Abstract
A simple polygon P is LR-visible if there are two points s, t on the boundary of P such that every point on the clockwise boundary of P from s to t is visible from some point of the other boundary of P from t to s and visa versa. In this paper, we give a simple, explict characterization of LR-visibility polygons. It is obtained by mapping the structure of non-redundant components used in determining LR-visibility into a set of directed chords of a circle. Using our characterization, we further develop a simple O(n) time algorithm for determining whether a given polygon is LR-visible. This greatly simplifies the existing algorithms for determining whether a simple polygon is LR-visible and for reporting all pairs s and t which admit LR-visibility as well.
Work by Tan was partially supported by Grant-in-Aid (23500024) for Scientific Research from Ministry of Education, Science and Culture, Japan, and Japan Society for the Promotion of Science.
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© 2011 Springer-Verlag Berlin Heidelberg
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Tan, X., Zhang, J., Jiang, B. (2011). Simple Characterization of LR-visibility Polygons. In: Akiyama, J., Bo, J., Kano, M., Tan, X. (eds) Computational Geometry, Graphs and Applications. CGGA 2010. Lecture Notes in Computer Science, vol 7033. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-24983-9_18
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DOI: https://doi.org/10.1007/978-3-642-24983-9_18
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