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Re: AVHRR Image Mapping Problem [message #51991 is a reply to message #51847]

Fri, 15 December 2006 10:23

James Kuyper
Messages: 425
Registered: March 2000

Senior Member

David Fanning wrote:
> kuyper@wizard.net writes:
>
>> One thing you could check is the possibility that the standard
>> parallels are reversed: does it work better if you use -21 and +19?
>
> Humm. Well, now the upper part of the map is correct, but
> the error is transferred to the lower part of the map.
> (I just multiplied the standard parallels by minus 1.)
> Does this give you any clues?

Actually, yes. I have no idea why the standard parrallels might be
incorrect, but given the symptoms you describe, it might be worthwile
to try 19.99999 and -20.00001. IDL doesn't like it when the standard
parallels add up to exactly zero. That is unfortunate, because a Albers
projection with standard parallels adding up to zero is a different way
of describing the cylindrical equal-area projection, one of my favorite
map projections, and one that IDL doesn't support.

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[Message index]

		Re: AVHRR Image Mapping Problem By: David Fanning on Fri, 15 December 2006 10:17
		Re: AVHRR Image Mapping Problem By: David Fanning on Fri, 15 December 2006 10:13
		Re: AVHRR Image Mapping Problem By: Jean H. on Fri, 15 December 2006 09:39
		Re: AVHRR Image Mapping Problem By: Braedley on Fri, 15 December 2006 09:44
		Re: AVHRR Image Mapping Problem By: Matt[1] on Fri, 15 December 2006 09:37
		Re: AVHRR Image Mapping Problem By: David Fanning on Fri, 15 December 2006 09:29
		Re: AVHRR Image Mapping Problem By: James Kuyper on Fri, 15 December 2006 09:21
		Re: AVHRR Image Mapping Problem By: Paul Van Delst[1] on Fri, 15 December 2006 08:11
		Re: AVHRR Image Mapping Problem By: David Fanning on Fri, 15 December 2006 08:10
		Re: AVHRR Image Mapping Problem By: David Fanning on Fri, 15 December 2006 07:55
		Re: AVHRR Image Mapping Problem By: James Kuyper on Fri, 15 December 2006 10:23

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