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Dissertations / Theses on the topic 'Triangulation'
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Below, Alexander. "Complexity of triangulation /." [S.l.] : [s.n.], 2002. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=14672.
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Pihlström, Max. "Visual representation by triangulation." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-264109.
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n this thesis the triangulation is treated as a general-purpose visual representation by investigation of various domain-specific methods such as triangulation interpolation, mesh flows, vertex neighborhood feature measures and re-triangulation for spatial transformations. Suggested new methods include an effective cost for image interpolation based on work by Sederberg et al. and a ridge-edge measure related to the Harris edge detector.
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Trisiripisal, Phichet. "Image Approximation using Triangulation." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/33337.
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An image is a set of quantized intensity values that are sampled at a finite set of sample points on a two-dimensional plane. Images are crucial to many application areas, such as computer graphics and pattern recognition, because they discretely represent the information that the human eyes interpret. This thesis considers the use of triangular meshes for approximating intensity images. With the help of the wavelet-based analysis, triangular meshes can be efficiently constructed to approximate the image data. In this thesis, this study will focus on local image enhancement and mesh simplification operations, which try to minimize the total error of the reconstructed image as well as the number of triangles used to represent the image. The study will also present an optimal procedure for selecting triangle types used to represent the intensity image. Besides its applications to image and video compression, this triangular representation is potentially very useful for data storage and retrieval, and for processing such as image segmentation and object recognition.<br>Master of Science
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Mankiewicz, Piotr, Carsten Schuett, and schuett@math uni-kiel de. "On the Delone Triangulation Numbers." ESI preprints, 2000. ftp://ftp.esi.ac.at/pub/Preprints/esi952.ps.
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Benderius, Björn. "Laser Triangulation Using Spacetime Analysis." Thesis, Linköping University, Department of Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-10522.
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<p>In this thesis spacetime analysis is applied to laser triangulation in an attempt to eliminate certain artifacts caused mainly by reflectance variations of the surface being measured. It is shown that spacetime analysis do eliminate these artifacts almost completely, it is also shown that the shape of the laser beam used no longer is critical thanks to the spacetime analysis, and that in some cases the laser probably even could be exchanged for a non-coherent light source. Furthermore experiments of running the derived algorithm on a GPU (Graphics Processing Unit) are conducted with very promising results.</p><p>The thesis starts by deriving the theory needed for doing spacetime analysis in a laser triangulation setup taking perspective distortions into account, then several experiments evaluating the method is conducted.</p>
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Kyle, Stephen Alexander. "Triangulation methods in engineering measurement." Thesis, University College London (University of London), 1988. http://discovery.ucl.ac.uk/1318061/.
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Industrial surveying and photogrammetry are being increasingly applied to the measurement of engineering objects which have typical dimensions in the range 2-100 metres. Both techniques are examples of the principle of triangulation. By applying photocrammetric concepts to surveying methods and vice-versa, a general approach is established which has a number of advantages. In particular. alternative strategies for constructing and analysing measurement networks are developed. These should help to strengthen the geometry and simplify the analysis. The primary results concern the use of non-levelled theodolites, which have applications on board floating objects, and three new suggestions for controlling and computing relative orientations in photogrammetry. These involve reciprocal observations with theodolites. the photographing of linear scales defined by three target points and employing cameras which have been levelled. As a secondary result, some consideration Is given to automation, and instrument design. It is suggested that polarimetry could be successfully applied to improve the transfer of orientation in confined situations, such as in mining. In addition, the potential use of electronic cameras as photo-theodolites is discussed.
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Jaw, Jen-Jer. "Control surface in aerial triangulation /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu148818889444039.
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Potter, John R. "Pseudo-triangulations on closed surfaces." Worcester, Mass. : Worcester Polytechnic Institute, 2008. http://www.wpi.edu/Pubs/ETD/Available/etd-021408-102227/.
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Pelegris, Gerasimos. "A triangulation method for passive ranging." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA284180.
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Thesis (M.S. in Electrical Engineering and M.S. in Applied Physics)--Naval Postgraduate School, June 1994.<br>Thesis advisor(s): Pieper, Ron J. ; Cooper, Wlfred W. "June 1994." Includes bibliographical references. Also available online.
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Lemaire, Christophe. "Triangulation de Delaunay et arbres multidimensionnels." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 1997. http://tel.archives-ouvertes.fr/tel-00850521.
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Les travaux effectués lors de cette thèse concernent principalement la triangulation de Delaunay. On montre que la complexité en moyenne - en termes de sites inachevés - du processus de fusion multidimensionnelle dans l'hypothèse de distribution quasi-uniforme dans un hypercube est linéaire en moyenne. Ce résultat général est appliqué au cas du plan et permet d'analyser de nouveaux algorithmes de triangulation de Delaunay plus performants que ceux connus à ce jour. Le principe sous-jacent est de diviser le domaine selon des arbres bidimensionnels (quadtree, 2d-tree, bucket-tree. . . ) puis de fusionner les cellules obtenues selon deux directions. On étudie actuellement la prise en compte de contraintes directement pendant la phase de triangulation avec des algorithmes de ce type. De nouveaux algorithmes pratiques de localisation dans une triangulation sont proposés, basés sur la randomisation à partir d'un arbre binaire de recherche dynamique de type AVL, dont l'un est plus rapide que l'algorithme optimal de Kirkpatrick, au moins jusqu'à 12 millions de sites K Nous travaillons actuellement sur l'analyse rigoureuse de leur complexité en moyenne. Ce nouvel algorithme est utilisé pour construire " en-ligne " une triangulation de Delaunay qui est parmi les plus performantes des méthodes " en-ligne " connues à ce jour.
