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Re: area enclosed by a poylgon on a sphere [message #16545 is a reply to message #16542]

Tue, 03 August 1999 00:00

Nick Bower
Messages: 43
Registered: June 1999

Member

> I need to be able to find the area enclosed by an arbitrarily shaped
> series of lat/lon points on the surface of the Earth. I have been told
> that I can solve this using Green's Theorem, but before I gut through
> the math I was hoping that someone would have solved this and be willing
> to share the code. If it is already in IDL that would be great, but any
> language will do.

What does area in lat's and lon's mean? Since there is no unique
"square lat/lon" area unit, you'd have to use a projection at some point
I would guess. Don't have any code then for the area - always used
ArcView for this type of thing. But maybe it's possible to project,
pick a point inside a *convex* polygon, connect it with each vertex and
find the summed area of triangles. You'd end up with an area, but it's
specific to your spheroid/projection pair. Sorry if it's not what
you're after, as there's a real chance you won't have a convex shape.

nick

--

Nick Bower
Space Science and Engineering Center
University of Wisconsin - Madison
http://arm1.ssec.wisc.edu/~nickb

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[Message index]

		Re: area enclosed by a poylgon on a sphere By: Struan Gray on Wed, 04 August 1999 00:00
		Re: area enclosed by a poylgon on a sphere By: Struan Gray on Tue, 03 August 1999 00:00
		Re: area enclosed by a poylgon on a sphere By: Craig Markwardt on Tue, 03 August 1999 00:00
		Re: area enclosed by a poylgon on a sphere By: Nick Bower on Tue, 03 August 1999 00:00

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