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Kvalsvik, Jakobsen Andreas. "Tessellation based Terrain Rendering." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for datateknikk og informasjonsvitenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18623.
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Modern Graphics Processing Units (GPU) exhibit a high degree of parallelism and over the years have grown to adopt an increasing number of techniques to speed-up photorealistic rendering. One such technique is tessellation, i.e. the recursive subdivision of object elements into finer or coarser parts with the aim of achieving the appropriate amount of detail. The aim of this thesis is an adaptive tessellation algorithm for terrain rendering which can highlight important parts of the terrain while maintaining reasonable performance. This algorithm needs to be crack-free to avoid pixel faults between adjacent patches. A prototype was created in OSG, with GLSL shaders. The adaptive tessellation used three tessellation selection factors based on distance, a tessellation map and normals. An OSG program with five GLSL shaders (vertex, tessellation control, tessellation evaluation, geometry and fragment) was created for the tessellation of the terrain. The greatest advantage of tessellation is the reduced bandwidth between memory and GPU. Tessellation improves FPS, because it's faster to control vertices on the GPU than on the CPU.
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Hess, Steffen. "Particle hydrodynamics with tessellation techniques." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-131613.
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Cervin, Albert. "Adaptive Hardware-accelerated Terrain Tessellation." Thesis, Linköpings universitet, Medie- och Informationsteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-91334.
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In this master thesis report, a scheme for adaptive hardware terrain tessellation is presented. The scheme uses an offline processing approach where a height map is analyzed in terms of curvature and the result is stored in a resource called density map. This density map is then bound as a resource to the hardware tessellation stage and used to bias the tessellation factor for a given edge. The scheme is implemented inside FrostbiteTM2 by EATM DICETM and produces good results while making the heightfield rendering more efficient. The performance gain can be used to increase the rendering detail, allowing for better visual appearance for the terrain mesh. The scheme is currently implemented for hardware tessellation but could also be used for software terrain mesh generation. The implementation works satisfactory and produces good results with a reasonable speed.I den här rapporten för examensarbete presenteras en algoritm för att utföra adaptiv hårdvarutessellation av terräng. Algoritmen använder sig av ett offline-steg där ett höjdfält analyseras med avseende på kurvatur och resultatet lagras i en densitets-karta. Den här densitets-kartan används sedan som en resurs i hårdvarutessellationen där den påverkar en tessellationsfaktor för en given triangel-kant. Algoritmen har implementerats i spelmotorn FrostbiteTM2 skapad av EATM DICETM och producerar goda resultat samtidigt som den gör rendering av terrängen effektivare. Detta medf¨or att detaljnivån för terrängrenderingen kanökas, vilket i sin tur leder till en visuell förbättring. Algoritmen är för närvarande endast implementerad för hårdvarutessellation men skulle också kunna användas för mjukvarugenerering av terrängens geometri. Algoritmen fungerar tillfredsställande och producerar goda resultat med en acceptabel hastighet.
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Panzitta, Michael James. "Tessellation for computer image generation." Master's thesis, University of Central Florida, 1987. http://digital.library.ucf.edu/cdm/ref/collection/RTD/id/2611.
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University of Central Florida College of Engineering ThesisOf the vast number of algorithms used in modern computer image generation, most rely upon data bases comprised of polygons. This becomes a severe impediment when curved objects must be modeled and displayed with an acceptable level of speed and accuracy. A technique is needed to provide a means of modeling curved surfaces, storing them in a data base, and displaying them using existing algorithms. Tessellation is one methd of achieving such goals.
M.S.
Masters;
College of Engineering
Engineering
Engineering
51 p.
vi, 51 leaves, bound : ill. ; 28 cm.
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O'Connor, Kevin Luke. "Image segmentation through optimal tessellation." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47210.
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Schaap, Willem Egbert. "DTFE the Delaunay Tessellation Field Estimator /." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2006. http://irs.ub.rug.nl/ppn/298831376.
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Löwgren, Martin, and Niklas Olin. "PN-triangle tessellation using Geometry shaders : The effect on rendering speed compared to the fixed function tessellator." Thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-3818.
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With each computer game generation there is always a demand for more visually pleasing environments. This pushes game developers to create more powerful rendering techniques and game artists to create more detailed art. With a visually stunning backdrop also comes the need for high-resolution models. A common issue is that if all models in a scene are high-resolution it would not only require immensely powerful hardware, it would also be wasteful as only the models in the foreground are close enough that we would recognize the increased details. The common solution to this problem has been to load several versions of each model containing varying amounts of detail. However this solution has the drawback that it increases our memory footprints as more models are loaded into the memory. Tessellation offers a more dynamic solution to the problem as it only requires us to load a low-resolution model and higher resolution versions can be generated during run-time on the GPU. With the introduction of DirectX 11 tessellation is now supported in the hardware, however we are still a few years away from seeing DirectX 11 being used as the core of any 3D rendering engine. In a transitional period like this between hardware generations game developers has to tackle the dilemma that the current hardware generation has to be supported when creating games that will also utilize the next generation. This thesis focuses on comparing the performance of a tessellation scheme supported by the current hardware generation, DirectX 10, as opposed to a scheme developed for the next generation, DirectX 11. Two prototypes, one using the Geometry shader that was introduced in DirectX 10 and the other using the fixed function tessellator introduced in DirectX 11, were built to compare the performance of tessellated model rendering. Several different variants of each prototype were tested and the general conclusion is that the tessellator performed better than the Geometry shader.
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Lambert, Thibaud. "Level-Of-Details Rendering with Hardware Tessellation." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0948/document.
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Au cours des deux dernières décennies, les applications temps réel ont montré des améliorations colossales dans la génération de rendus photoréalistes. Cela est principalement dû à la disponibilité de modèles 3D avec une quantité croissante de détails. L'approche traditionnelle pour représenter et visualiser des objets 3D hautement détaillés est de les décomposer en un maillage basse fréquence et une carte de déplacement encodant les détails. La tessellation matérielle est le support idéal pour implémenter un rendu efficace de cette représentation. Dans ce contexte, nous proposons une méthode générale pour la génération et le rendu de maillages multi-résolutions compatibles avec la tessellation matérielle. Tout d'abord, nous introduisons une métrique dépendant de la vue capturant à la fois les distorsions géométriques et paramétriques, permettant de sélectionner la le niveau de résolution approprié au moment du rendu. Deuxièmement, nous présentons une nouvelle représentation hiérarchique permettant d'une part des transitions temporelles et spatiales continues entre les niveaux et d'autre part une tessellation matérielle non uniforme. Enfin, nous élaborons un processus de simplification pour générer notre représentation hiérarchique tout en minimisant notre métrique d'erreur. Notre méthode conduit à d'énormes améliorations tant en termes du nombre de triangles affiché qu'en temps de rendu par rapport aux méthodes alternativesIn the last two decades, real-time applications have exhibited colossal improvements in the generation of photo-realistic images. This is mainly due to the availability of 3D models with an increasing amount of details. Currently, the traditional approach to represent and visualize highly detailed 3D objects is to decompose them into a low-frequency mesh and a displacement map encoding the details. The hardware tessellation is the ideal support to implement an efficient rendering of this representation. In this context, we propose a general framework for the generation and the rendering of multi-resolution feature-aware meshes compatible with hardware tessellation. First, we introduce a view-dependent metric capturing both geometric and parametric distortions, allowing to select the appropriate resolution at rendertime. Second, we present a novel hierarchical representation enabling on the one hand smooth temporal and spatial transitions between levels and on the other hand a non-uniform hardware tessellation. Last, we devise a simplification process to generate our hierarchical representation while minimizing our error metric. Our framework leads to huge improvements both in terms of triangle count and rendering time in comparison to alternative methods
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Alonso, Ortega Rodrigo Ignacio. "A delaunay Tessellation based void finder algorithm." Tesis, Universidad de Chile, 2016. http://repositorio.uchile.cl/handle/2250/139868.
