A synthetic approach to the construction of projective geometry, its methods and selected results are given in the proposed thesis. The main historical drawbacks of the original proof of Chasles's theorem for non-developable ruled surfaces and von Staudt's formalization of projective geometry are commented. The corre- sponding theoretical background is elaborated on visual demonstrations with the accent to interrelations of classical synthetic, axiomatic and analytic points of view. Synthetic methods of projective geometry and their mixture with analytic methods are described on examples including numerous alternative proofs and generalizations of some theorems. A method of four-dimensional visualization is introduced in details. Elementary constructions of images of points, lines, planes and 3-spaces are followed by models of polychora, their sections and shadows. Chasles's theorem is proven for non-developable ruled quadrics on synthetic vi- sualizations, then generalized and proven within the pure projective framework for algebraic surfaces. The synthetic classification of regular quadrics is derived from descriptive geometry constructions of sections of four-dimensional cones and analytically verified in the projective extension of the real space. An integral part of the thesis is a...

Ce travail montre l'unité de l'œuvre de Pascal dans ce qui concerne la « comparabilité des incomparables » : la comparaison, langagière ou mathématique, qui se fait entre des choses qui ne pourraient pas en principe être rapprochées. Il s'agit de faire une approche historique et linguistique pour poser des questions philosophiques par rapport à la comparaison, notamment sur le rôle de principe que l'infini y joue selon Pascal. Nous identifions la comparaison des incomparables sous trois formes.La première partie de ce travail est consacrée à formuler une forme rhétorique d'analogie que nous nommons l'« analogie de disproportion » (nous inspirant de Secretan 1998). Si l'analogie est généralement dite faire une comparaison entre deux rapports, chacun desquels existe entre des choses homogènes, l'analogie de disproportion permet en revanche de montrer une ressemblance entre des rapports d'hétérogénéité, entre des disproportions ou entre des distances infinies: deux choses sont aussi différentes entre elles que deux autres. Pascal étant un auteur qui souligne surtout les disproportions, nous montrons qu'il compare ces disproportions, notamment pour délimiter à l'homme ce qu'il ne peut pas connaître parfaitement.La deuxième partie analyse la pratique mathématique de Pascal « en poids, nombre et mesure » : il s'agit de montrer que dans la méthode des indivisibles des Lettres de A. Dettonville, dans le Traité du triangle arithmétique et dans la comparaison du courbe et du droit, toujours l'infini (ou plutôt l'indéfini) intervient comme un facteur qui permet la comparabilité de ce qui semblait être incomparable. La troisième partie fait une discussion proprement philosophique sur l'infiniment petit et l'infiniment grand, prenant en compte la pratique mathématique de Pascal analysée dans la deuxième partie. Il est question de discuter sur la nature des « indivisibles », des « différences » et des « distances infinies ». Nous proposons que l'« infini » dans la pratique mathématique de Pascal relève plutôt de l'« indéfini », reliant cela à une distinction entre le sens absolu et le sens relatif des mots. Une exception dans la pratique mathématique de Pascal est la géométrie projective, où il faut accepter des éléments à distance infinie. La « rencontre » des deux infinis, finalement, permet de montrer la réciprocité de l'infini de grandeur et de l'infini de petitesse. Une discussion est faite à ce propos, reliant la proportion inverse entre les deux infinis à la grandeur et la petitesse de l'homme et au caractère paradoxal de certaines vérités selon Pascal, lesquelles sont résolues dans la personne du Christ. On conclut que Pascal propose non pas une connaissance directe de l'infini, mais plutôt une approche à la relation que l'homme, être fini, possède avec l'infini / This thesis shows the unity of Pascal's work in what concerns the "comparability of incomparables'': the comparison, either in mathematics our natural language, between things which could not in principle be brought together. The approach is both a historical and a linguistic one, and it aims to recovery some important questions regarding the philosophical nature of comparisons, more specifically, the role of the infinite in Pascal's thought. The comparison of incomparables may be identified in three different formsIn the first part, we formulate a rhetorical form of analogy that we call an "analogy of disproportion'' (inspired by Secretan 1998). If the analogy is generally said to make a comparison between two relations, each of which exists between homogeneous things, the analogy of disproportion, on the other hand, shows a resemblance between relations of heterogeneity, between disproportions or between infinite distances: two things may be as different from each other as any two other things. Even if disproportions are a central theme to Pascal, he did not shy away of comparing such disproportions -- in particular to delimit what man cannot know perfectly.The second part analyzes the mathematical practice of Pascal "in weight, number and measure'': it is necessary to show that in the method of indivisibles of the Lettres de A. Dettonville, in the Traité du Triangle Arithmétique and in the comparison of the curved and the straight lines, always the infinite (or rather the indefinite) intervenes as a factor that allows the comparability of what would seem to be incomparable. The third part makes a philosophical discussion on the infinitely small and the infinitely large, taking into account Pascal's mathematical practice, which was analyzed in the second part. We discuss the nature of "indivisibles'', "differences'' and "infinite distances''. We suggest that the "infinite'' in Pascal's mathematical practice is rather an "indefinite'', linking it to a distinction between the absolute and the relative meaning of words. An exception in Pascal's mathematical practice is his projective geometry, where it is necessary to accept elements at an infinite distance. The "encounter'' of the two infinites makes it possible to show the reciprocity of the infinity of greatness and the infinity of smallness. Finally, we analyze the inverse proportionality between the two infinites with regard to the greatness and the wretchedness of man and to the paradoxical nature of certain truths according to Pascal, which are concealed in the person of the Christ. The conclusion is that Pascal arrives not at a direct knowledge of the infinite, but to an approach to the relation that man, a finite being, has with the infinite

