[OSGeo-Discuss] Atmospheric Corrections

Markus Neteler neteler at osgeo.org
Fri Jan 27 15:11:53 EST 2012


On Fri, Jan 27, 2012 at 6:13 PM, Johan Oldekop <j.oldekop at gmx.net> wrote:
> Hi All,
>
> Currently trying to do some atmospheric corrections on some Landsat 7 and
> ASTER images to compare forest cover over two time points. I am thinking of
> using the GRASS i.atcorr function, which seems relatively straight forward.

Yes. There is also a related Wiki page:
http://grass.osgeo.org/wiki/Atmospheric_correction

> Unfortunately I do not have the the visibility [km] for the scenes. Is there
> a way of calculating these from the images? Are there any tables that one
> can look up, which contain approximate visibility ranges for "very hazy",
> "moderately hazy" or "low hazy" conditions? Or simply, is there a better,
> and easier way of doing these corrections?

So far I did not find an elegant way (but I didn't try too hard).
Tasseled Cap Transform offers a "haze" channel but I would not know how to
translate it to something useful for i.atcorr, see the related Addons
description page:

https://svn.osgeo.org/grass/grass-addons/grass6/imagery/i.landsat.dehaze/description.html

I wonder if anyone has experience to use MODIS atmosphere aerosol
optical thickness
as visibility, e.g. in
http://modis-atmos.gsfc.nasa.gov/MOD08_D3/format_c51.html
?

Markus

-- 
http://gis.cri.fmach.it/neteler/


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