Re: [R] [ESRI-L] outline polygons of point clumps

From: Xiaohua Dai <>
Date: Sat 13 May 2006 - 02:48:02 EST

Sorry, I did not make my question clear. Since I have a point theme with many points, some of them may clump together. the problems here are:
1. how to find clumps in a point theme? 2. the convex-hull extension I found only deal with all the points in a theme at each time? how to make each convex hull around each point clump automatically?



On 5/12/06, Bob Booth <> wrote:
> Xiaohua,
> That would be one way to do it. There are others.
> Try searching ArcScripts for "convex hull"
> For example:
> or
> Bob
> -----Original Message-----
> From: ESRI-L [] On Behalf Of Xiaohua Dai
> Sent: Friday, May 12, 2006 2:33 AM
> To:
> Subject: [ESRI-L] outline polygons of point clumps
> Dear all,
> How to generate one outline polygon for each point clump? Are there
> any present functions in ArcView, ArcGIS, R or some freewares? I just
> had a quick look at the package adehabitat and did not find the
> function.
> To my knowledge, I could do it as follows: 1) make a grid map of my
> study area with cell values = 0; 2) assign 1 to the cells containing
> at least one point; 3) convert the 1-value cells into polygons.
> Am I right?
> Thanks
> Xiaohua

Xiaohua Dai, Dr.
* Postdoctoral in elephant-tree ecosystem simulation
Centre for Systems Research, Durban Institute of Technology
P.O.Box 953, Durban 4000, South Africa
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Received on Sat May 13 02:57:48 2006

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