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Henry, G. K. "Three dimensional vision by laser triangulation." Thesis, University of Bath, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384100.
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Silva, Luis Fernando Maia Santos. "Merging meshes using dynamic regular triangulation." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/25512.
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Malhas simpliciais são utilizadas em várias áreas da Computação Gráfica e Engenharia, como por exemplo, em vizualização, simulação, prototipação, além de outras aplicações. Este tipo de malha é, geralmente, utilizada como aproximações discretas de espaços contínuos, onde eles oferecem representações flexíveis e eficientes. Muito esforço é gasto visando gerar malhas de boa qualidade, porém, em alguns casos as malhas acabam sendo modificadas. Entretanto, este tipo de operação é geralmente custosa e inflexível, o que pode resultar na geraão de malhas bem diferentes das originais. A habilidade de manipular cenas dinâmicas revela-se um dos problemas mais desafiadores da computação gráfica. Este trabalho propõe um método alternativo para atualizar malhas simpliciais que vai além de mudanças geométricas e topológicas. Tal método explora uma das propriedade das Tringulações de Delaunay com Pesos, que permite a usá-las para definir implicitamente as relações de conectividade de uma malha. Ao contrário de manter as informações de conectividade explicitamente, a atual abordagem simplesmente armazena uma coleção de pesos associados a cada vértice. Além disso, criamos um algoritmo para calcular uma Tringulação de Delaunay com Pesos a partir de uma dada triangulação. O algoritmo consiste em uma busca em largura que atribui pesos aos vértices, e uma estratégia de de subdivisão para assegurar que a triangulação reconstruída será correspondente à original. Este método apresenta diversas aplicações e, em particular, permite a criação de um sistema simples de realizar combinação entre triangulações, que será ilustrada com exemplos em 2D e 3D.<br>Simplicial meshes are used in many fields of Computer Graphics and Engineering, for instance, in visualization, simulation, prototyping, among other applications. This kind of mesh is often used as discrete approximations of continuous spaces, where they offer flexible and efficient representations. Considerable effort is spent in generating good quality meshes, but in some applications the meshes can be modified over time. However, this kind of operation is often very expensive and inflexible, sometimes leading to results very different from the original meshes. The ability to handle dynamic scenes reveals itself as one of the most challenging problems in computer graphics. This work proposes an alternative technique for updating simplicial meshes that undergo geometric and topological changes. It explores the property that a Weighted Delaunay Triangulation (WDT) can be used to implicitly define the connectivity of a mesh. Instead of explicitly maintaining connectivity information, this approach simply keeps a collection of weights associated to each vertex. It consists of an algorithm to compute a WDT from any given triangulation, which relies on a breadth-first traversal to assign weights to vertices, and a subdivision strategy to ensure that the reconstructed triangulation conforms with the original one. This technique has many applications and, in particular, it allows for a very simple method of merging triangulations, which is illustrated with both 2D and 3d examples.
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Veillet, Isabelle. "Triangulation spatiale de bloc d'images SPOT." Observatoire de Paris, 1991. https://hal.archives-ouvertes.fr/tel-02095460.
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Outre la qualité de ses images, l'atout majeur du système SPOT est sa précision géométrique. Cette étude a pour objet d'évaluer l'apport d'une triangulation de bloc au traitement géométrique d'images SPOT, afin de traiter globalement la géométrie de l'ensemble des images d'un chantier de spatiocartographie. Tant l'intérêt réel du calcul de blocs que sa faisabilité sont ici démontrés. Au préalable, il est indispensable d'analyser la modélisation de la prise de vues SPOT. Une modélisation simple, robuste et proche de la réalité physique de la prise de vues SPOT est proposée. Avec un nombre restreint de points d'appui, l'exactitude obtenue reste inférieure à 10 mètres en planimétrie et 6 mètres en altimétrie, ce qui est conforme à la plupart des standards de cartographie à l'échelle du 1:50000. Sans point d'appui, une précision de 15 mètres a été obtenue sur des blocs couvrant 200 km x 200 km<br>Besides its image quality, the main advantage of Sport system is its geometric accuracy. The aim of this study is the evaluation of what block adjustment can bring to Spot images geometric processing, in order to process together all the images of a space mapping project. The actual advantage of this kind of computation is shown here. Before, a model of the image-ground relationship must be given. The proposed model is simple, robust and close to the physical image acquisition. With very few control points, the resulting accuracy is less than 10 meters in planimetry, and 6 meters in altimetry. These figures fit most standards of 1:50000 scale topographic maps. Without any ground control point, the accuracy is 15 meters on 200 km x 200 km area
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James, Steven Michael. "Triangulation and the Problem of Objectivity." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1316500581.
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Nicander, Torun. "Indoor triangulation system using vision sensors." Thesis, Uppsala universitet, Signaler och system, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-429676.
