[postgis-users] convex hull

[Howard Butler]

On Jun 22, 2010, at 10:09 AM, Stephen Crawford wrote:

> All,
> 
> I'm trying to get the polygon outline of a collection of points.  I used ConvexHull, and what I got was--hence the name--convex.  Is there a way to get a more exact outline?  In my image below, the points are in purple and the convex hull is in red.  I want to get a poly that more closely matches the points.
> 
> Thanks,
> Steve
> 
> <moz-screenshot.png>

You want a concave hull

http://ubicomp.algoritmi.uminho.pt/local/concavehull.html

Howard