PhD Thesis 14625
Institute of Computer Systems
Keywords: Geometric modeling, non-manifolds, boundary representation, multiresolution representation, subdivision surfaces, model fairing, model editing, surface feature extraction, surface morphing
This thesis introduces a novel geometric modeling environment to represent and interact with non-manifold models. This functionality is required in many application domains, where the complexity of models has been steadily increasing as a result of the improved acquisition systems. This project focuses on the domain of geoscience, a choice motivated by the cooperation between the Federal Institute of Technology (ETH) in Zurich, the Schlumberger Austin Technology Center (ATC) and the Schlumberger Cambridge Research (SCR) center. The tools designed in this project are based on an extended boundary representation data structure, which accommodates semantics information in addition to geometric and topological data. In particular, the separation of the topological description of a simplicial complex from its embedding information and the definition of different types of embeddings results in a flexible description of models. The core component of the system is a non-manifold fairing tool that attenuates the high frequencies present in models; the smoothing process is defined as an extension of the corresponding operators for manifold surfaces. The problem of the change in the volumes present in a non-manifold, which is caused by the application of this operator, has been addressed by constructing a novel local volume preservation technique. The second component of the framework is a non-manifold subdivision tool, which iteratively refines and smooths an initially coarse model. This operation is constructed either by extending the classic Loop scheme or by defining a new subdivision operator based on the fairing tool. The interaction with the system is enhanced by the simplification tool, which is responsible for the construction of a multiresolution representation of both height field data and non-manifolds. The principal applications of these structures comprise the generalization of other tools to a multiresolution setting and the construction of approximations for rendering and further data processing. The fairing and simplification components are combined to define a multiresolution editing tool for non-manifold models. In contrast to other techniques this component operates directly on the model and it does not rely on the extraction and subsequent processing of manifold surfaces. The construction of a feature detection tool for triangulated two-manifold surfaces automates the extraction of the salient characteristics of a surface, which are defined as coherent regions of high curvature. This data is applied both to the analysis and interpretation of models and to guide the fairing, subdivision and simplification tools. A novel approach to mesh morphing is introduced, which computes the paths of each mesh vertex in the deformation process as the result of a Laplace equation. This elegant formulation offers a variety of advantages, such as the capability of specifying constraints that are smoothly integrated into the problem formulation. These operators have been integrated into a modeling framework and they have been combined to implement data processing pipelines to construct and interact with models. Their strengths and limitations will be analyzed on a variety of geological and graphics models.
Diese Website wird in älteren Versionen von Netscape ohne graphische Elemente dargestellt. Die Funktionalität der Website ist aber trotzdem gewährleistet. Wenn Sie diese Website regelmässig benutzen, empfehlen wir Ihnen, auf Ihrem Computer einen aktuellen Browser zu installieren. Weitere Informationen finden Sie auf
The content in this site is accessible to any browser or Internet device, however, some graphics will display correctly only in the newer versions of Netscape. To get the most out of our site we suggest you upgrade to a newer browser.