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This thesis aims to investigate a triangulation system for indoor positioning in two dimensions (2D). The system was implemented using three Pixy2 vision sensors placed on a straight baseline. A Pixy2 consists of a camera lens and an image sensor (Aptina MT9M114) as well as a microcontroller (NXP LPC4330), and other components. It can track one or multiple colours, or a combination of colours. To position an object using triangulation, one needs to determine the angles (α) to the object from a pair of known observing points (i.e., any pair of the three Pixy2s' placed in fixed positions on the baseline in this project). This is done from the Pixy2s' images. Using the Pinhole Camera Model, the tangent of the angle, tan(α), is found to have a linear relation with the displacement Δx in the image plane (in pixels), namely, tan(α) = k Δx, where k is a constant depending on the specific Pixy2. A wooden test board was made specially to determine k for all the Pixy2s. It had distance marks made in two dimensions and had a Pixy2 affixed at the origin. By placing a coloured object at three different sets of spatial sampling points (marks), the constant k for each Pixy2 was determined with the error variance of < 5%. Position estimations of the triangulation system were conducted using all three pairs formed from the three Pixy2s and placing the positioned object at different positions in the 2D plane on the board. A combination using estimation values from all three pairs to make a more accurate estimate was also evaluated. The estimation results show the positioning accuracy ranging from 0.03678 cm to 2.064 cm for the z-coordinate, and from 0.02133 cm to 0.9785 cm for the x-coordinate, which are very satisfactory results. The vision sensors were quite sensitive to the light environment when finely tuned to track one object, which therefore has a significant effect on the performance of the vision sensor-based triangulation. An extension of the system to use more than three Pixy2s has been looked into and shown to be feasible. A method for auto-calibrating the Pixy2s' positions on the baseline was suggested and implemented. After auto-calibration, the system still performed satisfactory position estimations.
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Morris, Todd D. (Todd Douglas) Carleton University Dissertation Engineering Electrical. ""VLSI triangulation processing for machine vision."." Ottawa, 1987.
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Norström, Christer. "Underwater 3-D imaging with laser triangulation." Thesis, Linköping University, Department of Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6125.
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<p>The objective of this master thesis was to study the performance of an active triangulation system for 3-D imaging in underwater applications. Structured light from a 20 mW laser and a conventional video camera was used to collect data for generation of 3-D images. Different techniques to locate the laser line and transform it into spatial coordinates were developed and evaluated. A field- and a laboratory trial were performed.</p><p>From the trials we can conclude that the distance resolution is much higher than the lateral- and longitudinal resolution. The lateral resolution can be improved either by using a high frame rate camera or simply by using a low scanning speed. It is possible to obtain a range resolution of less than a millimeter. The maximum range of vision was 5 meters under water measured on a white target and 3 meters for a black target in clear sea water. These results are however dependent on environmental and system parameters such as laser power, laser beam divergence and water turbidity. A higher laser power would for example increase the maximum range.</p>
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Kakarlapudi, Geetha. "Analysis of beacon triangulation in random graphs." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1447.
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Our research focusses on the problem of finding nearby peers in the Internet.
We focus on one particular approach, Beacon Triangulation that is widely used to
solve the peer-finding problem. Beacon Triangulation is based on relative distances
of nodes to some special nodes called beacons. The scheme gives an error when a
new node that wishes to join the network has the same relative distance to two or
more nodes. One of the reasons for the error is that two or more nodes have the
same distance vectors. As a part of our research work, we derive the conditions to
ensure the uniqueness of distance vectors in any network given the shortest path
distribution of nodes in that network. We verify our analytical results for G(n, p)
graphs and the Internet. We also derive other conditions under which the error in the
Beacon Triangulation scheme reduces to zero. We compare the Beacon Triangulation
scheme to another well-known distance estimation scheme known as Global Network
Positioning (GNP).
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Engman, Robin. "HPA* Used With a Triangulation-Based Graph." Thesis, Blekinge Tekniska Högskola, Institutionen för kreativa teknologier, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-5630.
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Context: Pathfinding is an important phase when it comes to AI. The AI needs to know how to get from one point to another when there are obstacles ahead. For that reason, different pathfinding algorithms have been created. Objective: In this paper a new pathfinding algorithm, THPA*, is described, and it will also be compared to the more common algorithms, A*, and HPA* which THPA* is based on. Methods: These algorithms are then tested on an extensive array of maps with different paths and the results consisting of the execution times will be compared against each other. Results: The result of those tests conclude that THPA* performs better in terms of execution time in the average case; however it does suffer from low quality paths. Conclusions: This paper concludes that THPA* is a promising algorithm albeit in need of more refinement to make up for the negative points.
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Pihlström, Max. "The triangulation as an alternative painting medium." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-208830.
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In as much as raster and vector graphics have complementary roles in digital imagery they both have limitations. In this paper, the two frameworks are in part bridged in the triangulation mesh where in particular the ideas of the spatial neighborhood and representation by geometrical primitives are combined. With a triangulation algorithm for preserving integrity of contour and color together with methods for introducing geometric detail and blending color, the end result is a configurable medium with qualities resembling those of physical paint, demonstrating potential as a viable alternative for graphics creation.
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Borouchaki, Houman. "Graphe de connexion et triangulation de delaunay." Paris 7, 1993. http://www.theses.fr/1993PA077127.
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Une methode generale est presentee pour determiner l'enveloppe convexe d'un ensemble fini de points dans r#d. Pour definir la structure faciale d'un d-polytope, un nouveau graphe, dit de connexion, est introduit; il permet d'eviter les tris effectues pour la mise a jour des relations d'adjacence a chaque etape d'insertion de point; en ce sens cette methode fournit un automate pour la resolution du probleme. Cette methode est appliquee a une construction de l'i-dag propose par boissonnat et al. Les deux algorithmes sont de complexite optimale, en temps d'execution, dans leur version randomisee. Nous appliquons le concept de graphe de connexion au probleme de la triangulation d'un nuage de points, simple et de delaunay. Ce graphe nous libere de l'obligation usuelle d'inclure le nuage de points dans un ou plusieurs simplexes englobants pour ne traiter que des points internes a la triangulation. Les cas degeneres sont aussi traites. Nous proposons un algorithme dynamique pour resoudre le probleme de la triangulation de delaunay sous contraintes dans r#2; cet algorithme realise l'insertion et la suppression de points et d'aretes; il utilise les proprietes de convexite des triangulations; il presente l'avantage d'etre recursif. L'algorithme introduit est adapte a la resolution des problemes d'evolution, ou les points et les aretes contraintes peuvent etre deplaces. Une extension a r#3 est basee sur l'ajout de points dans les faces contraintes. Une implementation en pascal a permis de verifier l'efficacite de notre methode pour resoudre des problemes de contraintes poses dans r#2 et r#3
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Anderson, Ryan J. "Triangulation between Elderly Parents And Adult Children." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd904.pdf.
