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Re: contour over a map and 180 degrees off or problems with dateline [message #53820 is a reply to message #53740]

Wed, 02 May 2007 12:48

teich
Messages: 33
Registered: May 2007

Member

David, these sort of thing confuse me too!

I wonder if it's possible that contour and map_set could be made more
user friendly one day?

Thanks again,

Howie

On May 2, 3:32 pm, David Fanning <n...@dfanning.com> wrote:
> t...@atmsci.msrc.sunysb.edu writes:
>> If I keep the lon array as is (i.e., -177.5, ..., +177.5) and use your
>> field=Shift(field,36,0) then everything looks in the right location
>> and there is no problem at the dateline. Although this fixed the
>> problem, what if I had an odd number of elements for array lon? Since
>> I compare plots visually, it may be important to get the exact
>> locations. Would you suggest this type of fix (using Shift) for every
>> contour of this type?
>
> Well, I don't know. These kinds of things always confuse me. :-)
>
> It seems to me one of two things has to be wrong. (1) Your
> longitude vector does really describe the physical locations
> of your data (I.e., the left edge of your array is not
> at -177.5 degrees of longitude), or (2) the map projection
> is not centered with respect to the data (I.e., the center of
> the data and the center of the map are at two different places).
>
> I think if you resolve this problem, then shifting, which I would
> only use as a last resort, would probably go away.
>
> Cheers,
>
> David
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming:http://www.dfanning.com/
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		contour over a map and 180 degrees off or problems with dateline By: teich on Wed, 02 May 2007 10:51
		Re: contour over a map and 180 degrees off or problems with dateline By: David Fanning on Wed, 02 May 2007 12:51
		Re: contour over a map and 180 degrees off or problems with dateline By: teich on Wed, 02 May 2007 12:48
		Re: contour over a map and 180 degrees off or problems with dateline By: David Fanning on Wed, 02 May 2007 12:32
		Re: contour over a map and 180 degrees off or problems with dateline By: teich on Wed, 02 May 2007 12:20
		Re: contour over a map and 180 degrees off or problems with dateline By: David Fanning on Wed, 02 May 2007 11:52
		Re: contour over a map and 180 degrees off or problems with dateline By: teich on Wed, 02 May 2007 11:41
		Re: contour over a map and 180 degrees off or problems with dateline By: David Fanning on Wed, 02 May 2007 11:07

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