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Re: Understanding IDLanROI [message #73156 is a reply to message #73088]

Mon, 25 October 2010 09:17

Matt[2]
Messages: 69
Registered: March 2007

Member

On Oct 22, 8:16 am, kBob <krd...@gmail.com> wrote:

> To find the polygons that are holes, I use the IDL routine POLY_AREA.
> The /SIGNED keyword returns the area as either positive or negative,
> which tells you if the vertices are counterclockwise or clockwise. All
> the State polygons from states.shp are clockwise.
>

Kelly,

Thanks so much for this tip. It has saved me. So other people out
there. Is this the preferred method to determine the vertex's
direction? internal vs external?

This is more out of interest than need. The poly_area is working like
a charm for me.

Thanks,
Matt

--
Matthew Savoie - Manager of Science Programmers
National Snow and Ice Data Center
(303) 735-0785 http://nsidc.org

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[Message index]

		Understanding IDLanROI By: KRDean on Fri, 08 October 2010 14:13
		Re: Understanding IDLanROI By: KRDean on Tue, 19 October 2010 08:02
		Re: Understanding IDLanROI By: David Fanning on Tue, 19 October 2010 10:38
		Re: Understanding IDLanROI By: guillermo.castilla.ca on Wed, 20 October 2010 10:01
		Re: Understanding IDLanROI By: KRDean on Fri, 22 October 2010 07:16
		Re: Understanding IDLanROI By: Matt[2] on Mon, 25 October 2010 09:17
		Re: Understanding IDLanROI By: guillermo.castilla.ca on Wed, 27 October 2010 08:44
		Re: Understanding IDLanROI By: guillermo.castilla.ca on Mon, 01 November 2010 06:23
		Re: Understanding IDLanROI By: guillermo.castilla.ca on Mon, 01 November 2010 06:24
		Re: Understanding IDLanROI By: David Fanning on Tue, 19 October 2010 14:02
		Re: Understanding IDLanROI By: KRDean on Tue, 19 October 2010 13:19

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