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Article #1715

Re: comp geometry

#1715
From: Tim Lambert
Date: Tue, 15 Dec 1992 10:24
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>>>>> On Mon, 7 Dec 92 21:51:44 GMT, bross@splatter.nas.nasa.gov (Bill Ross) said:

> Does anyone have a formula or algorithm for calculating the biggest
> sphere that can fit in an irregular hexahedron? 

If the hexahedron is convex, then the sphere will touch four faces, so
you could test all 6_choose_4 subsets of the faces to see if the
sphere touching the four support planes is inside the hexahedron and
take the largest such sphere.

If it is not convex then you have to worry about spheres tangent to
concave vertices and edges.

> How about an n-sided  figure?

If it is convex, you could take the dual, and find the smallest
enclosing sphere by the obvious generalization of of the smalles
enclosing circle algorithm.

If not convex, then the centre of the sphere lies on Voronoi diagram
of the polyhedron, so searching that should do it, but I don't know of
a published algorithm for this...

Tim
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From: lambert@spectrum.cs.unsw.oz.au (Tim Lambert)
Subject: Re: comp geometry
In-Reply-To: bross@splatter.nas.nasa.gov's message of Mon, 7 Dec 92 21:51:44 GMT
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Date: Tue, 15 Dec 1992 10:24:35 GMT
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