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Re: GeoTiff- grid [message #58305 is a reply to message #58167]

Thu, 24 January 2008 06:29

robinson.inj
Messages: 32
Registered: August 2007

Member

On Jan 24, 7:40 am, David Fanning <n...@dfanning.com> wrote:
> robinson....@gmail.com writes:
>> well, my 0.00000000001% was:
>> mrcMap=3Dmap_projetion_init('Mercator', DATUM=3D8, /GCTP, $
>> SEMIMAJOR_AXIS=3D0, SEMIMINOR_AXIS=3D0, $; porbably datum 8 deals
>> with this
>> CENTER_LONGITUDE=3D-96.5, TRUE_SCALE_LATITUDE=3D20, $
>> FALSE_EASTING=3D0, FALSE_NORTHING=3D0)
>
> Well, now. I think this is a *little* more important than
> that!
>
> Of course, I ran into the same problem. There are two
> "Mercator" projections available in IDL, and they take
> different keywords. Moreover, they give you results that
> differ by 20+ degrees of latitude. Aren't you just the
> least little bit curious about that? I know I am. :-)
>
> Plus, the one that apparently "works" is the one I can't
> get to work from my knowledge of what is in the GeoTiff
> file. It seems specialized knowledge has been called into
> play here. I'd like to know how I was suppose to discover
> that. Anyone have any ideas?
>
> 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.")

Absolutly. I am very curious about that. but after 2 days trying to
undertsand the big difference I am just going to use the GCTP keyword
if I were in a boat :-).
I think that in IDL mercator the center_LATITUDE must be located into
the image. However I can dicide to cut the image if it were too big. I
took a short latitude range from a big image (by preserving the same
longitude range). Probably USGS mercator (GCTP) have already thought
about this possibility. It is just a idea.

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[Message index]

		GeoTiff- grid By: robinson.inj on Mon, 21 January 2008 13:59
		Re: GeoTiff- grid By: David Fanning on Wed, 23 January 2008 11:00
		Re: GeoTiff- grid By: robinson.inj on Wed, 23 January 2008 23:35
		Re: GeoTiff- grid By: robinson.inj on Wed, 23 January 2008 10:52
		Re: GeoTiff- grid By: David Fanning on Wed, 23 January 2008 07:49
		Re: GeoTiff- grid By: David Fanning on Wed, 23 January 2008 07:29
		Re: GeoTiff- grid By: robinson.inj on Wed, 23 January 2008 07:15
		Re: GeoTiff- grid By: robinson.inj on Wed, 23 January 2008 05:08
		Re: GeoTiff- grid By: David Fanning on Tue, 22 January 2008 15:31
		Re: GeoTiff- grid By: David Fanning on Tue, 22 January 2008 15:17
		Re: GeoTiff- grid By: robinson.inj on Tue, 22 January 2008 15:01
		Re: GeoTiff- grid By: David Fanning on Thu, 24 January 2008 06:48
		Re: GeoTiff- grid By: robinson.inj on Thu, 24 January 2008 06:29
		Re: GeoTiff- grid By: David Fanning on Thu, 24 January 2008 05:40

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