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Magíster en Ciencias, Mención ComputaciónIngeniero Civil en Computación
En el campo de la cosmología, los vacíos son regiones del espacio cuya densidad es nota- blemente menor que la densidad de fondo, abarcando distancias en el rango de 20 50 Mpc/h (1 Mpc/h ∼ 2,10 × 1019 km). Los primeros vacíos fueron descubiertos en los primeros catá- logos sistemáticos de galaxias lejanas a fines de la década de 1970. Sus propiedades han sido reconocidas como críticas para la comprensión de la estructura a gran escala del universo. Múltiples esfuerzos han sido destinados al estudio de los vacíos cósmicos para una mejor com- prensión de las etapas tempranas y posterior evolución del universo a gran escala, mediante el refinamiento y validación de los modelos cósmicos actuales. La tarea de detectar vacíos, sin embargo, no es trivial y es subjetiva pues la definición de vacío es algo ambigua. Hasta el día de hoy diversos autores continúan investigando este campo, por ejemplo mediante el diseño de mejores algoritmos para detectarlos dentro de catálogos o surveys de galaxias. Considerando lo anterior, hemos desarrollado un algoritmo de detección de vacíos basado en teselaciones de Delaunay: el algoritmo DELFIN (DELaunay Edge Void FINder) que se caracteriza por ser robusto, eficiente y extensible (tanto en 2-d y 3-d), aplicable en grandes catálogos de galaxias. Hemos alcanzado estas características mediante modificaciones y ex- tensiones sobre el algoritmo de Hervías et al. publicado en 2014. Nuestro algoritmo comparte algunas similitudes elementales con otros trabajos, pero las teselaciones de Delaunay proveen mayor maleabilidad y mejor rendimiento. Además, hemos validado nuestro algoritmo tanto con datos artificiales como reales, evaluándonos frente a un algoritmo buscador de vacíos ya existente (Foster y Nelson, 2008), con resultados alentadores. Tanto la implementación 2-d como la implementación 3-d (bajo ciertos supuestos) corren en tiempo O(n log n), donde n es el número de galaxias. Finalmente, proponemos algunas áreas para futura investigación, a partir de las cuales este algoritmo se vería beneficiado, así como también algunas sugerencias sobre cómo abordar y resolver algunos problemas asociados.
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Olsson, Victor, and Viktor Eklund. "CPU Performance Evaluation for 2D Voronoi Tessellation." Thesis, Blekinge Tekniska Högskola, Institutionen för datavetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-18259.
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Voronoi tessellation can be used within a couple of different fields. Some of these fields include healthcare, construction and urban planning. Since Voronoi tessellations are used in multiple fields, it is motivated to know the strengths and weaknesses of the algorithms used to generate them, in terms of their efficiency. The objectives of this thesis are to compare two CPU algorithm implementations for Voronoi tessellation in regards to execution time and see which of the two is the most efficient. The algorithms compared are The Bowyer-Watson algorithm and Fortunes algorithm. The Fortunes algorithm used in the research is based upon a pre-existing Fortunes implementation while the Bowyer-Watson implementation was specifically made for this research. Their differences in efficiency were determined by measuring their execution times and comparing them. This was done in an iterative manner, where for each iteration, the amount of data to be computed was continuously increased. The results show that Fortunes algorithm is more efficient on the CPU without using any acceleration techniques for any of the algorithms. It took 70 milliseconds for the Bowyer-Watson method to calculate 3000 input points while Fortunes method took 12 milliseconds under the same conditions. As a conclusion, Fortunes algorithm was more efficient due to the Bowyer-Watson algorithm doing unnecessary calculations. These calculations include checking all the triangles for every new point added. A suggestion for improving the speed of this algorithm would be to use a nearest neighbour search technique when searching through triangles.
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Ye, Ziqiao. "Tessellation of the sphere with different compression techniques." Thesis, University of Gävle, Department of Industrial Development, IT and Land Management, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-7373.
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Many kinds of data have a spherical representation, the idea is to tessellate the "sphere" in an efficient way and then decode the data so it can be compressed easily. In this paper, the process of exploration will start from the basic spherical wavelet-like to some new tessellation compression techniques in 3D to decompose the sphere with squares or triangles. The produced tessellation will have more round corners and the artefacts will be less prominent. Earth map will be textured on the sphere to compare the effect of different compression techniques.
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Jamali, Firouzabadi Farshad. "Magic carpet : digital interpretation of traditional tessellation patterns." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/4163.
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Contemporary architecture has failed to engage the rich culture of planar and spatial
transformations of historical Muslim architecture, often relegating it to a form of naive pastiche
or, at best, to the realm of historical reconstruction. In this project we make use of current digital
technologies in an attempt to revisit and reinterpret, in modern terms, the geometric structure of
patterns embedded in the historic Islamic architecture of Iran. The original contribution of this
project lies in extending traditional two dimensional tiling patterns into a dynamic three
dimensional state with the help of computational tools. The analogy to the classical Persian
carpet as well as mobile character of design can also be seen as original. The notion of
‘transparency’ and ‘dynamism’ are interpreted using Autodesk’s Maya and Bentley’s Generative
Components software. This report illustrates initial explorations and outlines future possibilities.
In the past architects of the country were responsible for making the enclosure heaven-like
while it was carpet weavers’ job to make the floor heaven-like. In this project as a symbolic
approach, carpet and weaving becomes both the enclosure and the floor to define both floor
and roof and symbolize the new approach through which we as architects use other disciplines
and new tools such as new software to learn and shape the space and discover new vocabulary
for a contemporary and local architecture for Iran.
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Nießner, Matthias [Verfasser]. "Rendering Subdivision Surfaces using Hardware Tessellation / Matthias Nießner." München : Verlag Dr. Hut, 2013. http://d-nb.info/1042878218/34.
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A-iyeh, Enoch. "Voronoi tessellation quality: applications in digital image analysis." A-iyeh E., Peters, J.F, Proximal Groupoid Patterns in Digital Images, Computing Research Repository: Computer Vision and Pattern Recognition, 2016, 2017. http://hdl.handle.net/1993/32055.
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A measure of the quality of Voronoi tessellations resulting from various mesh
generators founded on feature-driven models is introduced in this work. A planar
tessellation covers an image with polygons of various shapes and sizes. Tessellations
have potential utility due to their geometry and the opportunity to derive useful
information from them for object recognition, image processing and classification.
Problem domains including images are generally feature-endowed, non-random
domains. Generators modeled otherwise may easily guarantee quality of meshes
but certainly bear no reference to features of the meshed problem domain. They
are therefore unsuitable in point pattern identification, characterization and subsequently
the study of meshed regions. We therefore found generators on features of the problem domain. This provides a basis for element quality studies and improvement based on quality criteria. The resulting polygonal meshes tessellating an n-dimensional digital image into convex regions are of varying element qualities.
Given several types of mesh generating sets, a measure of overall solution quality is
introduced to determine their effectiveness. Given a tessellation of general and mixed
shapes, this presents a challenge in quality improvement. The Centroidal Voronoi
Tessellation (CVT) technique is developed for quality improvement and guarantees
of mixed, general-shaped elements and to preserve the validity of the tessellations.
Mesh quality indicators and entropies introduced are useful for pattern studies, analysis,
recognition and assessing information. Computed features of tessellated spaces are explored for image information content assessment and cell processing to expose
detail using information theoretic methods. Tessellated spaces also furnish information
on pattern structure and organization through their quality distributions.
Mathematical and theoretical results obtained from these spaces help in understanding
Voronoi diagrams as well as for their successful applications. Voronoi diagrams
expose neighbourhood relations between pattern units. Given this realization, the
foundation of near sets is developed for further applications.February 2017
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Cerrone, Kathryn L. "TESSELLATIONS: LESSONS FOR EVERY AGE." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1151427935.