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Lam, Alice. "3D sound-source localization using triangulation-based methods." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/63551.
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The localization of sound sources in a reverberant environment, such as a classroom or industrial workspace, is an essential first step toward noise control in these spaces. Many sound source localization techniques have been developed for use with microphone arrays. A common characteristic of these techniques is that they are able to provide the direction from which the sound is coming, but not the range (i.e. the distance between the source and receiver).This thesis presents two triangulation-based methods for localizing sound sources in 3D space, including range, using a small hemispherical microphone array. Practical issues with the hemispherical array, such as source resolution and operating frequency limitations, are discussed. The first method - direct triangulation - involves taking multiple sound field measurements at different locations in the room, and then using the combined output of all receivers to triangulate the source. Direct triangulation is conceptually simple and requires no a priori knowledge of the surrounding environment, but proves cumbersome as multiple array measurements are required - this also limits its application to steady-state noise sources. The second method - image source triangulation - requires only one measurement, instead taking into account the early specular reflections from the walls of the room to create "image receivers" from which the source location can be triangulated. Image source triangulation has the advantage of only requiring one measurement and may be more suited to small spaces such as meeting rooms. However, it relies on having accurate pre-knowledge of the room geometry in relation to the microphones. Both triangulation methods are evaluated using simulations and physical in-room measurements, and are shown to be able to localize simple monopole sources in reverberant rooms.<br>Applied Science, Faculty of<br>Mechanical Engineering, Department of<br>Graduate
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Ebadi, Hamid. "A comprehensive study on GPS assisted aerial triangulation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq24534.pdf.
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König, Sören, and Stefan Gumhold. "Robust Surface Triangulation of Points with Normal Information." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-131385.
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The problem of generating a surface triangulation from a set of points with normal information arises in several mesh processing tasks like surface reconstruction or surface resampling. In this paper we present a surface triangulation approach which is based on local 2d delaunay triangulations in tangent space. Our contribution is the extension of this method to surfaces with sharp corners and creases. We demonstrate the robustness of the method on difficult meshing problems that include nearby sheets, self intersecting non manifold surfaces and noisy point samples.
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Sheehy, Damian James. "Medial surface computation using a domain Delaunay triangulation." Thesis, Queen's University Belfast, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239226.
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Chou, George Tao-Shun. "Large-scale 3D reconstruction : a triangulation-based approach." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/86296.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.<br>Includes bibliographical references (p. [153]-157).<br>by George Tao-Shun Chou.<br>Ph.D.
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Jayawardena, D. P. W. "The role of triangulation in spatial data handling." Thesis, Keele University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385666.
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König, Sören, and Stefan Gumhold. "Robust Surface Triangulation of Points with Normal Information." Technische Universität Dresden, 2013. https://tud.qucosa.de/id/qucosa%3A27382.
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The problem of generating a surface triangulation from a set of points with normal information arises in several mesh processing tasks like surface reconstruction or surface resampling. In this paper we present a surface triangulation approach which is based on local 2d delaunay triangulations in tangent space. Our contribution is the extension of this method to surfaces with sharp corners and creases. We demonstrate the robustness of the method on difficult meshing problems that include nearby sheets, self intersecting non manifold surfaces and noisy point samples.
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Gholizadeh, Behrouz. "Représentation par triangulation de la surface d'objets tridimensionnels." Paris 11, 1985. http://www.theses.fr/1985PA112336.
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Dans cette thèse nous avons développé deux méthodes d’approximation des surfaces d'objets 3D dont la surface est échantillonnée par une centaine de milliers de points. Ces points sont répartis selon un maillage régulier de méridiens et de parallèles. Dans un premier temps nous nous sommes ramenés à une méthode assez simple de compression d'information par triangulation de l'objet à partir des coupes parallèles ou des coupes méridiennes. Cette technique est de mise en œuvre très simple, de coût informatique limité mais ses performances tant en compression qu'en fidélité de représentation sont également limitées. Nous avons développé ensuite une méthode beaucoup plus générale d'approximation progressive de la surface d'objet 3D. Dans cette méthode un polyèdre de départ est au préalable choisi. Les faces du polyèdre sont alors récursivement partagées selon une stratégie qui nous permet de contrôler le nombre de facettes constituant la représentation ainsi que la qualité géométrique de cette représentation. (De très bons résultats ont été obtenus sur des objets variés avec un nombre de facettes variant de 1000 à 12000)<br>In this thesis have two methods been developed for the approximation of 3D object surfaces. These surfaces are sampled with several hundreds of thousands of points which are located on a regular lattice of meridian and parallel lines ln a first approach, we limited ourselves to a method of data compression in which triangulation of the abject is derived from slices of parallels and meridians. This technic is inexpensive, easy to implement but suffers from limited performances (compression ratio and accuracy of representation). The second method we next developed makes use of progressive polyhedral approximation of 3D object surfaces. In this method we begin with an initial polyhedron, the triangular facets of which are recursively split with a strategy that allows the control of not only the number of facets in the representation but also the geometric quality of this representation Very good results have been obtained with various objects and different numbers of facets ranging from 1000 to 12 000
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Linden, Timothy R. "A Triangulation-Based Approach to Nonrigid Image Registration." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1310502150.
