On the Reduction of the Spherical Point-in-Polygon Problem for Antipode-Excluding Spherical Polygons

Fuente: arXiv
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Autores principales: Li, Ziqiang, Sun, Jindi
Formato: Preprint
Publicado: 2023
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author Li, Ziqiang
Sun, Jindi
author_facet Li, Ziqiang
Sun, Jindi
contents Spherical polygons used in practice are nice, but the spherical point-in-polygon problem (SPiP) has long eluded solutions based on the winding number (wn). That a punctured sphere is simply connected is to blame. As a workaround, we prove that requiring the boundary of a spherical polygon to never intersect its antipode is sufficient to reduce its SPiP problem to the planar, point-in-polygon (PiP) problem, whose state-of-the-art solution uses wn and does not utilize known interior points (KIP). We refer to such spherical polygons as boundary antipode-excluding (BAE) and show that all spherical polygons fully contained within an open hemisphere is BAE. We document two successful reduction methods, one based on rotation and the other on shearing, and address a common concern. Both reduction algorithms, when combined with a wn-PiP algorithm, solve SPiP correctly and efficiently for BAE spherical polygons. The MATLAB code provided demonstrates scenarios that are problematic for previous work.
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publishDate 2023
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spellingShingle On the Reduction of the Spherical Point-in-Polygon Problem for Antipode-Excluding Spherical Polygons
Li, Ziqiang
Sun, Jindi
Computational Geometry
General Topology
Spherical polygons used in practice are nice, but the spherical point-in-polygon problem (SPiP) has long eluded solutions based on the winding number (wn). That a punctured sphere is simply connected is to blame. As a workaround, we prove that requiring the boundary of a spherical polygon to never intersect its antipode is sufficient to reduce its SPiP problem to the planar, point-in-polygon (PiP) problem, whose state-of-the-art solution uses wn and does not utilize known interior points (KIP). We refer to such spherical polygons as boundary antipode-excluding (BAE) and show that all spherical polygons fully contained within an open hemisphere is BAE. We document two successful reduction methods, one based on rotation and the other on shearing, and address a common concern. Both reduction algorithms, when combined with a wn-PiP algorithm, solve SPiP correctly and efficiently for BAE spherical polygons. The MATLAB code provided demonstrates scenarios that are problematic for previous work.
title On the Reduction of the Spherical Point-in-Polygon Problem for Antipode-Excluding Spherical Polygons
topic Computational Geometry
General Topology
url https://arxiv.org/abs/2309.03822