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Re: point inside polygon [message #11505 is a reply to message #11494]

Wed, 01 April 1998 00:00

Alex Schuster
Messages: 124
Registered: February 1997

Senior Member

William Connolley wrote:

> In article C0684CDB@oma.be, Philippe Peeters <philp@oma.be> writes:
>> Does anybody knows of an IDL function to test whether a given point is
>> inside a polygon?
>
> I needed to solve this recently (in a mapping context). The solution I came up
> with works but its not elegant: use poly_fill to actually draw your polygon
> (in a pixmap not the screen window if you prefer), then read off the pixel value
> of your point to see if its in or out.
>
> This is grotesquely inelegant, but its very simple and it works. I can
> post the code if you're interested. A better solution
> would be to look at polyfill and see how it does the fill... but sadly
> polyfill seems to be one of the few routines not written in IDL.

POLYFILLV works similar, but does not need a pixmap. It just returns the
subscripts of all points inside the polygon.
This worked okay for me, but for floating point coordinates it might not
be too accurate.

Alex
--
Alex Schuster Wonko@weird.cologne.de PGP Key available
alex@pet.mpin-koeln.mpg.de

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[Message index]

		Re: point inside polygon By: LC's No-Spam Newsread on Thu, 09 April 1998 00:00
		Re: point inside polygon By: manizade on Wed, 01 April 1998 00:00
		Re: point inside polygon By: wmc on Wed, 01 April 1998 00:00
		Re: point inside polygon By: Philippe Peeters on Wed, 01 April 1998 00:00
		Re: point inside polygon By: B}rd Krane on Wed, 01 April 1998 00:00
		Re: point inside polygon By: Alex Schuster on Wed, 01 April 1998 00:00
		Re: point inside polygon By: wmc on Wed, 01 April 1998 00:00

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