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Boström, Viktor. "Positioning and tracking using image recognition and triangulation." Thesis, Uppsala universitet, Signaler och system, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-448110.
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Triangulation is used in a wide range of applications of position estimation. Usually it is donebymeasuring angles by hand to estimate positions in land surveying, navigation and astronomy.Withthe rise of image recognition arises the possibility to triangulate automatically. The aim ofthis thesisis to use the image recognition camera Pixy2 to triangulate a target i threedimensions. It is basedon previous projects on the topic to extend the system to estimatepositions over a larger spaceusing more Pixy2s. The setup used five Pixy2s with pan-tilt kitsand one Raspberry Pi 4 B. Somelimitations to the hardware was discovered, limiting the extentof the space in which triangulationcould be successfully performed. Furthermore, there weresome issues with the image recognitionalgorithm in the environment positioning was performed.The thesis was successful in that it managesto triangulate positions over a larger area thanprevious projects and in all three dimensions. Thesystem could also follow a target’s trajectory,albeit, there were some gaps in the measurements.
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Kihl, Hilma, and Simon Källberg. "Simulated Laser Triangulation with Focus on Subsurface Scattering." Thesis, Linköpings universitet, Medie- och Informationsteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-178132.
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Practical laser triangulation sessions were performed for each measurement object to obtain ground truth data. Three methods for laser line simulations were implemented: reshaping the built-in light sources of Blender, creating a texture projector and approximating a Gaussian beam as a light emitting volume. The camera simulation was based on the default camera of Blender together with settings from the physical camera. Three approaches for creating wood material were tested: procedural texturing, using microscopic image textures to create 3D-material and UV-mapping high resolution photograph onto the geometry. The blister package was simulated with one material for the pills and another for the semi-transparent plastic packaging. A stand-alone Python script was implemented to simulate anisotropic/directed subsurface scattering of a point laser in wood. This algorithm included an approach for creating vector fields that represented subsurface scattering directions. Three post-processing scripts were produced to simulate sensor noise, blurring/blooming of the laser line and lastly to apply simulated speckle patterns to the laser lines. Sensor images were simulated by rendering a laser line projected onto a measurement object. The sensor images were post-processed with the three mentioned scripts. Thousands of sensor images were simulated, with a small displacement of the measurement object between each image. After post-processing, these images were combined to a single scattering image. SICK IVP AB provided the algorithms needed for laser centre extraction as well as for scattering image creation.<br><p>Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet</p>
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Su, Dan. "Pixel level data-dependent triangulation with its applications." Thesis, University of Bath, 2003. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426147.
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Collier, Jeff. "Examining laser triangulation system performance using a software simulation." Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1176837151.
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Malek, Alaeddin. "The numerical approximation of surface area by surface triangulation /." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65498.
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Rila, Luciano. "Coding of still images using irregular subsampling and triangulation." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268025.
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余康煒 and Hong-wai Yue. "Image morphing based on compatible triangulation and mesh interpolation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31222122.
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Lattuada, Roberto. "A triangulation based approach to three dimensional geoscientific modelling." Thesis, Birkbeck (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312757.
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Parwana, Sudheer Singh. "Surface triangulation and the downstream effects on surface flattening." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1606/.
Full textAbstract:
Surface triangulation is an active area of research due to its wide usage in a range of different computer aided applications, including computer aided design (CAD), manufacture (CAM) and finite element analysis (FEA). Although these applications are used to create, interrogate, manipulate and analyse surfaces, internally they actually approximate the surface geometry using a triangulation and then operate on the triangles, making them triangulation dependant algorithms. However, despite the reliance on the triangulation by the downstream application, there is very little work which has been focused on the inherent affects of the underlying triangulation on the performance or result of the application. Therefore, the impact of the triangulation on the downstream application is still not well known or defined. This thesis investigates triangulation and the downstream effects on the triangulation dependant method of surface flattening. Two novel topics are explored, notably right angle triangulation configurations (RATCs) and axis of minimum principal curvature (AMPC) influenced triangulations, each which was found to have an impact on the triangulation dependant method of surface flattening. Right angle triangles (RATs) are commonly used throughout surface flattening. However, given a set of uniformly sampled points, there are many different ways in which the diagonals can be placed to form a final triangulation consisting of RATs. These different configurations of edges are introduced as RATCs. To investigate the effects of RATCs on surface flattening, three global configurations are proposed; regular, diamond and chevron. In addition, local variations of RATCs are explored by fitting RATCs that best approximated the local Gaussian curvature of the original surface. Also considered is the influence of triangulation developability and its effects on flattening. Developable surfaces should flatten without inducing any area or shape distortion. However, it is shown that the transfer of this developabilty information from the surface to the triangulation can be lost. It is established that skewing the vertices of a triangulation so that no triangle edges followed along the AMPC, causes the flattening to induce distortion. As the shape of a triangulation is defined by its edges, if no edges follow along the AMPC, this means that the triangulation will not inherit this shape characteristic. Therefore, a new method is proposed to triangulate a surface, whilst ensuring that one edge of every triangle follows along the general direction of the AMPC. This thesis also introduces a new efficient and robust parametric trimmed surface triangulation method. Efficiency is gained during trimmed curve tracing by minimising the number of cells processed. Key features are the efficient tracing algorithm and knowledge of orientation of the trimming curves is not required. This approach also minimises the occurrence of degenerate triangles and copes with holes independently of the grid size.
