Python - Convex Hull with Some Permissible Interior Points?

Concave hull might be what you're looking for, though it doesn't use an angle as far as I know. The algorithm that the LOCAL project uses seems to use k nearest neighbours.

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I'd like to make a convex hull of a set of 2D points (in python). I've found several examples which have helped, but I have an extra feature I'd like that I haven't been able to implement. What I want to do is create the convex hull but allow it to pick up interior points if they are sufficiently "close" to the boundary.

See the picture below -> if theta Speed is not really a concern here as the number of points I'll be working with will be relatively small. I'd rather have a more robust algorithm then a quick one. I'm wondering if anyone knows of any such example or could point me in the right direction of where to start.

Thanks. Python algorithm geometry convex-hull link|improve this question edited Apr 6 '11 at 2:05Tom Zych3,922617 asked Apr 6 '11 at 1:35Scott B360210 100% accept rate.

It's a relatively simple problem to bruteforce your way through if you can re-iterate all non-hull points to check against neighborhood. You could get out of it easily, but it's several orders more computationally intensive than what you have. – ThE_JacO Apr 6 '11 at 1:39 When calculating the next point in the hull, rotate the line you're checking by x degrees, and add every point that succeeds recursively?

– bdares Apr 6 '11 at 1:43 @ThE_JacO: The total number of points wouldn't exceed more then a few hundred points. – Scott B Apr 6 '11 at 20:27.

It looks like alpha shapes is probably about what I'm looking for. Thanks. – Scott B Apr 6 '11 at 20:25.

You could first compute the convex hull, and then ruin round the edges of that seeing if any of the edges should be broken to include an interior point.

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