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Re: Gridded MODIS lat/lon array [message #88191 is a reply to message #88187]

Thu, 27 March 2014 06:13

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

ddt88 writes:

> Hello David, I'm working with a large number of files so I want to avoid having to convert each hdf to geotiff for processing efficiency. I'm quite confused with the geotiff info and can't understand how I could extract the same information from the metadata of HDF files.

The information to navigate the image is in the metadata of the HDF
file. You are given the projection information (Sinusodial with
spherical datum) and the projected XY meter locations of the upper left
point and the lower right point of the image. Then, you are told the
dimensions of the image (4800x4800 in my case). This is everything you
need to know to navigate the image. For example, for the MOD09GQ image I
have here, I set the map coordinate object up like this:

IDL> map =cgmap('sinusoidal', ellipsoid=9, $
xrange=[6671703.118000d, 7783653.637667d], $
yrange=[3335851.559000d, 4447802.078667d], $
position=[0,0,1,1])
IDL> cgDisplay, 800, 800
IDL> cgImage, image, Stretch=2
IDL> cgMap_Grid, /Label, /cgGrid, Color='goldenrod', Map=map

I'm not sure why you think you need to make a GeoTiff file out of it for
"processing efficiency".

I read the information out of the file with NCDF_Browser. But, I'm sure
it is possible to read the metadata out of the file directly, too.

Cheers,

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

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[Message index]

		Gridded MODIS lat/lon array By: dm_gty88 on Wed, 26 March 2014 03:20
		Re: Gridded MODIS lat/lon array By: Andy Sayer on Wed, 26 March 2014 05:42
		Re: Gridded MODIS lat/lon array By: dm_gty88 on Wed, 26 March 2014 18:44
		Re: Gridded MODIS lat/lon array By: Andy Sayer on Thu, 27 March 2014 06:06
		Re: Gridded MODIS lat/lon array By: David Fanning on Wed, 26 March 2014 06:05
		Re: Gridded MODIS lat/lon array By: dm_gty88 on Wed, 26 March 2014 18:46
		Re: Gridded MODIS lat/lon array By: David Fanning on Thu, 27 March 2014 06:13
		Re: Gridded MODIS lat/lon array By: David Fanning on Thu, 27 March 2014 07:06

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