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Horeau, Mathieu. "Raison et absolu : histoire d'une triangulation (Kant, Hegel, Kierkegaard)." Paris 1, 2011. http://www.theses.fr/2011PA010537.
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Notre thèse examine la manière dont Kierkegaard a su s'approprier les grandes interrogations de la tradition philosophique à partir d'un ensemble de problèmes constitués sur le sol de l'idéalisme allemand. II s'agit de savoir si l'achèvement hégélien de la métaphysique n'accomplit la philosophie que pour en faire un dogmatisme supérieur. En identifiant la raison et l'absolu, que Kant avait radicalement dissociés, Hegel surmonte toute dévaluation sceptique du discours philosophique. Mais à quel prix ? Réactivant certains arguments kantiens sans pourtant faire retour à Kant, la pensée paradoxale de Kierkegaard ressaisit les rapports dialectiques de la raison et de l'absolu pour conjurer l'hubris de la spéculation autant que l'insuffisance du formalisme transcendantal. Nous travaillons donc à défendre Kierkegaard en tant que philosophe, la destination authentiquement religieuse de l'oeuvre ne devant pas occulter sa portée philosophique, qui concerne notre époque.
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Lau, Yan Nam. "Adaptive approach to triangulation of isosurface in volume data /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?COMP%202002%20LAUY.
Full textAbstract:
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.<br>Includes bibliographical references (leaves 91-95). Also available in electronic version. Access restricted to campus users.
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Yue, Hong-wai. "Image morphing based on compatible triangulation and mesh interpolation /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20731590.
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Hogan, William Robertson Sean. "An efficient method for finding the Delaunay triangulation of randomly scattered data with applications in contour plotting /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1994.
Find full textAbstract:
Thesis (Ph.D.)--Tufts University, 1994.<br>Submitted to the Dept. of Electrical Engineering. Includes bibliographical references (leaves 69-70). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Iordanov, Iordan. "Delaunay triangulations of a family of symmetric hyperbolic surfaces in practice." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0010.
Full textAbstract:
La surface de Bolza est la surface hyperbolique orientable compacte la plus symétrique de genre 2. Pour tout genre supérieur à 2, il existe une surface orientable compacte construite de manière similaire à la surface de Bolza et ayant le même type de symétries. Nous appelons ces surfaces des surfaces hyperboliques symétriques. Cette thèse porte sur le calcul des triangulations de Delaunay (TD) de surfaces hyperboliques symétriques. Les TD de surfaces compactes peuvent être considérées comme des TD périodiques de leur revêtement universel (dans notre cas, le plan hyperbolique). Une TD est pour nous un complexe simplicial. Cependant, les ensembles de points ne définissent pas tous une décomposition simpliciale d'une surface hyperbolique symétrique. Dans la littérature, un algorithme a été proposé pour traiter ce problème avec l'utilisation de points factices : initialement une TD de la surface est construite avec un ensemble de points connu, puis des points d'entrée sont insérés avec le célèbre algorithme incrémental de Bowyer, et enfin les points factices sont supprimés, si la triangulation reste toujours un complexe simplicial. Pour la surface de Bolza, les points factices sont spécifiés. L'algorithme existant calcule une DT de la surface de Bolza comme une DT périodique du plan hyperbolique, ce qui nécessite de travailler dans un sous-ensemble approprié du plan hyperbolique. Nous étudions les propriétés des TD de la surface de Bolza définies par des ensembles de points contenants l'ensemble proposé de points factices, et nous décrivons en détail une implémentation de l'algorithme incrémentiel pour cette surface. Nous commençons par définir un représentant canonique unique qui est contenu dans un sous-ensemble borné du plan hyperbolique pour chaque face d'une TD de la surface. Nous donnons une structure de données pour représenter une TD de la surface de Bolza via les représentants canoniques de ses faces. Nous détaillons les étapes de la construction d'une telle triangulation et les opérations supplémentaires qui permettent de localiser les points et de retirer des sommets. Nous présentons également les résultats sur le degré algébrique des prédicats nécessaires pour toutes les opérations. Nous fournissons une implémentation entièrement dynamique pour la surface de Bolza, en offrant l'insertion de nouveaux points, la suppression des sommets existants, la localisation des points, et la construction d'objets duaux. Notre implémentation est basée sur la bibliothèque CGAL (Computational Geometry Algorithms Library), et est actuellement en cours de révision pour être intégrée dans la bibliothèque. L'intégration de notre code dans CGAL nécessite que tous les objets que nous introduisons soient compatibles avec le cadre existant et conformes aux standards adoptés par la bibliothèque. Nous donnons une description détaillée des classes utilisées pour représenter et traiter les triangulations hyperboliques périodiques et les objets associés. Des analyses comparatives et des tests sont effectués pour évaluer notre implémentation, et une application simple est donnée sous la forme d'une démonstration CGAL. Nous discutons une extension de notre implémentation à des surfaces hyperboliques symétriques de genre supérieur à 2. Nous proposons trois méthodes pour engendrer des ensembles de points factices pour chaque surface et présentons les avantages et les inconvénients de chaque méthode. Nous définissons un représentant canonique contenu dans un sous-ensemble borné du plan hyperbolique pour chaque face d'une TD de la surface. Nous décrivons une structure de données pour représenter une telle triangulation via les représentants canoniques de ses faces, et donnons des algorithmes pour l'initialisation de la triangulation. Enfin, nous discutons une implémentation préliminaire dans laquelle nous examinons les difficultés d'avoir des prédicats exacts efficaces