodology is then implemented as a simulation software system and evaluated in practical applications. The developed system fixed the shortcomings of existing systems and thus it is a suitable tool for efficient planning, design and evaluation of human labor.
19

Simulationsbasierte Absicherung der Ergonomie mit Hilfe digital beschriebener menschlicher Bewegungen

Schönherr, Ricardo 30 January 2014 (has links)
Digitale Menschmodelle gelten als gut geeignete Werkzeuge zur Planung und Bewertung manueller Arbeit, insbesondere zur präventiven Ergonomieabsicherung. Bislang ist jedoch der Funktionsumfang der Softwaretools unzureichend und der Bedienaufwand zu hoch. In der vorliegenden Arbeit wird daher die Entwicklung einer Methode zur Aufbereitung digital erfasster menschlicher Bewegungen für die Bewegungsgenerierung und semiautomatische Ergonomiebewertung beschrieben. Nach einer Diskussion des gegenwärtigen Wissensstandes folgt die Darstellung zweier empirischer Untersuchungen zur Bewegungserfassung und -auswertung. Anschließend wird die Implementierung eines mehrere Belastungsfaktoren umfassenden Kombinationsverfahrens zur Ergonomiebewertung erläutert. Die gewonnenen Erkenntnisse zur Bewegungsgenerierung und Ergonomiebewertung fließen in die Entwicklung einer Software zur Planung und Bewertung manueller Arbeit, den Editor menschlicher Arbeit (ema), ein. Schließlich erfolgt eine Evaluation anhand realer Planungsszenarien. / Digital Human Models are said to be appropriate tools for planning and assessing human work; especially for preventive ergonomics risk assessment. Up to now, the functional range of established software tools is not sufficient and the operation is too complex and time consuming. Thus, in the present doctoral thesis, the development of a method for the preparation of digitally captured human motions for an algorithmic motion generation and automatic ergonomic risk assessment is described. On the summarization of the relevant current level of knowledge follows the description of two empirical studies for motion capturing and analysis. Afterwards the implementation of a method of the ergonomics risk assessment that combines several biomechanical risk factors is explained. The results of the preliminary studies flow into the development of a new software tool for planning and assessing human work – the editor for manual work activities (ema). Finally, the practical evaluation with the help of real planning scenarios is presented.

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