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Re: pollyfillv, area of a blob, etc... [message #59578]

Thu, 03 April 2008 07:16

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

JP writes:

> by the way, I would be happy if at least I could calculate the
> centroid of each polygon and then get the array index for each
> centroid.

I suppose the centroid of the polygon is the average
value of it vertices, or maybe the mean if you didn't
want to overbias outliers. In your case, you could
probably just pick a vertex and be pretty darn close
to it. :-)

> But I don't know how to calculate the centroid (Coyote's procedure
> CENTROID works with an array, not with a polygon).
>
> And if I had the centroid, how do I easily get the array index?

ROUND would probably work. :-)

Or, if you polygons were in some other coordinate system,
you will have to convert from that system to device coordinates.
CONVERT_COORD will be helpful.

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: pollyfillv, area of a blob, etc... By: David Fanning on Thu, 03 April 2008 07:16
		Re: pollyfillv, area of a blob, etc... By: JP on Wed, 02 April 2008 23:38
		Re: pollyfillv, area of a blob, etc... By: JP on Thu, 03 April 2008 16:08

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