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Re: Map Projections [message #69371 is a reply to message #27969]

Fri, 15 January 2010 12:52

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Bennett writes:

> I currently have data with an associated latitude and longitude
> frame. I've seen David Fanning's "Navigating GOES Images" example but
> the process does not seem to work for my data.
> When I say it does not work the resulting projection results in
> showing much less of the data than it should based on the lat/lon
> limits.

How are you choosing the "limits"? These are not necessarily
the corners of your image.

> Does the data inherently have to be North up and east/west going right/
> left? My data is presented in an orientation where North is at an
> angle as are the other directions where the bottom of the image is not
> lowest latitude etc... Is there a special way to handle the
> projection for these types of datasets?

No, pick the upper-left corner of the rectangular image as your
starting point, and you should be good to go. What kind of map
projection is this, what is the lat/lon in the upper left corner,
what size is your image in pixels, and what is the resolution of
a pixel in meters? (You *can* determine the later number from
the lat/lon corners of your image.)

> The end result I'm looking for is a GeoTiff. I would think that with
> all this information at my fingertips IDL would make this easy but
> alas it is not.

You have been reading WAY too many marketing materials. :-)

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]

		Map projections By: James Kuyper on Mon, 12 November 2001 07:55
		Re: map projections By: jeffnettles4870 on Wed, 13 February 2008 14:04
		Re: Map Projections By: David Fanning on Fri, 15 January 2010 13:12
		Re: Map Projections By: Juggernaut on Mon, 18 January 2010 05:16
		Re: Map Projections By: David Fanning on Fri, 15 January 2010 12:52
		Re: Map Projections By: Juggernaut on Mon, 18 January 2010 09:28
		Re: Map Projections By: Juggernaut on Mon, 18 January 2010 11:00
		Re: Map Projections By: David Fanning on Mon, 18 January 2010 09:41

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