pour la construction de TD de surfaces hyperboliques symétriques<br>The Bolza surface is the most symmetric compact orientable hyperbolic surface of genus 2. For any genus higher than 2, there exists one compact orientable surface constructed in a similar way as the Bolza surface having the same kind of symmetry. We refer to this family of surfaces as symmetric hyperbolic surfaces. This thesis deals with the computation of Delaunay triangulations of symmetric hyperbolic surfaces. Delaunay triangulations of compact surfaces can be seen as periodic Delaunay triangulations of their universal cover (in our case, the hyperbolic plane). A Delaunay triangulation is for us a simplicial complex. However, not all sets of points define a simplicial decomposition of a symmetric hyperbolic surface. In the literature, an algorithm has been proposed to deal with this issue by using so-called dummy points: initially a triangulation of the surface is constructed with a set of dummy points that defines a Delaunay triangulation of the surface, then input points are inserted with the well-known incremental algorithm by Bowyer, and finally the dummy points are removed, if the triangulation remains a simplicial complex after their removal. For the Bolza surface, the set of dummy points to initialize the triangulation is given. The existing algorithm computes a triangulation of the Bolza surface as a periodic triangulation of the hyperbolic plane and requires to identify a suitable subset of the hyperbolic plane in which to work. We study the properties of Delaunay triangulations of the Bolza surface defined by sets of points containing the proposed set of dummy points, and we describe in detail an implementation of the incremental algorithm for it. We begin by identifying a subset of the hyperbolic plane that contains at least one representative for each face of a Delaunay triangulation of the surface, which enables us to define a unique canonical representative in the hyperbolic plane for each face on the surface. We give a data structure to represent a Delaunay triangulation of the Bolza surface via the canonical representatives of its faces in the hyperbolic plane. We detail the construction of such a triangulation and additional operations that enable the location of points and the removal of vertices. We also report results on the algebraic degree of predicates needed for all operations. We provide a fully dynamic implementation for the Bolza surface, supporting insertion of new points, removal of existing vertices, point location, and construction of dual objects. Our implementation is based on CGAL, the Computational Geometry Algorithms Library, and is currently under revision for integration in the library. To incorporate our code into CGAL, all the objects that we introduce must be compatible with the existing framework and comply with the standards adopted by the library. We give a detailed description of the classes used to represent and handle periodic hyperbolic triangulations and related objects. Benchmarks and tests are performed to evaluate our implementation, and a simple application is given in the form of a CGAL demo. We discuss an extension of our implementation to symmetric hyperbolic surfaces of genus higher than 2. We propose three methods to generate sets of dummy points for each surface and present the advantages and shortcomings of each method. We identify a suitable subset of the hyperbolic plane that contains at least one representative for each face of a Delaunay triangulation of the surface, and we define a canonical representative in the hyperbolic plane for each face on the surface. We describe a data structure to represent such a triangulation via the canonical representatives of its faces, and give algorithms for the initialization of the triangulation with dummy points. Finally, we discuss a preliminary implementation in which we examine the difficulties of having efficient exact predicates for the construction of Delaunay triangulations of symmetric hyperbolic surfaces
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Pébay, Philippe. "Delaunay-admissiblité en dimensions 2 et 3." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2000. http://tel.archives-ouvertes.fr/tel-00607168.
Full textAbstract:
La méthode des éléments finis, largement utilisée en analyse numérique, requiert que le domaine considéré soit préalablement maillé, c'est-à-dire partitionné en un ensemble de polytopes généralement, mais pas nécessairement, simpliciaux. Parmi les méthodes permettant la génération de tels maillages, la triangulation de Delaunay présente le double intérêt d'avoir un support théorique fondant la robustesse des algorithmes, ainsi que de produire des éléments de qualité, conditionnant fortement la précision des calculs ultérieurs. Elle présente cependant l'inconvénient de ne pas être à même de prendre en compte des considérations topologiques, lui interdisant de facto d'être utilisée en l'état pour produire des maillages. Un certain nombre de méthodes ont été proposées pour tenter de résoudre ce problème, mais aucune ne constitue une solution générale. Par ailleurs, les maillages qu'elles restituent ne possèdent plus la propriété de Delaunay. Ce travail étudie les conditions dans lesquelles une contrainte, en dimensions 2 et 3, apparaîtra dans toute triangulation de Delaunay du nuage de points auquel elle est associée. En particulier, des théorèmes de Delaunay-admissibilité a priori sont établis. A l'aide de ces résultats, des algorithmes de redéfinition de contraintes sont proposés, de telle sorte que les nouvelles discrétisations, recouvrements des anciennes, soient construites par toute triangulation de Delaunay. Ainsi, les contraintes étant satisfaites automatiquement, aucune opération de forçage a posteriori n'est requise, et les maillages produits sont de Delaunay. En raison du coût prohibitif de la convergence en dimension 3, deux algorithmes efficaces sont proposés, sans qu'aucune conjecture sur leur convergence ne soit formulée. A titre d'application de la méthode en dimension 3, l'interfaçage avec un mailleur de Delaunay contraint existant est étudié. En particulier, la pertinence de la méthode est illustrée grâce au déblocage d'une configuration que ce mailleur ne parvient pas à résoudre. D'autres applications possibles, ainsi que les développements en cours sont également évoqués.
