To the Graduate Council: I am submitting herewith a thesis written by ...
To the Graduate Council: I am submitting herewith a thesis written by ...
To the Graduate Council: I am submitting herewith a thesis written by ...
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Chapter 2: Literature Review 22Gotsman et al. describe <strong>the</strong> fund<strong>am</strong>entals of spherical par<strong>am</strong>eterization for 3D meshes[Gotsman et al., 2003]. They argue that closed manifold genus-zero meshes aretopologically equivalent to a sphere and assign a 3D position on <strong>the</strong> unit sphere toeach of <strong>the</strong> mesh vertices. They use barycentric coordinates for <strong>the</strong> planarpar<strong>am</strong>eterization. Leibowitz et al. [Leibowitz et al., 1999] share <strong>the</strong>ir memoryintensive experience in implementing geometric hashing for <strong>the</strong> comparison of proteinmolecules represented as 3D atomic structures.In [McWherter et al., 2001] model signature graphs have been proposed fortopological comparison of solid models. They extend attribute adjacency graphs,mentioned in [Joshi and Chang, 1998], to consider curved surfaces. Model signaturegraphs are constructed from boundary representation of <strong>the</strong> solid. This graph forms <strong>the</strong>shape signature of <strong>the</strong> solid model. Once a model signature graph is constructed, <strong>the</strong>solid models are compared using spectral graph <strong>the</strong>ory [Chung, 1997]. The eigenvalues of <strong>the</strong> Laplacian matrix are used in <strong>the</strong> comparison. The eigen values of <strong>the</strong>Laplacian are strongly related to o<strong>the</strong>r graph properties such as <strong>the</strong> graph di<strong>am</strong>eter.The graph di<strong>am</strong>eter is <strong>the</strong> largest number of vertices, which must be traversed, totravel from one vertex to ano<strong>the</strong>r in <strong>the</strong> graph. Ano<strong>the</strong>r technique proposed forcomparing <strong>the</strong> graphs is <strong>the</strong> use of graph invariance vectors [McWherter et al., 2001].The vectors are <strong>the</strong>n compared using L 2 norm to determine similarity between <strong>the</strong>graphs and hence <strong>the</strong> solid models. The graph invariants that form <strong>the</strong> graphinvariance vectors include node and edge count, minimum and maximum degree of<strong>the</strong> nodes, median and mode degree of <strong>the</strong> nodes, and di<strong>am</strong>eter of <strong>the</strong> graph. The useof graph invariance vectors improves <strong>the</strong> efficiency of <strong>the</strong> method. However it resultsin decrease in <strong>the</strong> accuracy of comparison. This technique has been applied tomechanical parts and is applicable to product design and manufacturing domain. Thepaper [Cardone et al., 2003] is a comprehensive survey on shape-similarity basedassessment for product design applications.Multi-Resolution Reeb Graphs presented in [Hilaga et al., 2001] have been used formodeling 3D shapes. The Reeb graph is derived from <strong>the</strong> triangle mesh models <strong>by</strong>defining a suitable function such as <strong>the</strong> geodesic curvature. The choice of <strong>the</strong> functiondepends on <strong>the</strong> topological properties selected. The range of <strong>the</strong> function over <strong>the</strong>object is split into smaller bins. The number of bins is <strong>the</strong> resolution of <strong>the</strong> Reebgraph. Each connected region in <strong>the</strong> bin will map into a node of <strong>the</strong> Reeb graph, and<strong>the</strong> adjacent nodes will be connected <strong>by</strong> edges. The Reeb graph construction has atime complexity of O (N log N), N being <strong>the</strong> number of vertices in <strong>the</strong> mesh. The Reebgraphs of two objects can be used for maximizing a similarity function atcorresponding nodes. This technique is not invariant to Euclidean transformations.We have very briefly described some of <strong>the</strong> key methods for shape analysis on 2Dintensity images and 3D mesh models. In <strong>the</strong> next section we present two tables that