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Olaranont, Nonthakorn. "2-D Epithelial Tissues, Cell Mechanics, and Voronoi Tessellation." Digital WPI, 2019. https://digitalcommons.wpi.edu/etd-theses/1308.
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In this thesis, we develop a new computational method using Voronoi vertex model and energy to describe the cell-cell interaction among the epithelial tissue. Several studies and simulations will be showed such as equilibrium states, wound closure process, and abnormal growth. We also perform analysis on circular epithelial wound closure process.
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Heß, Steffen [Verfasser], and Simon [Akademischer Betreuer] White. "Particle hydrodynamics with tessellation techniques / Steffen Heß. Betreuer: Simon White." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2011. http://d-nb.info/1015083730/34.
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Lee, Sunmi. "The edge-isoperimetric problem for the square tessellation of plane." CSUSB ScholarWorks, 2000. https://scholarworks.lib.csusb.edu/etd-project/1622.
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The solution for the edge-isoperimetric problem (EIP) of the square tessellation of plane is investigated and solved. Summaries of the stabilization theory and previous research dealing with the EIP are stated. These techniques enable us to solve the EIP of the cubical tessellation.
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Ravindran, Adithya. "Implementation of handwritten text recognition using density value of Delauney tessellation." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-333871.
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This paper presents a novel Word spotting technique for handwritten documentsusing density value of Delaunay triangulation. Delaunay tessellation is constructedfrom a set of data points on a query image and the density value is computed for eachdata point. This information is either directly used for training in a feed-forward neural network or used to compute the probability estimates of a class from Delaunay Tessellation Field Estimation and classification follows using naive Bayesian classifier. This paper discusses the performance of a Delaunay tessellation fieldestimation model and neural network model.
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川平, 友規, and TOMOKI kAWAHIRA. "Tessellation and Lyubich–Minsky laminations associated with quadratic maps, I: pinching semiconjugacies." Cambridge University Press, 2009. http://hdl.handle.net/2237/14319.
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Nystad, Jørgen. "Parametric Generation of Polygonal Tree Models for Rendering on Tessellation-Enabled Hardware." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for datateknikk og informasjonsvitenskap, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-12211.
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The main contribution of this thesis is a parametric method for generation of single-mesh polygonal tree models that follow natural rules as indicated by da Vinci in his notebooks. Following these rules allow for a relatively simple scheme of connecting branches to parent branches. Proper branch connection is a requirement for gaining the benefits of subdivision. Techniques for proper texture coordinate generation and subdivision are also explored.The result is a tree model generation scheme resulting in single polygonal meshes susceptible to various subdivision methods, with a Catmull-Clark approximation method as the evaluated example.As realistic visualization of tree models is the overall objective, foliage appearance and the impression of a dense branching structure is considered. A shader-based method for accurately faking high branch density at a distance is explored.
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Bernauer, Julie. "Utilisation de la tessellation de Voronoï pour l'étude des complexes protéine-protéine." Phd thesis, Université Paris Sud - Paris XI, 2006. http://tel.archives-ouvertes.fr/tel-00804990.
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La fonction d'une protéine est souvent subordonnée à l'interaction avec un certain nombre de partenaires. L'étude de la structure tridimensionnelle de ces complexes, qui ne peut souvent se faire expérimentalement, permettrait la compréhension de nombreux processus cellulaires. Le travail présenté ici se compose de deux parties. La première traite de la mise en place d'une fonction de score pour l'amarrage protéine-protéine et la deuxième de l'étude cristallographique d'une protéine tétramérique qui est une cible antibiotique potentielle : la thymidylate synthase X de Paramecium bursaria Chlorella virus. La modélisation des complexes protéine-protéine ou docking comporte deux étapes successives : d'abord, un grand nombre de conformations sont générées, puis une fonction de score est utilisée pour les classer. Cette fonction de score doit prendre en compte à la fois la complémentarité géométrique des deux molécules et les propriétés physico-chimiques des surfaces en interaction. Nous nous sommes intéressés à la seconde étape à travers le développement d'une fonction de score rapide et fiable. Ceci est possible grâce à la tessellation de Voronoï de la structure tridimensionnelle des protéines. En effet, les tessellations de Voronoï ou de Laguerre se sont avérées être de bons modèles mathématiques de la structure des protéines. En particulier, cette formalisation permet de faire une bonne description de l'empilement et des propriétés structurales des résidus. Cette modélisation rend compte l'empilement des résidus à l'interface entre deux protéines. Ainsi, il est possible de mesurer un ensemble de paramètres sur des complexes protéine-protéine dont la structure est connue expérimentalement et sur des complexes leurres générés artificiel- lement. Ces paramètres, sont la fréquence d'apparition des résidus ou des paires de résidus, les volumes des cellules de Voronoï, les distances entre les résidus en contact à l'interface, la surface de l'interface et le nombre de résidus à l'interface. Ils ont été utilisés en entrée de procédures d'apprentissage statistique. Grâce à ces procédures (apprentissage logistique, séparateurs à vaste marge (SVM) et algorithmes génétiques), on peut obtenir des fonctions de score efficaces, ca- pables de séparer les leurres des structures réelles. Dans un deuxième temps, j'ai déterminé expérimentalement la structure de la thymidylate synthase X, cible antibiotique de choix. La thymidylate synthase X est une flavoprotéine qui a été découverte récemment. Elle intervient dans la synthèse du dTMP chez la plupart des procaryotes mais n'existe pas chez les eucaryotes supérieurs. Cette protéine catalyse le transfert de methyle du tétrahydrofolate vers le dUMP grâce à son cofacteur le FAD et au NADPH qui intervient comme substrat. La structure tridimensionnelle de l'homotétramère de la thymidylate synthase X en présence de son cofacteur, le FAD, a été résolue à 2.4 Å par remplacement moléculaire. Comme pour les structures de thymidylate synthase X de Thermotoga maritima et de Mycobacterium tuberculosis précédemment résolues, le monomère se compose d'un coeur de feuillets β et de deux hélices α à son extrémité. Le site actif se trouve à l'interface de trois monomères, la partie isoalloxazine du FAD étant accessible au solvant et proche d'une longue boucle flexible. La fixation du FAD dans cette structure est légèrement différente de celles déjà observées par la conformation de la partie adénine. Cette structure, associée aux études de mutagénèse dirigée de nos collaborateurs, a permis de mettre évidence des résidus jouant un rôle majeur lors de la catalyse.
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Motukupalli, Ravindranath Swathi. "Life time improvement of Wireless Body Area Networks using Clustered Voronoi Tessellation." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1446547308.
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Gottheil, Jeremy. "Modelling Mineral Liberation of Ore Breakage to Improve the Overall Efficiency of Mining Operations." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42555.
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As the demand for a low-carbon and environmentally friendly future increases, so does the importance of mineral and metal commodities. The production of solar panels, wind turbines, energy storage systems and other green technologies require large quantities of minerals and rare earth metals. Natural Resources Canada noted that in 2019, Canada was a global leading producer in minerals required for green technology including graphite, nickel, cobalt, and others [1]. While mineral production continues to rise year over year, the ore grade, i.e., the concentration of a desired material, of multiple common minerals continues to decline.
To liberate valuable minerals from low ore grade deposits size reduction processes such as crushing and grinding are required; however, these processes account for over half of all energy consumption on the average mine. As mines are typically remote, fossil fuels are normally used as the main energy source, producing large amounts greenhouse gases, necessitating the need for more efficient size reduction processes. This could be accomplished by predicting how a particular orebody would break. With the surge in image sensing and computing technologies at mining sites many researchers are exploring ore texture and processability characteristics of the ore body. If distinct processability characteristics change based on ore textural feature from a 2D image, then general trends for optimal size reduction of orebodies of similar texture can developed.
