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Re: Geographic Lat/Lon [message #59884]

Sat, 12 April 2008 15:45

jeffnettles4870
Messages: 111
Registered: October 2006

Senior Member

On Apr 11, 6:33 pm, robinson....@gmail.com wrote:
> On Apr 11, 5:00 pm, David Fanning <n...@dfanning.com> wrote:
>
>> David Fanning writes:
>>> lons = -130.540 * Indgen(ysize) * 4.811e-3
>>> lats = 40.00 * Indgen(xsize) * 4.811e-3
>
>> Whoops! YSIZE and XSIZE would be reversed, certainly.
>> I'm going to order another....
>
>> 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.")
>
> Thanks David. But in Geographic lons are like curve lines. Thus the
> lon value for the (1,1) pixel will be, in general, different respect
> to the (last,1) pixel.

David was correct about what these ENVI header values represent. You
can verify this yourself by opening an image in ENVI that is in the
Geographic Lat/Lon projection (i used the world_dem file that comes
with ENVI) and going to File->Edit ENVI Header. From there select
Edit Attributes and then Map Info... from that pulldown menu. Then
open the corresponding .hdr file for the image you opened in a text
editor. You can match up numbers to the values they represent that
way.

Jeff

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[Message index]

		Re: Geographic Lat/Lon By: jeffnettles4870 on Sat, 12 April 2008 15:45
		Re: Geographic Lat/Lon By: David Fanning on Fri, 11 April 2008 16:33
		Re: Geographic Lat/Lon By: robinson.inj on Fri, 11 April 2008 15:33
		Re: Geographic Lat/Lon By: David Fanning on Fri, 11 April 2008 15:00
		Re: Geographic Lat/Lon By: David Fanning on Fri, 11 April 2008 14:59
		Re: Geographic Lat/Lon By: Jean H. on Fri, 11 April 2008 14:39
		Re: Geographic Lat/Lon By: robinson.inj on Fri, 11 April 2008 14:20
		Re: Geographic Lat/Lon By: d.poreh on Fri, 11 April 2008 11:13

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