We describe a new direct method for estimating structure and motion from image intensities of multiple views. We extend the direct methods of Horn- and-Weldon to three views. Adding the third view enables us to solve for motion, and compute a dense depth map of the scene, directly from image spatio -temporal derivatives in a linear manner without first having to find point correspondences or compute optical flow. We describe the advantages and limitations of this method which are then verified through simulation and experiments with real images.

[Truncated abstract] Image transition effects are commonly used on television and human computer interfaces. The transition between images creates a perception of continuity which has aesthetic value in special effects and practical value in visualisation. The work in this thesis demonstrates that better image transition effects are obtained by incorporating properties of projective geometry into image transition algorithms. Current state-of-the-art techniques can be classified into two main categories namely shape interpolation and warp generation. Many shape interpolation algorithms aim to preserve rigidity but none preserve it with perspective effects. Most warp generation techniques focus on smoothness and lack the rigidity of perspective mapping. The affine transformation, a commonly used mapping between triangular patches, is rigid but not able to model perspective effects. Image transition techniques from the view interpolation community are effective in creating transitions with the correct perspective effect, however, those techniques usually require more feature points and algorithms of higher complexity. The motivation of this thesis is to enable different views of a planar surface to be interpolated with an appropriate perspective effect. The projective geometric relationship which produces the perspective effect can be specified by two quadrilaterals. This problem is equivalent to finding a perspectively appropriate interpolation for projective transformation matrices. I present two algorithms that enable smooth perspective transition between planar surfaces. The algorithms only require four point correspondences on two input images. ...The second algorithm generates transitions between shapes that lie on the same plane which exhibits a strong perspective effect. It recovers the perspective transformation which produces the perspective effect and constrains the transition so that the in-between shapes also lie on the same plane. For general image pairs with multiple quadrilateral patches, I present a novel algorithm that is transitionally symmetrical and exhibits good rigidity. The use of quadrilaterals, rather than triangles, allows an image to be represented by a small number of primitives. This algorithm uses a closed form force equilibrium scheme to correct the misalignment of the multiple transitional quadrilaterals. I also present an application for my quadrilateral interpolation algorithm in Seitz and Dyer's view morphing technique. This application automates and improves the calculation of the reprojection homography in the postwarping stage of their technique. Finally I unify different image transition research areas into a common framework, this enables analysis and comparison of the techniques and the quality of their results. I highlight that quantitative measures can greatly facilitate the comparisons among different techniques and present a quantitative measure based on epipolar geometry. This novel quantitative measure enables the quality of transitions between images of a scene from different viewpoints to be quantified by its estimated camera path.