This work builds on previous work by simulating ore breakage through the superimposition of a predetermined fragmentation pattern, called a mask, onto multiple ore textures. Synthetic, periodic black and white 2D ore textures were created to find a link between simple textural features such as different mineral grain shape, size, and orientation and processability characteristics. A Monte Carlo simulation was performed to generate a large quantity of realistic product particles using the Voronoi tessellations masking technique. To assess the processability of different textures, the percentage area distribution of valuable minerals of each ore texture was compared across the complete range of particle sizes. The valuable mineral percentage area distributions were analyzed for rate and shape of the distribution as particle size decreases, with noticeable differences between textures. The distributions were also parameterized using a two-beta mixture distribution model, expanding on the traditional one beta model developed by King [2,3,4]. These distributions can eventually help the mining industry make informed decisions on how much grinding and crushing will be required to liberate desired minerals from waste rock.
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Liljekvist, Pontus Holmertz, and Andreas Zsigmond. "Real-Time Tessellation A Region of Interest Based Technique Suited for Game Applications." Thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2081.
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While the games industry grows, the need for visually appealing graphics increase. This drives the demand for new hardware and the development of new techniques forward. With the latest generation of 3D graphic APIs the new rendering pipeline technique tessellation was announced. With each generation of games getting more advanced, the demand for highly detailed models increase. This leads to a higher workload for the GPU. The purpose of this thesis is to research the fi eld of tessellation and develop a prototype to optimize the tessellation pipeline. The prototype is designed to help reduce the number of generated triangles by dividing the mesh into regions, each region with its own tessellation factor. The prototype implementation supports both manual and automatic generation of these regions. A new fi le format was developed to support the region data. The implementation was split into three parts; one Python based Maya plug-in used for preparing the model for exporting, one exporter for Maya that generated the output fi le, and one viewer application capable of rendering the resulting mesh. The geometry output of the proposed technique was evaluated by comparing it to uniformly tessellated reference mesh geometry. Measurements show that the proposed technique is capable of reducing the face count with minor or maintained correlation to the reference geometry.Medans spelindustrin växer ökar behovet av visuellt tilltalande grafik. Detta driver utvecklingen av hårdvara och nya tekniker framåt. Med den senaste generationens 3D grafik API kom renderingssteget tesselering. Eftersom varje generation av spel blir mer avancerat ökar efterfrågan på detaljerade modeller. Detta leder till en högre arbetsbörda för GPUn. Syftet med denna avhandling är att undersöka tesselering och utveckla en prototyp för att optimera tesseleringspipelinen. Prototypen är utformad för att hjälpa till att minska antalet genererade trianglar genom att dela upp figuren i regioner, varje region med egen tesseleringsfaktor. Prototypen stödjer både manuell och automatisk generering av dessa regioner, ett nytt filformat utvecklades för att stödja dessa. Prototypen delades upp i tre delar, ett Python baserat Maya plug-in som används för att förbereda modellen för export, en Maya exportör som genererar filerna, och ett visningsprogram som kan rendera den färdiga figuren. Figuren från den föreslagna tekniken utvärderades genom att jämföra den med motsvarande figur med universal tesseleringsfaktor. Mätningar visar att den föreslagna tekniken klarar att reducera antalet trianglar med låg felmarginal.
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Johansson, Tobias. "Procedurally Generated Lightning Bolts Using Tessellation and Stream-Output : A GPU Based Approach." Thesis, Blekinge Tekniska Högskola, Institutionen för kreativa teknologier, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-13708.
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Bock, Martin [Verfasser]. "Beyond whole-cell motion : reactive interpenetrating flow and elliptic Voronoi tessellation / Martin Bock." Bonn : Universitäts- und Landesbibliothek Bonn, 2013. http://d-nb.info/1044974389/34.
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Li, Yuhao. "Multiclass Density Estimation Analysis in N-Dimensional Space featuring Delaunay Tessellation Field Estimation." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-301958.
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Multiclass density estimation is a method that can both estimate the density of a field and classify a given point to its targeted class. Delaunay Tessellation Field Estimation is a tessellation based multiclass density estimation technique that has recently been resurfaced and has been applied in the field of astronomy and computer science. In this paper Delaunay Tessellation Field Estimation is compared with other traditional density estimation techniques such as Kernel Density Estimation, k-Nearest Neighbour Density, Local Reachability Density and histogram to deliver a detailed performance analysis. One of the main conclusions is that Delaunay Tessellation Field Estimation scales in the number of data points but not the dimensions.
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Tillgren, Sebastian. "Generating 3D Avalanche Slabs with Voronoi Tessellation in Real-Time on the CPU." Thesis, Blekinge Tekniska Högskola, Institutionen för datavetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-20223.
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In computer graphics, when simulating fractured or cracked objects, most commonly physically based methods or hybrid solutions using physical and procedural methods are used to achieve the result. If only a static representation of a cracked surface, and not a simulation of an object cracking, is desired, these approaches of crack generation are not suitable. Non-physically based methods to generate the cracks or fractured objects has also been used where a fracture pattern is projected onto an object. In this thesis a novel method of generating 3D avalanche slabs directly from a 2D Voronoi pattern, in real-time, without using physically based methods or 3D procedural crack generation is presented. After the slabs are generated, they are placed on the surface of a terrain. To add a more realistic look, snow is added on the mountain around the avalanche slabs. Using this novel method of generating 3D avalanche slabs, separate 3D mesh objects are created directly from the Voronoi pattern, and no 3D model is needed initially to generate them from. The results show that this method can be used in real-time with limitations. With improvements suggested in this thesis, the presented method could be used to generate a large amount of slabs in a fairly large region, and software developers can benefit from using this method in their graphics renderer.
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Khalili, Pegah. "Developing a triangular tessellation method for the analysis of medium ring pucker conformations." Master's thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/6636.
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The main focus of this thesis is to investigate the relative conformational flexibilities of α-, β- and γ-cyclodextrins in water by analysing their macrocyclic ring puckering motion from Molecular Dynamics (MD) simulations. In particular, the puckering of the CDs is investigated through a coarse grained analysis of full atomistic simulations, where the CD conformational motions are studied on the macrocyclic scale rather than the atomistic scale. The flexibilities of the cyclodextrins (CDs) are then compared to their experimentally-observed aqueous solubility trend in order to try explain the anomalously flow solubility of β-cyclodextrin. β-CD has important applications in industry, such as the pharmaceutical industry, thus exploring the conformational reasons for its low solubility can help to design more effective cyclodextrin-based products in future. The ring puckering of the CDs is measured quantitatively using a reduced system of puckering coordinates based on the method of triangular tessellation. The triangular tessellation definition for monocylic 6-membered rings is first extended to 7- and 8-membered rings, and the corresponding puckering coordinates are derived mathematically. The macrocyclic CD rings are then simplified to monocyclic representations through an appropriate coarse graining of the molecules (specifically, α-, β- and γ-cyclodextrins are simplified to 6-, 7- and 8-sided rings, respectively), and the corresponding triangular tessellation definition is then used to measure their macrocyclic puckering. The rates of decay of the puckering motion are then calculated using time correlation functions, from which the relative flexibilities of the CDs is determined. Probability distributions are also used to investigate the ranges of the CD puckering. In addition, the horizontal contraction and expansion of the macrocyclic rings (termed """"breathing"""" herein) is analysed to supplement the puckering analysis. Puckering coordinates based on the triangular tessellation of 6-membered rings have been used previously to characterise all 38 canonical states of cyclohexane. In this thesis, a systematic procedure is developed to generate the triangular tessellation puckering coordinates of all the canonical states of 6-, 7- and 8-membered rings, and the coordinates for all canonical states of cycloheptane and cyclooctane are subsequently generated. These puckering coordinates can be useful not only in the conformational analysis of cyclohexane, cycloheptane and cyclooctane, but also to quantitatively characterise the conformations of 6-, 7- and 8-membered rings in general, both from experimental and computational studies.
