inria-00072646, version 1
An Elementary Algorithm for Reporting Intersections of Red/Blue Curve Segments
Jean-Daniel Boissonnat
1Antoine Vigneron 1
N° RR-3999 (2000)
Résumé : Let E_r and E_b be two sets of x-monotone and non-intersecting curve segments, E=E_r \cup E_b and |E|=n. We give a new sweep-line algorithm that reports the $k$ intersecting pairs of segments of E. Our algorithm uses only three simple predicates that allow to decide if two segments intersect, if a point is left or right to another point, and if a point is above, below or on a segment. These three predicates seem to be the simplest predicates that lead to subquadratic algorithms. Our algorithm is almost optimal in this restricted model of computation. Its time complexity is $O((n+k)\logn) and it requires O(n) space. The same algoritm has been described in our previous report [5]. That report presented also an algoritm for the general case but its analysis was not not correct.
- 1 : PRISME (INRIA Sophia Antipolis)
- INRIA
- Domaine : Informatique/Autre
- Mots-clés : COMPUTATIONAL GEOMETRY – ROBUSTNESS – EXACT ARITHMETIC – SWEEP-LINE ALGORITHMS
- Référence interne : RR-3999
- inria-00072646, version 1
- http://hal.inria.fr/inria-00072646
- oai:hal.inria.fr:inria-00072646
- Contributeur : Rapport De Recherche Inria
- Soumis le : Mercredi 24 Mai 2006, 10:29:31
- Dernière modification le : Jeudi 6 Novembre 2008, 14:43:46






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