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== PM3 Quadtree ==
== PM3 Quadtree ==
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[[Image:Pm3_example.png|PM3 Quadtree example]]
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A PM3 Quadtree follows the following rules:
A PM3 Quadtree follows the following rules:
# At most, one vertex can lie in a region represented by a quadtree leaf node.
# At most, one vertex can lie in a region represented by a quadtree leaf node.
# Each region's quadtree leaf node is maximal.
# Each region's quadtree leaf node is maximal.
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[http://wam.umd.edu/~bzoller/cmsc420/pm3_example.png Here] is an example.
== Applications ==
== Applications ==
PM Quadtrees are useful in determining the region in which a point lies, the determination of the boundaries of all regions lying within a given distance of a point, and overlaying two maps.
PM Quadtrees are useful in determining the region in which a point lies, the determination of the boundaries of all regions lying within a given distance of a point, and overlaying two maps.