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Fleischer, Frank. "Analysis and fitting of random tessellation models applications in telecommunication and cell biology." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-59419.
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Kumaresan, Karthik. "Ultra-High Performance Concrete and Lattice Models." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/35144.
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Ultra-High Performance Concrete (UHPC) is an evolving structural material that has attracted interest in the civil engineering industry recently. Currently, it is being used mainly for highway infrastructure in the US and also being explored for various other applications. The existing design guides on UHPC in countries like Japan, Australia and France are not as detailed as the concrete or steel guides. Most of the sections made of UHPC are slender due to its superior mechanical properties which are expected to simplify construction. Being an expensive material to use, making slender sections also helps to minimize the overall cost of the structure and makes it competitive with that of high strength steel and prestressed concrete. It has also been demonstrated to have very high compressive strength and considerable tensile strength.
To begin with, an introduction on UHPC and its current applications around the world is presented, followed by a review of the existing design guides on UHPC. The importance as well as the methodology to measure fracture energy of concrete with factors to be considered for fiber reinforced concrete is discussed in detail. The main motive of this research is to introduce a creative modeling concept which served as the theoretical basis for the development of a computer program called Lattice 3D. The program is a modeling tool for engineers studying the behavior of UHPC, and in the future will be developed into a finite element protocol for analyzing complex structures made of UHPC. Parametric studies on lattice models of thin simply supported plates in compression and three-point bending of beams have been demonstrated in this research. Experimental tests conducted on briquette specimens under uniaxial tension are also discussed.Master of Science
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Johansson, Emil. "Analyzing performance for lighting of tessellated grass using LOD." Thesis, Blekinge Tekniska Högskola, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-22018.
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BackgroundThere are different methods for rendering grass in real-time, for video games. This thesis looks at an algorithm that uses hardware tessellation to generate geometry during run time. These concepts are explained in more detail in the introduction chapter as well as the method chapter. The objectives problem that this thesis revolves around is this; When rendering grass using tessellation a lot of geometry is created. This means that the grass might be a bottleneck, meaning it eats too much performance. This applies especially when adding lighting to a scene dense with grass. Lighting requires a lot more computations, so adding this can create a difference, a "dip" in performance. To try and aid this dip, LOD in different forms will be added. Then tests will be carried out to see if the divide is lessened. This would allow for a lot of lighting to be used together with this expensive technique. LOD means a way to lessen the geometry being rendered through different algorithms so that the performance cost will not be as high. methods answer the relevant research questions, a literature review was carried out. This is to understand the relevant 3D techniques better. And also to learn more about rendering grass through tessellation. Then an implementation was conducted, with this experiment to test different LOD techniques with and without lighting. Each scenario was tested ten times and the average framerate was measured and put into charts.ResultsThe average framerate dropped when light sources were added in all of the tests. The binary tree consumed more RAM usage but aided the framerate more than the quadtree. The VRAM usage for the grass tessellation was around 100 MB.ConclusionsFor future work, it would be interesting to compare different ways of rendering grass for the sake of user value. Do people prefer tessellated grass when minimal lighting is applied? Or do people prefer quads to represent grass? The results did not showthat the LOD implemented solved the issue presented in this thesis.
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Hins-Mallet, Karine. "Amélioration du processus de géosimulation des phénomènes urbains complexes par l'adaptation d'une tessellation Voronoï." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27046/27046.pdf.
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L’essor fulgurant des systèmes d’information géographiques et des bases de données spatiales a provoqué un phénomène similaire dans le domaine de la géosimulation urbaine, qui connaît depuis quelques années une intensification de son utilisation, avec une tendance poussée vers les applications à haute résolution. Ce récent mouvement ne s’accorde cependant pas avec la représentation spatiale traditionnellement homogène apportée par les automates cellulaires réguliers qui dictent généralement la structure spatiale des systèmes de géosimulation. Les problématiques soulevées dans la littérature font notamment état d’un raisonnement spatial déficient et du manque de réalisme de la représentation spatiale. Les rares solutions qui, à ce jour, dévient du dogme de la régularité dans la représentation spatiale font également l’objet de plusieurs critiques. C’est dans ce contexte que nous proposons une solution alternative multi-échelles s’appuyant sur le diagramme Voronoï de polygones et s’adaptant aux entités géographiques de l’environnement urbain.
Le modèle théorique proposé a été développé, puis expérimenté dans un contexte applicatif de géosimulation urbaine employant des données spatiales à haute résolution, sous la forme de parcelles cadastrales de formes et de tailles irrégulières. Les premiers résultats de l’approche mise en œuvre démontrent le potentiel du modèle conçu dans un contexte de géosimulation urbaine.
Pour terminer, et en s’appuyant sur l’analyse étendue des différentes approches de découpage de l’espace que nous avons effectuée dans le cadre de notre travail de recherche, nous jetons les bases d’une méthode schématique de choix du découpage spatial d’une application de géosimulation urbaine.Similar to the intensive developments in Geographic Information Systems (GIS) and spatial databases, the field of urban geosimulation was increasingly used in recent years, with an emphasis on high-resolution applications. This recent tendency does not agree however with the traditionally homogeneous spatial representation provided by regular cellular automata which are commonly used as the spatial structures of geosimulation applications. Several issues are raised in the literature, including reports of limitations in spatial reasoning and a lack of realism related to such spatial representations. The few solutions that, so far, deviate from the ‘dogma of regularity of the spatial representation’ are also subject to recent criticism. In this context, we propose an alternative multi-scale model based on the Voronoi diagram of polygons, which matches geographic features of the urban environment. The proposed theoretical model was developed and tested in the context of a urban geosimulation using high resolution spatial data, in the form of registered parcels of irregular shapes and sizes. The first results of the approach demonstrate the potential of our model in the context of urban geosimulation. Finally, based on our extensive analysis of the main approaches of space segmentation, we propose a schematic method to choose a spatial decomposition suited to urban geosimulation.
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Flodin, Hans, Gustav Friberg, and Fredrik Wahlberg. "Trajectory Planning for a Rigid Body Based on Voronoi Tessellation and Linear-Quadratic Feedback Control." Thesis, KTH, Optimeringslära och systemteori, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-118351.
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When a rigid body moves in 3-dimensional space, it is of interest to nd a trajectory such that it avoids obstacles. With this report, we create an algorithm that nds such a trajectory for a 6- DOF rigid body. For this trajectory, both the rotation and translation of the rigid body are included. This is a trajectory planning problem in the space of Euclidean transformations SE(3). Because of the complexity of this problem, we divide it into two consecutive parts where the rst part comprises translational path planning in the 3-dimensional Euclidean space and the rotational path planning. The second part comprises the design of control laws in order to follow the designed trajectory. In the rst part we create virtual spheres surrounding each obstacle in order to obtain approximate central points for each obstacle, which are then used as input for our augmented Voronoi tessellation method. We then create a graph containing all feasible paths along the faces of the convex polytopes containing the central points of the virtual spheres. A simple global graph-search algorithm is used to nd the shortest path between the nodes of the polytopes, which is then further improved by approximately 3%. Where random obstacles are uniformly distributed in a conned space. During the work process, we discovered that our translational path planning method easily could be generalized to be used in n-dimensional space. In the second part, the control law for the rigid body such that it follows the rotation and translation trajectory is designed to minimize the cost, which is done by creating a Linear-Quadratic feedback loop for a linear system. The translational control is designed in an inertial reference frame and the rotational control is designed in a body frame, rigidly attached to the rigid body's center of mass. This allows us to separate the control laws for the translational and rotational systems. The rotational system is a nonlinear system and has been linearized to be able to use the Linear-Quadratic feedback controller. All this resulted in a well performing algorithm that would nd and track a feasible trajectory as long as a feasible path exists.
