License: Creative Commons Attribution 3.0 Unported license (CC BY 3.0)
When quoting this document, please refer to the following
DOI: 10.4230/LIPIcs.SoCG.2018.61
URN: urn:nbn:de:0030-drops-87749
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Milenkovic, Victor ; Sacks, Elisha ; Butt, Nabeel

Table Based Detection of Degenerate Predicates in Free Space Construction

LIPIcs-SoCG-2018-61.pdf (4 MB)


The key to a robust and efficient implementation of a computational geometry algorithm is an efficient algorithm for detecting degenerate predicates. We study degeneracy detection in constructing the free space of a polyhedron that rotates around a fixed axis and translates freely relative to another polyhedron. The structure of the free space is determined by the signs of univariate polynomials, called angle polynomials, whose coefficients are polynomials in the coordinates of the vertices of the polyhedra. Every predicate is expressible as the sign of an angle polynomial f evaluated at a zero t of an angle polynomial g. A predicate is degenerate (the sign is zero) when t is a zero of a common factor of f and g. We present an efficient degeneracy detection algorithm based on a one-time factoring of every possible angle polynomial. Our algorithm is 3500 times faster than the standard algorithm based on greatest common divisor computation. It reduces the share of degeneracy detection in our free space computations from 90% to 0.5% of the running time.

BibTeX - Entry

  author =	{Victor Milenkovic and Elisha Sacks and Nabeel Butt},
  title =	{{Table Based Detection of Degenerate Predicates in Free Space Construction}},
  booktitle =	{34th International Symposium on Computational Geometry (SoCG 2018)},
  pages =	{61:1--61:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-066-8},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{99},
  editor =	{Bettina Speckmann and Csaba D. T{\'o}th},
  publisher =	{Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{},
  URN =		{urn:nbn:de:0030-drops-87749},
  doi =		{10.4230/LIPIcs.SoCG.2018.61},
  annote =	{Keywords: free space construction, degenerate predicates, robustness}

Keywords: free space construction, degenerate predicates, robustness
Collection: 34th International Symposium on Computational Geometry (SoCG 2018)
Issue Date: 2018
Date of publication: 08.06.2018

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