Shape processing defines a set of theoretical and algorithmic tools for creating, measuring and modifying digital representations of shapes.  Such tools are of paramount importance to many disciplines of computer graphics, including modeling, animation, visualization, and image processing.  Many applications of shape processing can be found in the entertainment and medical industries. In an attempt to improve upon many previous shape processing techniques, the present thesis explores the theoretical and algorithmic aspects of a difference measure, which involves fitting a ball (disk in 2D and sphere in 3D) so that it has at least one tangential contact with each shape and the ball interior is disjoint from both shapes. We propose a set of ball-based operators and discuss their properties, implementations, and applications.  We divide the group of ball-based operations into unary and binary as follows: Unary operators include: * Identifying details (sharp, salient features, constrictions) * Smoothing shapes by removing such details, replacing them by fillets and roundings * Segmentation (recognition, abstract modelization via centerline and radius variation) of tubular structures Binary operators include: * Measuring the local discrepancy between two shapes * Computing the average of two shapes * Computing point-to-point correspondence between two shapes * Computing circular trajectories between corresponding points that meet both shapes at right angles * Using these trajectories to support smooth morphing (inbetweening) * Using a curve morph to construct surfaces that interpolate between contours on consecutive slices The technical contributions of this thesis focus on the implementation of these tangent-ball operators and their usefulness in applications of shape processing. We show specific applications in the areas of animation and computer-aided medical diagnosis.  These algorithms are simple to implement, mathematically elegant, and fast to execute.

The research in the thesis investigates the use of minimal path techniques to track and detect cracks, modeled as curves, in critical infrastructure like pavements and bridges. We developed a novel minimal path algorithm to detect curves with complex topology that may have both closed cycles and open sections using an arbitrary point on the curve as the sole input. Specically, we applied the novel algorithm to three problems: semi-automatic crack detection, detection of continuous cracks for crack sealing applications and detection of crack growth in structures like bridges. The current state of the art minimal path techniques only work with prior knowledge of either both terminal points or one terminal point plus total length of the curve. For curves with multiple branches, all terminal points need to be known. Therefore, we developed a new algorithm that detects curves and relaxes the necessary user input to one arbitrary point on the curve. The document presents the systematic development of this algorithm in three stages. First, an algorithm that can detect open curves with branches was formulated. Then this algorithm was modied to detect curves that also have closed cycles. Finally, a robust curve detection algorithm was devised that can increase the accuracy of curve detection. The algorithm was applied to crack images and the results of crack detection were validated against the ground truth. In addition, the algorithm was also used to detect features like catheter tube and optical nerves in medical images. The results demonstrate that the algorithm is able to accurately detect objects that can be modeled as open curves.

Thèse de doctorat : Mathématiques : Tours : 2008. / Titre provenant de l'écran-titre.

Der Ziel dieser Arbeit ist der Hausdorff Konvergenz der Juliamengen zu beweisen, als wir eine Familie von ganzen transzendenten Funktionen, die ein einziges Bakergebiet enthalten, approximieren. Als erstes geben wir eine vollständige dynamische Beschreibung der approximierenden transzendenten Funktionen und zeigen die Existenz von invarianten Gebiete unter der Iterierte. Insbesondere besitzen die approximierenden Funktionen ein Attraktionsgebiet, das gegen das Bakergebiet als Kernel im Sinn von Carathéodory konvergiert. Letztlich beweisen wir Hausdorff Konvergenz auf zwei Wege. Einerseits zeigen wir unter bestimmten Bedingungen der Fatoumenge der Grenzfunktion die Hausdorff Konvergenz der Juliamengen. Anderseits zeigen wir unter verschiedenen Bedingungen der Fatoumenge der Grenzfunktion die Hausdorff Konvergenz der ausgefüllten Juliamengen, die bezüglich der Bakergebiet oder der Attraktionsgebiet definiert sind.

We look from a new point of view at the definition and basic properties of the Lebesgue measure and integral on Euclidean spaces, on abstract spaces, and on locally compact Hausdorff spaces. We use mini sums to give all of them a unified treatment that is more efficient than the standard ones. We also give Fubini's theorem a proof that is nicer and uses much lighter technical baggage than the usual treatments.

