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Title: Visualisation of irregular, finite element data
Author: Simpson, T.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 1999
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This thesis outlines work into the development of efficient techniques for visualisation of datasets generated using finite element analyses. In particular, the work concentrates on datasets that require quadratic interpolation methods to accurately visualise simulation results. Typically for example, this includes simulations into non-Newtonian fluids where the use of quadratic shape functions is necessary to obtain acceptable results. Our first concern is fundamental algorithms for analysing irregular domains, typically constructed from triangular or tetrahedral cells. This includes methods for reducing the search space through domain space decomposition (octrees) and point location tests for interpolation. To this end, a new octree method is introduced, termed the “extended-nodes” octree which is shown to be a space-efficient data structure for irregular grids. The work continues to describe how commonly used visualisation techniques such as surface tiling and volume rendering can be adapted to work with quadratic interpolation functions over irregular grids. Particular interest is given to image quality and algorithm efficiency. In the context of volume rendering, a staged interpolation function is described based on a standard method found in the literature. This is shown to be substantially quicker whilst giving visually identical results. For surface tiling, a new recursive, adaptive algorithm is described which solves many of the problems encountered when tiling higher-order surfaces. The work on surface visualisation culminates in the introduction of a new algorithm termed Irregular, Quadratic, Direct Surface Rendering (IQDSR). This ray-casting method is shown to produce high-quality images of quadratic iso-surfaces within finite element data in a highly efficient manner. Finally, consideration is given to the visualisation of fluid flow (vector) data, common within finite element analysis. In particular, a review of both volume rendering based methods is given, along with a more in-depth discussion into particle based methodologies. Altogether, this work gives both a review of current linear finite element scalar and vector visualisation algorithms, and outlines new techniques which extend these methods to utilise quadratic interpolation functions over irregular meshes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available