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Re: GRIB data question [message #78332 is a reply to message #78331]

Thu, 10 November 2011 11:25

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

David Fanning writes:

> Yeah, OK, I agree with this. But, how do you do it? How
> do you know what coordinate system the GRIB file creator
> had in mind when he or she created the file? How do you
> know what variables you have to change to get them into
> your right-handed coordinate system?

Incidentally, I think everyone agrees on a right-hand
coordinate system (maybe some of the planetary guys do
it differently on Mars or something). That's really not
the issue.

The issue is how do you start counting columns and rows.
The map projection people use a right-handed coordinate
system. It's just that they start counting from the
upper-left corner. Positive columns go to the right,
and positive rows go down (toward the origin of their
right-handed coordinate system, if you like).

My question is this: Is there a convention for how
and where one starts to count columns and rows for
a GRIB 2D array?

Cheers,

David

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

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[Message index]

		Re: GRIB data question By: David Fanning on Fri, 11 November 2011 06:45
		Re: GRIB data question By: Kenneth P. Bowman on Fri, 11 November 2011 06:04
		Re: GRIB data question By: Kenneth P. Bowman on Fri, 11 November 2011 05:55
		Re: GRIB data question By: David Fanning on Thu, 10 November 2011 15:08
		Re: GRIB data question By: Kenneth P. Bowman on Thu, 10 November 2011 14:40
		Re: GRIB data question By: David Fanning on Thu, 10 November 2011 11:25
		Re: GRIB data question By: David Fanning on Thu, 10 November 2011 11:16
		Re: GRIB data question By: Kenneth P. Bowman on Thu, 10 November 2011 10:56
		Re: GRIB data question By: David Fanning on Thu, 10 November 2011 09:22
		Re: GRIB data question By: Fabzou on Thu, 10 November 2011 08:54

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