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Re: intersecting polygons [message #29386 is a reply to message #29374]

Mon, 18 February 2002 04:03

jvp10
Messages: 4
Registered: February 2002

Junior Member

David,

It's elegant enough! Many thanks.

Jon Pearce.

David Fanning <david@dfanning.com> wrote in message news:<MPG.16da08ed83e1ed8a98980b@news.frii.com>...
> Jonathan Pearce (jvp10@psu.edu) writes:
>
>> Does anybody know of, or have a routine that could take polygonal
>> areas and find the common area between them? Consider the first
>> polygon defined by the set of points x1,y1 where x1 and y1 are arrays.
>> The second polygon is defined by the set of points x2 and y2. What I
>> am looking for is the points where the lines given by x1,y1 and x2,y2
>> intersect. Owing to limited time I am wondering if anybody has written
>> such a routine, that would return a polygon describing the area common
>> to both polygons.
>
> This probably falls under the category of the world's
> biggest hack, but I've used it to good effect.
>
> I use POLYFILLV with the two polygons to get a list
> of indices (or pixels) that belong to the two polygons.
> I then find the intersection of the two sets of pixels
> with the SetIntersection program (modified with some
> error checking in my real-world program), that you can
> find here:
>
> http://www.dfanning.com/tips/set_operations.html
>
> Knowing the pixel "size" allows me to calculate
> areas, etc. You can probably use IDLanROI for the
> same purpose. It's worked for me, although I don't
> make any claims as to its elegance. :-)
>
> Cheers,
>
> David

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[Message index]

		Re: intersecting polygons By: meron on Mon, 18 February 2002 15:45
		Re: intersecting polygons By: Pavel A. Romashkin on Mon, 18 February 2002 14:40
		Re: intersecting polygons By: jvp10 on Mon, 18 February 2002 04:03
		Re: intersecting polygons By: David Fanning on Sun, 17 February 2002 17:38

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