With technological advances digital video and imaging are becoming more and more relevant. Medical, remote-learning, surveillance, conferencing and home monitoring are just a few applications of these technologies. Along with compression, there is now a need for analysis and extraction of data. During the days of film and early digital cameras the processing and manipulation of data from such cameras was transparent to the end user. This transparency has been decreasing and the industry is moving towards `smart users' - people who will be enabled to program and manipulate their video and imaging systems. Smart cameras can currently zoom, refocus and adjust lighting by sourcing out current from the camera itself to the headlight. Such cameras are used in the industry for inspection, quality control and even counting objects in jewelry stores and museums, but could eventually allow user defined programmability. However, all this will not happen without interactive software as well as capabilities in the hardware to allow programmability. In this research, compression, expansion and detail extraction from videos in the surveillance arena are addressed. Here, a video codec is defined that can embed contextual details of a video stream depending on user defined requirements creating a video summary. This codec also carries out motion based segmentation that helps in object detection. Once an object is segmented it is matched against a database using its shape and color information. If the object is not a good match, the user can either add it to the database or consider it an anomaly. RGB vector angle information is used to generate object descriptors to match objects to a database. This descriptor implicitly incorporates the shape and color information while keeping the size of the database manageable. Color images of objects that are considered `safe' are taken from various angles and distances (with the same background as that covered by the camera is question) and their RGB vector angle based descriptors constitute the information contained in the database. This research is a first step towards building a compression and detection system for specific surveillance applications. While the user has to build and maintain a database, there are no restrictions on the size of the images, zoom and angle requirements, thus, reducing the burden on the end user in creating such a database. This also allows use of different types of cameras and doesn't need a lot of up-front planning on camera location, etc.

Thesis (Ph.D.)--York University, [2004]. Graduate Programme in [Mathematics]. / Typescript. Includes bibliographical references (leaves 163-166). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ99158

University, Diss., 2004--Heidelberg.

Codensity monads are ubiquitous, as are various different notions of compactness and finiteness. Two such examples of "compact" spaces are compact Hausdorff Spaces and Linearly Compact Vector Spaces. Compact Hausdorff Spaces are the algebras of the codensity monad induced by the inclusion of finite sets in the category of sets. Similarly linearly compact vector spaces are the algebras of the codensity monad induced by the inclusion of finite dimensional vector spaces in the category of vector spaces. So in these two examples the notions of finiteness, compactness and codensity are intertwined. In this thesis we generalise these results. To do this we generalise the notion of ultrafilter, and follow the intuition of the compact Hausdorff case. We give definitions of general notions of "finiteness" and "compactness" and show that the algebras for the codensity monad induced by the "finite" objects are exactly the "compact" objects.

O objetivo deste trabalho é mostrar a existência de uma função contínua que é não-diferenciável em todo ponto. Seguiremos aqui a exposição de H. Katsuura (Amer. Math. Monthly (1991)) e que utiliza conceitos como sistemas de funções iteradas (iterated function systems) e o espaço de Hausdorff de subconjuntos compactos de um espaco métrico completo. Para ter uma descrição completa do assunto, vamos apresentar uma exposição sistemática de tais conceitos. Na Seção 1 apresentamos o Espaço de Hausdorff dos conjuntos compactos. Na Seção 2 mostramos que um certo sistema iterado de funções determina uma contração no espaço de Hausdorff. Finalmente na Seção 3 mostramos o exemplo de uma função contínua que não é diferenciável em nenhum ponto. No apêndice apresentamos uma breve introdução aos conceitos utilizados de espaços métricos e a prova do teorema da contração. / In this thesis we show the existence of a continuous function which is nowhere differentiable. We follow the H. Katsuura's work in Amer. Math. Month. (1991) which utilizes concepts as iterated function systems and Hausdorff space of compact subsets of a complete metric space. For having a full description of the subject, we give a systematic description of sucb concepts. In Section 1 we introduce the Hausdorff space of compact subsets. In Section 2 we sbow that some iterated function systems determines a contraction in the Hausdorff space. Finally, in Section 3, we construct an example of a continuous function nowhere differentiable. In tbe Appendix we give a breve exposi tion of some concepts in Metric Spaces and we prove Contraction Theorem.