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Documents authored by de Lorenzo, Stefan


Document
An Efficient, Practical Algorithm and Implementation for Computing Multiplicatively Weighted Voronoi Diagrams

Authors: Martin Held and Stefan de Lorenzo

Published in: LIPIcs, Volume 173, 28th Annual European Symposium on Algorithms (ESA 2020)


Abstract
We present a simple wavefront-like approach for computing multiplicatively weighted Voronoi diagrams of points and straight-line segments in the Euclidean plane. If the input sites may be assumed to be randomly weighted points then the use of a so-called overlay arrangement [Har-Peled & Raichel, Discrete Comput. Geom. 53:547 - 568, 2015] allows to achieve an expected runtime complexity of 𝒪(n log⁴ n), while still maintaining the simplicity of our approach. We implemented the full algorithm for weighted points as input sites, based on CGAL. The results of an experimental evaluation of our implementation suggest 𝒪(n log² n) as a practical bound on the runtime. Our algorithm can be extended to handle also additive weights in addition to multiplicative weights, and it yields a truly simple 𝒪(n log n) solution for solving the one-dimensional version of this problem.

Cite as

Martin Held and Stefan de Lorenzo. An Efficient, Practical Algorithm and Implementation for Computing Multiplicatively Weighted Voronoi Diagrams. In 28th Annual European Symposium on Algorithms (ESA 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 173, pp. 56:1-56:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{held_et_al:LIPIcs.ESA.2020.56,
  author =	{Held, Martin and de Lorenzo, Stefan},
  title =	{{An Efficient, Practical Algorithm and Implementation for Computing Multiplicatively Weighted Voronoi Diagrams}},
  booktitle =	{28th Annual European Symposium on Algorithms (ESA 2020)},
  pages =	{56:1--56:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-162-7},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{173},
  editor =	{Grandoni, Fabrizio and Herman, Grzegorz and Sanders, Peter},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2020.56},
  URN =		{urn:nbn:de:0030-drops-129224},
  doi =		{10.4230/LIPIcs.ESA.2020.56},
  annote =	{Keywords: Voronoi Diagram, multiplicative weight, additive weight, arc expansion, overlay arrangement, implementation, experiments, CGAL, exact arithmetic}
}
Document
CG Challenge
Computing Low-Cost Convex Partitions for Planar Point Sets Based on Tailored Decompositions (CG Challenge)

Authors: Günther Eder, Martin Held, Stefan de Lorenzo, and Peter Palfrader

Published in: LIPIcs, Volume 164, 36th International Symposium on Computational Geometry (SoCG 2020)


Abstract
Our work on minimum convex decompositions is based on two key components: (1) different strategies for computing initial decompositions, partly adapted to the characteristics of the input data, and (2) local optimizations for reducing the number of convex faces of a decomposition. We discuss our main heuristics and show how they helped to reduce the face count.

Cite as

Günther Eder, Martin Held, Stefan de Lorenzo, and Peter Palfrader. Computing Low-Cost Convex Partitions for Planar Point Sets Based on Tailored Decompositions (CG Challenge). In 36th International Symposium on Computational Geometry (SoCG 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 164, pp. 85:1-85:11, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{eder_et_al:LIPIcs.SoCG.2020.85,
  author =	{Eder, G\"{u}nther and Held, Martin and de Lorenzo, Stefan and Palfrader, Peter},
  title =	{{Computing Low-Cost Convex Partitions for Planar Point Sets Based on Tailored Decompositions}},
  booktitle =	{36th International Symposium on Computational Geometry (SoCG 2020)},
  pages =	{85:1--85:11},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-143-6},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{164},
  editor =	{Cabello, Sergio and Chen, Danny Z.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2020.85},
  URN =		{urn:nbn:de:0030-drops-122438},
  doi =		{10.4230/LIPIcs.SoCG.2020.85},
  annote =	{Keywords: Computational Geometry, geometric optimization, algorithm engineering, convex decomposition}
}
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