| Re: Returning Land Type [message #51800] |
Fri, 08 December 2006 07:34 |
KRDean
Messages: 69
Registered: July 2006
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Member |
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I did this a few years ago with the 1km Global Land Cover
Characteristics
Database from USGS (usgs2_0g.img.gz). There are several different
land, vegetation, and water values provided as a byte value. The data
file and legend can be found at...
http://edcdaac.usgs.gov/glcc/globdoc2_0.html
It is easy to compute the navigation so you can extract the value --
lin = ( 89.99583333333334 - lat ) / 0.00833333333333
ele = ( -179.99583333333334 - lon ) / 0.00833333333333
Kelly Dean
Fort Collins, Colorado
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| Re: Returning Land Type [message #51826 is a reply to message #51800] |
Thu, 07 December 2006 06:38  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Lloyd writes:
> I'm struggling with a mapping problem. I've got the mapping routines
> running, but what I'd like to be able to do is to give IDL some
> coordinates (lat/long) and have it return the ground type (e.g.
> vegetation, ocean, snow, etc - maybe not that detailled).
>
> Has anyone come across this, or done something similar?
I'd be careful about confusing the data with the *display*
of the data. But, presuming you can distinguish these
properties on the basis of some property, say color,
you could take a snapshot of your entire window.
Then you could use CONVERT_COORD to convert your lat/lon
coordinates to device coordinates, and use those to
look up the color in your snapshot. That should tell
you how how that pixel is colored.
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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