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

From: Xiaohua Dai <ecoinformatics_at_gmail.com>
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?

Thanks.

Xiaohua

On 5/12/06, Bob Booth <bbooth@esri.com> wrote:
> Xiaohua,
>
> That would be one way to do it. There are others.
> Try searching ArcScripts for "convex hull"
>
http://arcscripts.esri.com/
>
> For example:
> http://arcscripts.esri.com/details.asp?dbid=14535
> or
> http://arcscripts.esri.com/details.asp?dbid=12084
>
> Bob
>
>
> -----Original Message-----
> From: ESRI-L [mailto:ESRI-L@esri.com] On Behalf Of Xiaohua Dai
> Sent: Friday, May 12, 2006 2:33 AM
> To: ESRI-L@esri.com
> 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
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Centre for Systems Research, Durban Institute of Technology
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Received on Sat May 13 02:57:48 2006

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