| Comparing Pixel Values in Images With IDL [message #49649] |
Wed, 09 August 2006 09:50  |
SeskaLien
Messages: 1
Registered: August 2006
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Junior Member |
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I'd like to apologize if this is a simple question, but I am new to IDL
and haven't had a lot of experience with it yet. I have some GeoTIFF
files created in ENVI (georeferenced MODIS imagery that has been
exported as GeoTIFF files) that I need to compare with one another to
see if there is snow cover in some and not others. The images are
georeferenced and have common points, but do not have the same
dimensions or same complete coverage areas. So, I think I need to find
a way to have IDL read them in and tell me the pixel value at specific
lat/long points common in each image so I can see how the albedo is
changing (the images are taken over a range of time). Could anyone help
me out as to how to go about this? Thank you very much!
~Seska
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| Re: Comparing Pixel Values in Images With IDL [message #49732 is a reply to message #49649] |
Thu, 10 August 2006 03:13  |
Ulan
Messages: 8
Registered: April 2005
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Junior Member |
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If you just need to visually compare two mages you could display both
images and link them by "Geogrphical link" in ENVI window menu (Envi
Image Window->Tools->Geographical Link) . However, If you need to
subset images to have common area covered and to have the same
dimensions, you 'd need to subset via geocoordinates (ENVI Menu->Resize
Data and when Dialog Window pos up ->Spatial Subset nad there choose
Map option and enter geocordinates).
Ulan
SeskaLien wrote:
> I'd like to apologize if this is a simple question, but I am new to IDL
> and haven't had a lot of experience with it yet. I have some GeoTIFF
> files created in ENVI (georeferenced MODIS imagery that has been
> exported as GeoTIFF files) that I need to compare with one another to
> see if there is snow cover in some and not others. The images are
> georeferenced and have common points, but do not have the same
> dimensions or same complete coverage areas. So, I think I need to find
> a way to have IDL read them in and tell me the pixel value at specific
> lat/long points common in each image so I can see how the albedo is
> changing (the images are taken over a range of time). Could anyone help
> me out as to how to go about this? Thank you very much!
>
> ~Seska
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