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Pébay, Philippe. "Delaunay-admissibilité a priori en dimensions 2 et 3." Paris 6, 2000. http://www.theses.fr/2000PA066588.
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Kaykobad, M. Tanvir. "Transforming Plane Triangulations by Simultaneous Diagonal Flips." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40499.
Full textAbstract:
We explore the problem of transforming plane triangulations using simultaneous
diagonal flips. Wagner showed that any n-vertex plane triangulation can be transformed to any other plane triangulation on equal number of vertices using a finite
sequence of diagonal flips. Later on it has been established that O(n) individual flips
suffice to complete this transformation. Bose et al. showed that the transformation
can also be done in 4 × (
2 /
log 54/53
+ 2 /
log 6/5
) logn + 2 ≈ 327.1 log n simultaneous flips. This
bound is asymptotically tight.
We present two algorithms to improve the leading coefficient of this bound for
transforming any plane triangulation into any other. The first of the two algorithms
lowers this bound down to 4 × (
2 /
log 12/11
+ 2 /
log 9/7
) logn + 2 ≈ 85.8 log n. By processing
and preprocessing the interior and exterior of the triangulation’s Hamiltonian cycle
parallelly in an interlaced fashion, we make further improvement of the algorithm
from ≈ 327.1 log n down to 12 /
log 6/5
logn + 2 ≈ 45.6 log n.
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Bridges, Monte Lee. "Superintendent evaluation for increased organizational performance : from traits to triangulation /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/7813.
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Forest, Collado Josep. "New Methods for Triangulation-based Shape Acquisition using Laser Scanners." Doctoral thesis, Universitat de Girona, 2004. http://hdl.handle.net/10803/7730.
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Tradicionalment, la reproducció del mon real se'ns ha mostrat a traves d'imatges planes. Aquestes imatges se solien materialitzar mitjançant pintures sobre tela o be amb dibuixos. Avui, per sort, encara podem veure pintures fetes a ma, tot i que la majoria d'imatges s'adquireixen mitjançant càmeres, i es mostren directament a una audiència, com en el cinema, la televisió o exposicions de fotografies, o be son processades per un sistema computeritzat per tal d'obtenir un resultat en particular. Aquests processaments s'apliquen en camps com en el control de qualitat industrial o be en la recerca mes puntera en intel·ligència artificial. Aplicant algorismes de processament de nivell mitja es poden obtenir imatges 3D a partir d'imatges 2D, utilitzant tècniques ben conegudes anomenades Shape From X, on X es el mètode per obtenir la tercera dimensió, i varia en funció de la tècnica que s'utilitza a tal nalitat. Tot i que l'evolució cap a la càmera 3D va començar en els 90, cal que les tècniques per obtenir les formes tridimensionals siguin mes i mes acurades. Les aplicacions dels escàners 3D han augmentat considerablement en els darrers anys, especialment en camps com el lleure, diagnosi/cirurgia assistida, robòtica, etc. Una de les tècniques mes utilitzades per obtenir informació 3D d'una escena, es la triangulació, i mes concretament, la utilització d'escàners laser tridimensionals. Des de la seva aparició formal en publicacions científiques al 1971 [SS71], hi ha hagut contribucions per solucionar problemes inherents com ara la disminució d'oclusions, millora de la precisió, velocitat d'adquisició, descripció de la forma, etc. Tots i cadascun dels mètodes per obtenir punts 3D d'una escena te associat un procés de calibració, i aquest procés juga un paper decisiu en el rendiment d'un dispositiu d'adquisició tridimensional. La nalitat d'aquesta tesi es la d'abordar el problema de l'adquisició de forma 3D, des d'un punt de vista total, reportant un estat de l'art sobre escàners laser basats en triangulació, provant el funcionament i rendiment de diferents sistemes, i fent aportacions per millorar la precisió en la detecció del feix laser, especialment en condicions adverses, i solucionant el problema de la calibració a partir de mètodes geomètrics projectius.<br>Traditionally, the reproduction of the real world has been shown to us by means of at images. These images used to be materialised by means of paint on canvas, drawings or the like. Today, we still see hand made pictures, by fortune, although most of the images are acquired by cameras and they are either directly shown to an audience, like in the cinema, television or photographs, or they are processed by a computer system in order to obtain a particular result, like in industrial quality assurance or bleeding edge artificial intelligence research. Applying mid-level processing algorithms, 3D images can be obtained from 2D ones, using well known techniques called Shape From X, where X is the method for obtaining the 3rd dimension. While the evolution to the 3D camera begun in the 90s, the techniques for obtaining the most accurate 3D shape need to be continuously improving. The application of 3D scanners has spread signi cantly in the recent years, specially in elds like entertainment, assisted diagnosis/ surgery, robotics, etc. One of the most used techniques to obtain 3D information from a scene is triangulation, and more concretely, triangulationbased laser scanners. Since their formal appearance in scienti c publications, in 1971 [SS71], there have been contributions for solving inherent problems like occlusion avoidance, accuracy improvement, acquisition speed, shape description, etc. All of the methods for obtaining 3D points of a scene is accompained with a calibration procedure, and this procedure plays a decisive role in the performance of the acquisition device. The goal of this thesis is to provide a holistic approach to the problem of shape acquisition, giving a wide survey of triangulation laser scanners, testing the performance of di erent systems, and to give contributions for both improving acquisition accuracy under adverse conditions and solving the calibration problem. In addition, the calibration approach is based on previous works that used projective geometry to this end.