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Re: map_continents and /fill... revisted [message #76798 is a reply to message #76794]

Wed, 29 June 2011 20:11

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Michael Galloy writes:

> Do you have IDL 8.1? I don't use maps in IDL personally, but the release
> notes for IDL 8.1 says it improved the quality of the continental and
> country outlines.

IDL 8.1 does indeed allow the use of the GSHHS database,
which is generally thought to be one of the best in the
world for this kind of thing.

Unfortunately, the GSHHS software comes in several
"resolutions". IDL has included only the very highest
resolution, which you might think would be a good idea,
and probably is if your interest is in a rocky island
somewhere off the cost of Peru. If your interest is in
processing a map of the world, or even a reasonably
large portion of the world, then using the highest
resolution GSHHS is overkill in the extreme and will
result in VERY long rendering times. (And I mean long
even in terms of the normal function graphics rendering
times.)

It seems to me it still makes more sense to download
the GSHHS database yourself, and then use the resolution
that makes sense for your application. Coyote Library
routines are available to work with this database in
exactly the same way Map_Continents works with the
old IDL database.

http://www.idlcoyote.com/map_tips/gshhs.html

Cheers,

David

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

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[Message index]

		Re: map_continents and /fill... revisted By: TonyL on Sun, 03 July 2011 22:12
		Re: map_continents and /fill... revisted By: Brian McNoldy on Fri, 01 July 2011 11:57
		Re: map_continents and /fill... revisted By: Fabzou on Thu, 30 June 2011 01:48
		Re: map_continents and /fill... revisted By: David Fanning on Wed, 29 June 2011 20:11
		Re: map_continents and /fill... revisted By: Michael Galloy on Wed, 29 June 2011 14:09

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