[pt] A proposta deste trabalho é apresentar e demonstrar o Porismo de Poncelet, tanto o caso base para triângulos quanto o caso geral para um polígono qualquer. Sendo o Porismo de Poncelet considerado um dos mais importantes teoremas da Geometria Projetiva, serão utilizados neste trabalho conceitos de Geometria Projetiva que muitas vezes não são familiares da maioria dos professores de matemática da rede básica de ensino. O caso base para triângulos juntamente com as cônicas podem ser bem explorados no ensino médio com a utilização de software de geometria como Geogebra que foi ferramenta fundamental na elaboração das figuras utilizadas nas demonstrações apresentadas nessa dissertação. / [en] The purpose of this work is to present and demonstrate the Poncelet s Porism, both the base case for triangles and the general case for any polygon. Being the Poncelet s Porism considered one of the most important theorems of Projective Geometry, we will use concepts of Projective Geometry that are not often familiar to most mathematics teachers in the basic teaching network. The base case for triangles together with the conics can be well explored in high school with the use of geometry software such as Geogebra that was a fundamental tool in the elaboration of the figures used in the demonstrations presented in this essay.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In the present work, we tried to investigate the conics in the synthetic, analytical and projective contexts, as well as to know some applications and properties of these curves. In the synthetic approach, it was emphasized a lithe of the historical aspects, the works made by Apollonius and Dandelin, a characterization for tangent and normal lines and re ecting properties. In the analytical approach, the Cartesian, polar and parametric equations were described, as well as the applications in the Kepler Laws. In the projective approach, the concepts of projective plane, projective point, projective line and projective applications were used to give meaning to the conic in the projective universe, in addition the Theorews of Pascal and Brianchon were demonstrated. / No presente trabalho, procurou-se investigar as cônicas nos contextos sintético, analítico e projetivo, bem como conhecer algumas aplicações e propriedades dessas curvas. Na abordagem sintética, foram enfatizados um pouco do aspecto histórico, os trabalhos feitos por Apolônio e Dandelin, uma caracterização para retas tangentes e normais e as propriedades refletoras. Na abordagem analítica, foram descritas as equações cartesianas, polares e paramétricas, como também as aplicações nas Leis de Kepler. Na abordagem projetiva, foram trabalhados os conceitos de plano projetivo, ponto projetivo, reta projetiva e aplicações projetivas para dar significado as cônicas no universo projetivo, além disso foram demonstrados os teoremas de Pascal e Brianchon. / São Cristóvão, SE

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-06-30T17:23:22Z No. of bitstreams: 1 guilhermeluizdetoledocalderano.pdf: 2686756 bytes, checksum: 62a9d1a5f8ecb5cdfa552886c9c6afe2 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-13T15:58:05Z (GMT) No. of bitstreams: 1 guilhermeluizdetoledocalderano.pdf: 2686756 bytes, checksum: 62a9d1a5f8ecb5cdfa552886c9c6afe2 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-13T15:58:21Z (GMT) No. of bitstreams: 1 guilhermeluizdetoledocalderano.pdf: 2686756 bytes, checksum: 62a9d1a5f8ecb5cdfa552886c9c6afe2 (MD5) / Made available in DSpace on 2016-07-13T15:58:21Z (GMT). No. of bitstreams: 1 guilhermeluizdetoledocalderano.pdf: 2686756 bytes, checksum: 62a9d1a5f8ecb5cdfa552886c9c6afe2 (MD5) Previous issue date: 2012-12-17 / Este texto é parte de uma pesquisa acerca da Geometria Projetiva como instrumento de intervenção pedagógica no Ensino Médio. Ela se remete a estudos dentro do Mestrado Profissional em Educação Matemática da Universidade Federal de Juiz de Fora. Damos tratamento teórico e operacional aos temas mais básicos da Geometria Projetiva a partir dos teoremas de Menelau e Ceva, cujos pressupostos estão enraizados nos conceitos de colinearidade e concorrência. Sugere-se uma reflexão a partir do que se percebe no ensino de Geometria no Brasil, principalmente em torno do estudo de triângulos e do que a eles se agregam. Faz-se um resgate histórico dos teoremas mencionados e propõem-se algumas atividades norteadoras, de modo a levar o aluno (sujeito) a se defrontar com novas possibilidades de resolução de problemas. Apresenta-se um início de proposta de tratamento metodológico sobre dados de pesquisa de campo projetada. / This work is part of a research about Projective Geometry as pedagogic tool in High School. The research itself is part of studies developed during the Professional Master Degree in Mathematics and Education at Federal University of Juiz de Fora. We try to give a theoretical and operational approach to basic themes of Projective Geometry from the theorems of Menelau and Ceva, which assumptions are rooted in the concepts of collinearity and concurrency. It is suggested, then, a mature reflection of what we perceive in the teaching of Geometry in Brazil, mainly about the study of triangles and its relations. A historical survey of the theorems mentioned above is made and we propose some activities to take the student (subject) to face new possibilities to solve problems. It is presented the start of a proposal of methodological approach to data of a projective field research.

The purpose of this project was to see why projective geometry is related to the sort of sensors that machines and humans use for vision.

This thesis deals with the reconstruction of the scene using two or more images. It describes the whole reconstruction process consisting of detecting points in images, finding the appropriate geometry between images and resulting projection of these points into the space of scene. The thesis also includes a description of the application, which demonstrates the described methods.

We have two main results. Our first main result is a sharp bound for the number of vertices in a minimal forbidden subgraph for the graphs having minimum rank at most 3 over the finite field of order 2. We also list all 62 such minimal forbidden subgraphs and show that many of these are minimal forbidden subgraphs for any field. Our second main result is a structural characterization of all graphs having minimum rank at most k for any k over any finite field. This characterization leads to a very strong connection to projective geometry and we apply projective geometry results to the minimum rank problem.