Planar metamorphosis by Level Set and Particle Level Set methods for tridimensional surface reconstruction

Orientador: Hélio PedriniDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: Inicialmente centralizadas na solução de problemas científicos em Dinâmica dos Fluidos, as interfaces evolutivas, com o advento da modelagem mais eficiente e robusta provida pelo método Level Set, expandiram os seus limites originais de aplicabilidade, proporcionando uma nova frente de pesquisa para os campos dos mais diversos, com destaque à Ciência da Computação. Especificamente à área de Processamento de Imagens, os trabalhos até então apresentados, relacionando o Level Set à reconstrução de superfícies tridimensionais, concentram-se na reconstrução a partir de uma nuvem de dados dispersos no espaço; a abordagem baseada em fatias planas paralelas e transversais ao objeto a ser reconstruído evidencia-se ainda incipiente. Esse cenário fomenta, portanto, uma análise da viabilidade do Level Set para a reconstrução de superfícies tridimensionais. Fundamentando-se nessa constatação, a dissertação propõe-se a oferecer uma metodologia que agregue, simultaneamente, as idéias comprovadamente eficientes já publicadas sobre a aproximação em questão e as propostas para contornar as limitações inerentes ao método ainda não satisfatoriamente tratadas, em particular a suavização excessiva de características finas dos contornos em evolução sob o Level Set. Relativamente a esse ponto, o emprego da variante Particle Level Set é sugerido como uma possível solução, por sua intrínseca capacidade comprovada para a conservação de massa ou volume de fronteiras dinâmicas traduzirem-se, presumivelmente, em um controle ao problema destacado. Ao final, conjuntos de dados sintéticos e reais são utilizados para avaliar a metodologia de reconstrução de superfícies tridimensionais apresentada qualitativamenteAbstract: Evolving interfaces were initially focused on solutions to scientific problems in Fluid Dynamics. With the advent of the more efficient and robust modeling provided by Level Set method, their original boundaries of applicability were extended, offering a new front of research to the more diverse fields, especially to Computer Science. Specifically to Image Processing area, the works published until then, relating Level Set to tridimensional surface reconstruction, centered themselves on reconstruction from a data cloud dispersed in space; the approach based on parallel planar slices transversal to the object to be reconstructed is still incipient. Therefore, this scenario foments a feasibility analysis of Level Set to the reconstruction of tridimensional surfaces. Basing on this fact, this dissertation proposes to offer a methodology that simultaneously integrates the proved efficient ideas already published about such approximation and the proposals to process the inherent limitations of the method not satisfactorily treated yet, in particular the excessive smoothing of fine characteristics of contours evolving under Level Set. In relation to this, the application of the variant Particle Level Set is suggested as a possible solution, for its intrinsic proved capability to preserve mass or volume of dynamic fronts manifests itself, presumably, into a control of the stressed problem. At the end, synthetic and real data sets are used to evaluate the presented tridimensional surface reconstruction methodology qualitativelyMestradoCiência da ComputaçãoMestre em Ciência da Computaçã

Interaktive Echtzeitsimulation deformierbarer Oberflächen für Trainingssysteme in der Augenchirurgie

Die Arbeit befasst sich mit Simulations-Algorithmen für virtuelle Augenoperationen. Sie konzentriert sich auf die Simulation von Membranen, die im Verlauf eines chirurgischen Eingriffs aus dem Auge entfernt werden müssen. Es werden Algorithmen vorgestellt, die eine realistische Interaktion zwischen Membran und chirurgischem Instrument ermöglichen, und die eine physikalisch plausible Riss-Simulation garantieren

Interactive freeform editing techniques for large-scale, multiresolution level set models

Level set methods provide a volumetric implicit surface representation with automatic smooth blending properties and no self-intersections. They can handle arbitrary topology changes easily, and the volumetric implicit representation does not require the surface to be re-adjusted after extreme deformations. Even though they have found some use in movie productions and some medical applications, level set models are not highly utilized in either special effects industry or medical science. Lack of interactive modeling tools makes working with level set models difficult for people in these application areas.This dissertation describes techniques and algorithms for interactive freeform editing of large-scale, multiresolution level set models. Algorithms are developed to map intuitive user interactions into level set speed functions producing specific, desired surface movements. Data structures for efficient representation of very high resolution volume datasets and associated algorithms for rapid access and processing of the information within the data structures are explained. A hierarchical, multiresolution representation of level set models that allows for rapid decomposition and reconstruction of the complete full-resolution model is created for an editing framework that allows level-of-detail editing. We have developed a framework that identifies surface details prior to editing and introduces them back afterwards. Combining these two features provides a detail-preserving level set editing capability that may be used for multi-resolution modeling and texture transfer. Given the complex data structures that are required to represent large-scale, multiresolution level set models and the compute-intensive numerical methods to evaluate them, optimization techniques and algorithms have been developed to evaluate and display the dynamic isosurface embedded in the volumetric data.Ph.D., Computer Science -- Drexel University, 201