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Balasuriya, Sumitha. "A computational model of space-variant vision based on a self-organised artificial retina tessellation." Thesis, University of Glasgow, 2006. http://theses.gla.ac.uk/4934/.
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DUPUIS, Franck. "Tessellations de Voronoï appliquées aux structures protéiques." Phd thesis, Université Paris-Diderot - Paris VII, 2003. http://tel.archives-ouvertes.fr/tel-00006058.
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Une tessellation de Voronoï est un moyen de diviser l'espace 3D en régions associées avec chaque élément d'un ensemble discret de points dans le but de caractériser leurs relations topologiques. Le processus associe à chacun de ces éléments un polyèdre, appelé cellule de Voronoï, défini par les intersections des plans de contact construits à mi chemin entre les points. Chaque cellule contient donc le voisinage le plus proche du point qui lui est associé et ses faces définissent les contacts avec ses plus proches voisins. Pour un ensemble donné de points, la décomposition en cellules de Voronoï est unique et absolue car il n'y a pas d'espace vide entre les cellules. De plus les caractéristiques des cellules telles que le nombre de face, le volume etc. sont des sources d'information utiles pour étudier l'organisation des points dans l'espace. Pour les structures protéiques deux échelles d'investigation peuvent être envisagées. Le niveau atomique qui est le plus représenté dans la littérature associe chaque cellule avec chaque atome ou groupe d'atomes présent dans la structure. Le second niveau associe chacune des cellules avec chaque résidu représenté par un point pouvant être un atome réel (le carbone alpha par exemple) ou un point virtuel comme le centre géométrique de la chaîne latérale. Le travail de thèse présenté ici décrit ces dernières tessellations tout d'abord d'un point de vue mathématique puis de manière plus concrète en l'appliquant aux structures protéiques et en étudiant les diverses propriétés des cellules. Deux applications concrètes sont ensuite présentées. La première est une étude statistique de la proximité des extrémités N terminale et C terminale des chaînes polypeptidiques, la seconde est une procédure d'attribution des structures secondaires régulières.
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Mohammad, Hossein Fallah Mostafa. "Coordinated Deployment of Multiple Autonomous Agents in Area Coverage Problems with Evolving Risk." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33164.
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Coordinated missions with platoons of autonomous agents are rapidly becoming popular because of technological advances in computing, networking, miniaturization and combination of electromechanical systems. These multi-agents networks coordinate their actions to perform challenging spatially-distributed tasks such as search, survey, exploration, and mapping. Environmental monitoring and locational optimization are among the main applications of the emerging technology of wireless sensor networks where the optimality refers to the assignment of sub-regions to each agent, in such a way that a suitable coverage metric is maximized. Usually the coverage metric encodes a distribution of risk defined on the area, and a measure of the performance of individual robots with respect to points inside the region of interest. The risk density can be used to quantify spatial distributions of risk in the domain.
The solution of the optimal control problem in which the risk measure is not time varying is well known in the literature, with the optimal con figuration of the robots given by the centroids of the Voronoi regions forming a centroidal Voronoi tessellation of the area. In other words, when the set of mobile robots converge to the corresponding centroids of the Voronoi tessellation dictated by the coverage metric, the coverage itself is maximized.
In this work, it is considered a time-varying risk density evolving according to a diffusion equation with varying boundary conditions that quantify a time-varying risk on the border of the workspace. Boundary conditions model a time varying flux of external threats coming into the area, averaged over the boundary length, so that rather than considering individual kinematics of incoming threats it is considered an averaged, distributed effect. This approach is similar to the one commonly adopted in continuum physics, in which kinematic descriptors are averaged over spatial domain and suitable continuum fields are introduced to describe their evolution. By adopting a first gradient constitutive relation between the flux and the density, a simple diffusion equation is obtained. Asymptotic convergence and optimality of the non-autonomous system are studied by means of Barbalat's lemma and connections with varying boundary conditions are established. Some criteria on time-varying boundary conditions and evolution are established to guarantee
the stabilities of agents' trajectories. A set of numerical simulations illustrate theoretical results.
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Sammari, Hédia. "Développement d’une méthode d’automate cellulaire basé sur une tessellation irrégulière et hiérarchique pour la simulation des processus spatiotemporels." Doctoral thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/25793.
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Les systèmes d’information géographique (SIG) sont largement utilisés pour représenter, gérer et analyser les données spatiales dans plusieurs disciplines incluant les géosciences, l’agriculture, la foresterie, la météorologie et l’océanographie. Néanmoins, malgré l’avancement récent des technologies des SIG, ils sont encore limités dans la représentation et la simulation des processus spatiotemporels. Ce travail de recherche définit le cadre théorique, conceptuel et applicatif qui vise à améliorer les méthodes de compréhension, de représentation et de simulation des processus dynamiques continus. Il vise plus précisément à améliorer les structures de données dans les SIG en développant une structure de données hiérarchique qui est la base d’un automate cellulaire capable de répondre aux principales caractéristiques de ces processus. L’exploration du potentiel des automates cellulaires pour simuler et représenter les processus dynamiques continus dans les SIG en respectant leur caractère irrégulier et hiérarchique fait l’objet de ce travail de recherche dans lequel une application dans le contexte hydrologique est mise en place. Nos objectifs spécifiques se résument dans 1) la construction d’une tessellation irrégulière et hiérarchique permettant de représenter les processus spatiotemporels et 2) la simulation de ces processus en utilisant un automate cellulaire opérant sur cette tessellation. Nous étudions la discrétisation de l’espace en tessellation irrégulière basée sur le diagramme de Voronoï et nous proposons une procédure de hiérarchisation de cette tessellation dans un objectif de représentation multi-échelle afin d’offrir une solution d’aide à la décision dans la gestion du territoire. Nous expliquons notre méthodologie et les algorithmes de sélection de données pour la génération de différents niveaux d’échelles spatiales. Un automate cellulaire non traditionnel est mis en place pour lequel nous définissons une grille à géométrie irrégulière de type Voronoï, des règles de transition spécifiques et un type particulier de voisinage orienté. Nous validons le fonctionnement de ce prototype dans le Bassin Expérimental de la Forêt Montmorency à Québec où des comparaisons sont possibles grâce à des données de débits d’eau mesurées in situ.Geographic information systems (GIS) are widely used to represent, manage and analyse spatial data in many disciplines including geosciences, agriculture, forestry, meteorology and oceanography. However, despite recent advances in GIS technologies, they are still limited when it comes to representation and simulation of spatiotemporal processes. This research work, deals with a theoretical, conceptual and practical framework which aims to improve the representation of dynamic continuous processes. It aims especially to improve GIS capabilities by developing a CA based on a hierarchical irregular tessellation which is able to take into account the main characteristics of these processes. The exploration of the cellular automata potential to simulate and represent dynamic continuous processes regarding their irregular and hierarchic characteristics is the subject of this work where an application in the hydrologic field is established. Our specific objectives are 1) to build an irregular and hierarchic grid that can be used to represent spatiotemporal processes, 2) to simulate those processes with a cellular automata operating on this grid. We give details about the irregular geometric grid based on a Voronoï Diagram, the characteristics of a specific oriented neighbourhood and the transition rules that are governing the cells update. In addition, we discuss the hierarchical perspective of the build lattice that is essential for easy move between different spatial scales. We explain our methodology of data selection in order to generate the spatial levels of representation by demonstrating the used selection algorithms. This facilitates the representation of spatial dynamic phenomena and contributes to the better understanding of the complex behaviour of the whole system at different levels of details. We also present the data structures and general functioning of the whole simulation system. We finally, validate our framework by simulating the water flow process in a specific watershed in the region of Montmorency Forest of Quebec where in situ data are available. To validate our simulation results we compare them with measured data.
