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I wanted a direct outline of given points on a map. I did find a divide-and-conquer algorithm, but its results are too abstract. I put in the coordinates of Texas and the convex hull of Texas looks nothing like the state.

I later realized I'm not looking for a convex hull, as I found this Convex Hull Misunderstanding?

Anyone happen to know a program that can pick out the outline points in my coordinates?

Community
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Emwat
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1 Answers1

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The polygon that forms the state of Texas is concave and not convex. Thus you need something a bit more generalized than the convex hull.

If you are dealing purely with states, there are places where you can find the coordinates that form the polygons for them, and it's likely better to use those.

Otherwise, a place to start would be research into alpha shapes.

Nuclearman
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  • Thanks. This really helped me get on the right track. Alpha shapes seem really complicated to me, so I looked more for concave. – Emwat Jul 12 '13 at 14:49