A Laplace Operator on Semi-Discrete Surfaces
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This paper studies a Laplace operator on semi-discrete surfaces. A semi-discrete surface is represented by a mapping into three-dimensional Euclidean space possessing one discrete variable and one continuous variable. It can be seen as a limit case of a quadrilateral mesh, or as a semi-discretization of a smooth surface. Laplace operators on both smooth and discrete surfaces have been an object of interest for a long time, also from the viewpoint of applications. There are a wealth of geometric objects available immediately once a Laplacian is defined, e.g., the mean curvature normal. We define our semi-discrete Laplace operator to be the limit of a discrete Laplacian on a quadrilateral mesh, which converges to the semi-discrete surface. The main result of this paper is that this limit exists under very mild regularity assumptions. Moreover, we show that the semi-discrete Laplace operator inherits several important properties from its discrete counterpart, like symmetry, positive semi-definiteness, and linear precision. We also prove consistency of the semi-discrete Laplacian, meaning that it converges pointwise to the Laplace–Beltrami operator, when the semi-discrete surface converges to a smooth one. This result particularly implies consistency of the corresponding discrete scheme.
KeywordsLaplace operator Semi-discrete surfaces Quadrilateral meshes Consistency
Mathematics Subject ClassificationPrimary 53B20 Secondary 53A05 41A25
The author would like to thank J. Wallner for fruitful discussions and comments. This research was supported by the DFG-Collaborative Research Center, TRR 109, “Discretization in Geometry and Dynamics” and the Doctoral Program “Discrete Mathematics” through grants I 706-N26 and W1230 of the Austrian Science Fund (FWF). We further acknowledge support from NAWI Graz and are grateful to the anonymous reviewers for their remarks and suggestions.
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