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Ghazi, Arash. "Microstructural computational modeling of the mechanical behaviour of closed-cell foams: from tessellation-based to CT scan-based modeling." Doctoral thesis, Universite Libre de Bruxelles, 2020. https://dipot.ulb.ac.be/dspace/bitstream/2013/306841/3/Thesis.pdf.
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The mechanical behavior of closed cell metallic foams strongly depends on their geometry at the scale of cells and cell walls. Two approaches are proposed in this work to address this computationally:(i) a controlled geometrical description of foam morphology features by exploiting an advanced tessellation-based procedure, allowing to generate realistic microstructural geometry,(ii) a procedure allowing to extract geometrical features of a foam morphology based on image-based modelling using CT scans. The first approach proposes a methodology that allows the automated generation of RVEs with a detailed control of the microstructure, including of cell geometries. It is primarily based on an inclusions packing algorithm assisted by distance fields control. Such distance fields can subsequently be used to morph inclusions, producing generalized tessellations with the possibility of incorporating curved and irregular boundaries. 3D morphologies of closed cell foams are produced by extracting the geometry from a proper combination of distance field functions. The procedure allows controlling the cell size distribution, spatial cell wall thickness distribution (correlated or not with the cell size distribution), wall curvatures and/or defects. An automated 3D meshing tool for implicit geometries was exploited to produce high quality tetrahedral meshes from the generated implicit foam geometries. Representative volume element based simulations were performed using this approach to assess the different morphological features relative importance on the mechanical behaviour of ALPORAS. An original extension of this tool was incorporating the transformation of 3D geometry into a shell-based finite element model. This resulted in a significant gain in computation time and allowed for simulating compression test up to densification (being out of reach with 3D solid finite element models) showing a good qualitative match with experimental results from the literature.The second approach proposes a robust methodology for the automated generation of shell-based finite element models directly from X-ray Computed Tomography (CT) scans.An in situ X-ray CT compression test of the sample was performed to serve as basis of comparison to the computations. As first steps, raw CT images are segmented using various image processing techniques and an implicit 3D geometry is reconstructed for each cell by using a Euclidean distance field computation technique. An automated geometrical procedure is used next to extract a (surface) shell geometry from this implicit 3D geometry, followed by subsequent meshing step. A direct comparison of the performed simulations with raw experimental data is performed. The detailed deformation and failure mechanisms of closed-cell foams under quasi static uniaxial compressive loading are investigated numerically and compared directly with the result of the in situ experimental measurement.Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished
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Andersson, Jonas. "Silhouette-based Level of Detail : A comparison of real-time performance and image space metrics." Thesis, Blekinge Tekniska Högskola, Institutionen för datalogi och datorsystemteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-12755.
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Context. The geometric complexity of objects in games and other real-time applications is a crucial aspect concerning the performance of the application. Such applications usually redraw the screen between 30-60 times per second, sometimes even more often, which can be a hard task in an environment with a high number of geometrically complex objects. The concept called Level of Detail, often abbreviated LoD, aims to alleviate the load on the hardware by introducing methods and techniques to minimize the amount of geometry while still maintaining the same, or very similar result. Objectives. This study will compare four of the often used techniques, namely Static LoD, Unpopping LoD, Curved PN Triangles, and Phong Tessellation. Phong Tessellation is silhouette-based, and since the silhouette is considered one of the most important properties, the main aim is to determine how it performs compared to the other three techniques. Methods. The four techniques are implemented in a real-time application using the modern rendering API Direct3D 11. Data will be gathered from this application to use in several experiments in the context of both performance and image space metrics. Conclusions. This study has shown that all of the techniques used works in real-time, but with varying results. From the experiments it can be concluded that the best technique to use is Unpopping LoD. It has good performance and provides a good visual result with the least average amount of popping of the compared techniques. The dynamic techniques are not suitable as a substitute to Unpopping LoD, but further research could be conducted to examine how they can be used together, and how the objects themselves can be designed with the dynamic techniques in mind.
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Evans, Thomas. "Deployable and Foldable Arrays of Spatial Mechanisms." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5321.
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This work evaluates a specific origami device known as the kaleidocycle and the broad classof rigidly foldable origami. Both of these have potential for application in the design of deployableand foldable arrays of spatial mechanisms.Origami is considered a compliant mechanisms because it achieves its motion through thedeflection of paper creases. Compliant mechanisms generally do not allow for continuous rotation;however, the compliant kaleidocycle represents an exception to this generality. Along with theirability to rotate continuously, kaleidocycles may also be designed to exhibit multistable behaviorduring this rotation. These two characteristics make the kaleidocycle an interesting device withpotential for applications in engineering. This work presents the multistable characteristics ofkaleidocycles, showing that devices can be made which exhibit one, two, three, or four distinctstable equilibrium positions. Kaleiocycles may also be designed to exhibit a range over which thedevice is neutrally stable.The second type of origami presented in this work is rigidly foldable origami, a special classof origami in which all deflection occurs at the creases, allowing the panels to remain rigid. Thistype of origami is of particular interest because of its ability to be constructed from materials muchstiffer than paper while retaining its mobility. This property allows rigidly foldable origami to beapplied to fields such as architecture and deployable mechanisms. This work presents a method forevaluating rigid foldability in origami tessellations. This method is used to define seven theoremsfor the rigid foldability of origami twists and to develop new rigidly foldable origami “gadgets”and tessellations.
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Findley, Tara M. "An Experimental Analysis of Auxetic Folded Cores for Sandwich Structures Based on Origami Tessellations." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1372862614.
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Alqasimi, Ahmad. "Design Of Shape Morphing Structures Using Bistable Elements." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5897.
Full textAbstract:
This dissertation presents new concepts and methodology in designing shape-morphing structures using bistable elements. Developed using the Pseudo-Rigid-Body Model (PRBM), linear bistable compliant mechanism elements produce predictable and controllable length changes. Step-by-step design procedures are developed to guide the design process of these bistable elements. Two different examples of Shape-Morphing Space Frames (SMSFs) were designed and prototyped utilizing the bistable linear elements in a single-layer grid, in addition to flexures and rigid links, to morph a cylindrical space frame into both a hyperbolic and a spherical space frame. Moreover, bistable unit-cell compliant-mechanism elements were also developed to morph a compact structure from a specific initial shape to a final specific shape. The detailed design of those unit cells were done using Computer-aided design (CAD) software following a novel design procedure to transform a one-degree-of-freedom mechanism into a structure with sufficient compliance within its links to toggle between two chosen stable positions. Two different design examples were investigated in this research and prototyped to demonstrate the ability to morph disks into a hemisphere or a sphere with the structure being stable in both states (disk and sphere).
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Oropallo, William Edward Jr. "A Point Cloud Approach to Object Slicing for 3D Printing." Thesis, University of South Florida, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10751757.
Full textAbstract:
Various industries have embraced 3D printing for manufacturing on-demand, custom printed parts. However, 3D printing requires intelligent data processing and algorithms to go from CAD model to machine instructions. One of the most crucial steps in the process is the slicing of the object. Most 3D printers build parts by accumulating material layers by layer. 3D printing software needs to calculate these layers for manufacturing by slicing a model and calculating the intersections. Finding exact solutions of intersections on the original model is mathematically complicated and computationally demanding. A preprocessing stage of tessellation has become the standard practice for slicing models. Calculating intersections with tessellations of the original model is computationally simple but can introduce inaccuracies and errors that can ruin the final print.
This dissertation shows that a point cloud approach to preprocessing and slicing models is robust and accurate. The point cloud approach to object slicing avoids the complexities of directly slicing models while evading the error-prone tessellation stage. An algorithm developed for this dissertation generates point clouds and slices models within a tolerance. The algorithm uses the original NURBS model and converts the model into a point cloud, based on layer thickness and accuracy requirements. The algorithm then uses a gridding structure to calculate where intersections happen and fit B-spline curves to those intersections.
