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Re: extract lat/lon from MOD13Q1 [message #60889]

Tue, 17 June 2008 06:31

wita
Messages: 43
Registered: January 2005

Member

mtschnur wrote:
> Hello, I'm experienced in ENVI but new to IDL. I need to extract NDVI,
> EVI, and VI Quality from about 75 datasets at 7 lat/lon coordinates
> per date. I can do this individually in ENVI by opening the images,
> but it is a tedious and error-prone task. I am sure IDL would make
> this easier and more accurate. Can anyone help?
>
> Thanks, Mark

Hi Mark,

If these 7 lat/lon coordinates are the same for each image, then the
job would be easy in ENVI:
- Stack all 75 images, be careful keep the date order correctly in the
stack
- Start a Z-profile and go to the lan/lon of interest
- Export the Z-profile as an IDL variable or ASCII file.

You can do it programatically as well by using
ENVI_CONVERT_PROJECTION_COORDINATES to convert from lat/lon to
whatever projection your image data is in and
ENVI_CONVERT_FILE_COORDINATES to convert from map to file coordinates.
The data values can be retrieved by using the file coordinates as
indexes into the image array.

with best regards,

Allard

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		Re: extract lat/lon from MOD13Q1 By: wita on Tue, 17 June 2008 06:31
		Re: extract lat/lon from MOD13Q1 By: Jelle on Mon, 16 June 2008 10:57

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