This algorithm finds accurate intersections and can ignore certain anomalies and error from the modeling process. The primary point evaluation is stable and computationally inexpensive. This algorithm provides an alternative to challenges of both the direct and tessellated slicing methods that have been the focus of the 3D printing industry.
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Medeiros, Margarete Farias. "Geometria dinâmica no ensino de transformações no plano : uma experiência com professores da educação básica." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/54888.
Full textAbstract:
Nesta dissertação apresentamos a concepção, implementação e validação de uma proposta para o ensino de transformações geométricas no plano usando o ambiente de geometria dinâmica GeoGebra. A proposta integra Geometria e Arte através da construção de pavimentações do plano e de mosaicos de Escher e foi dirigida para professores do ensino fundamental, tendo como objetivo apresentar uma nova alternativa de trabalho na Geometria escolar e também capacitá-los para o uso de mídias digitais nas suas salas de aula. O trabalho foi desenvolvido dentro dos princípios da Engenharia Didática. Na análise e validação da implementação da proposta tomamos como base a teoria Sócio-Histórica, cuja referência principal é a obra de Vygotsky; também utilizamos o trabalho de Duval sobre registros de representação semiótica no processo de aprendizagem da Matemática. A partir das análises a priori e a posteriori observamos que os professores participantes da oficina, através do uso do GeoGebra, se apropriaram dos princípios da geometria dinâmica e dos conceitos da geometria das transformações.This work presents the conception, implementation and validation of an experiment to teach geometric transformations in the plane using the dynamic geometry environment GeoGebra. The proposal integrates geometry and art through the construction of tessellations of the plane, including Escher's mosaics, and it was directed to elementary school teachers, aiming to present a new alternative to work with geometry using digital media. The work used the principles of Didactic Engineering and the analysis of the experiment was based on the Socio-Historical theory, whose main reference is the work of Vygotsky and on the work of Duval about registers of semiotic representation in the process of mathematics learning. The analysis a priori and a posteriori showed that the teachers, through the use of GeoGebra, learned the principles of dynamic geometry and the concepts of geometry transformations.
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Lundström, Emrik. "Vector Displacement Mapping." Thesis, Blekinge Tekniska Högskola, Institutionen för kreativa teknologier, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-4416.
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Kontext: Displacement Mapping är en teknik som används inom 3D-spel för att skapa detaljrikedom i geometri utan att behöva triangelobjekt bestående av oönskad geometrikomplexitet. Tekniken har även andra användningsområden i 3D-spel, till exempel terränggeometri. Tekniken skänker detaljrikedom genom att i samband med tesselering förskjuta geometri i en normalriktning eller längs annan specificerad riktning. Vector Displacement Mapping är en teknik liknande Displacement Mapping där skillnaden är att Vector Displacement Mapping förskjuter geometri i tre dimensioner. Mål: Syftet med arbetet är utforska Vector Displacement Mapping i sammanhanget 3D-Spel och att antyda att tekniken kan användas i 3D-spel likt Displacement Mapping. Arbetet jämför Vector Displacement Mapping med Displacement Mapping för att urskilja skillnader i exekveringstid mellan teknikernas centrala skillnader. Skillnaderna i exekveringstid ställs i kontrast mot diskussion av teknikernas grafikminnesanvändning. Metoder: Jämförelsen baseras på en implementation av de båda teknikerna tillsammans med tesselering. Prestandamätningar genereras med implementationen som grund. Implementationen använder sig av Direct3D 11. Resultat: Resultatet som erhålls genom jämförelsen visar att exekveringstiderna mellan teknikernas centrala skillnader varierar svagt. Grafikminnesanvändningen mellan teknikerna skiljer sig med en faktor 3 eller en faktor 4 där Vector Displacement Mapping använder mer grafikminne. Slutsatser: Slutsatser som dras baserat på resultatet är att Vector Displacement Mapping i situationer där överhängande geometri är ett önskat resultat kan ersätta Displacement Mapping. Vidare diskussion förs kring slutsatser, avgränsningar och framtida forskning som arbetet berör.
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Choi, John. "Counting Vertices in Isohedral Tilings." Scholarship @ Claremont, 2012. https://scholarship.claremont.edu/hmc_theses/28.
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An isohedral tiling is a tiling of congruent polygons that are also transitive, which is to say the configuration of degrees of vertices around each face is identical. Regular tessellations, or tilings of congruent regular polygons, are a special case of isohedral tilings. Viewing these tilings as graphs in planes, both Euclidean and non-Euclidean, it is possible to pose various problems of enumeration on the respective graphs. In this paper, we investigate some near-regular isohedral tilings of triangles and quadrilaterals in the hyperbolic plane. For these tilings we enumerate vertices as classified by number of edges in the shortest path to a given origin, by combinatorially deriving their respective generating functions.
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Yazdan, Panah Arian. "Nonuniform Coverage with Time-Varying Risk Density Function." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33007.
Full textAbstract:
Multi-agent systems are extensively used in several applications. An important class of applications involves the optimal spatial distribution of a group of mobile robots on a given area, where the optimality refers to the assignment of subregions to the robots, in such a way that a suitable coverage metric is maximized. Typically the coverage metric encodes a risk distribution defined on the area, and a measure of the performance of individual robots with respect to points inside the region of interest. The coverage metric will be maximized when the set of mobile robots configure themselves as the centroids of the Voronoi tessellation dictated by the risk density. In this work we advance on this result by considering a generalized area control problem in which the coverage metric is non-autonomous, that coverage metric is time varying independently of the states of the robots. This generalization is motivated by the study of coverage control problems in which the coordinated motion of a set of mobile robots accounts for the kinematics of objects penetrating from the outside. Asymptotic convergence and optimality of the non-autonmous system are studied by means of Barbalat's Lemma, and connections with the kinematics of the moving intruders is established. Several numerical simulation results are used to illustrate theoretical predictions.
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Dubrowski, Piotr. "An automated multicolour fluorescence in situ hybridization workstation for the identification of clonally related cells." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/733.
Full textAbstract:
The methods presented in this study are aimed at the identification of subpopulations (clones) of genetically similar cells within tissue samples through measurement of loci-specific Fluorescence in-situ hybridization (FISH) spot signals for
each nucleus and analyzing cell spatial distributions by way of Voronoi tessellation and Delaunay triangulation to robustly define cell neighbourhoods.
The motivation for the system is to examine lung cancer patient for
subpopulations of Non-Small Cell Lung Cancer (NSCLC) cells with biologically meaningful gene copy-number profiles: patterns of genetic alterations statistically
associated with resistance to cis-platinum/vinorelbine doublet chemotherapy treatment.
Current technologies for gene-copy number profiling rely on large amount of cellular
material, which is not always available and suffers from limited sensitivity to only the
most dominant clone in often heterogeneous samples. Thus, through the use of FISH, the
detection of gene copy-numbers is possible in unprocessed tissues, allowing identification of specific tumour clones with biologically relevant patterns of genetic aberrations.
The tissue-wide characterization of multiplexed loci-specific FISH signals,
described herein, is achieved through a fully automated, multicolour fluorescence imaging microscope and object segmentation algorithms to identify cell nuclei and FISH spots within. Related tumour clones are identified through analysis of robustly defined cell neighbourhoods and cell-to-cell connections for regions of cells with homogenous
and highly interconnected FISH spot signal characteristics.
This study presents experiments which demonstrate the system’s ability to
accurately quantify FISH spot signals in various tumour tissues and in up to 5 colours
simultaneously or more through multiple rounds of FISH staining. Furthermore, the
system’s FISH-based cell classification performance is evaluated at a sensitivity of 84% and specificity 81% and clonal identification algorithm results are determined to be comparable to clone delineation by a human-observer. Additionally, guidelines and procedures to perform anticipated, routine analysis experiments are established.