[GRASS-user] Pre-processing LANDSAT TM Orthorectified images from GLCF

[maning sambale]

Markus,

> AFAIK LANDSAT is sun-synchronous, it passes in the local morning time
> (something like 10:30-11:00).
>
> Maybe this helps:
> http://earthobservatory.nasa.gov/MissionControl/overpass.html

Since it is an overpass predictor, it doesn't provide information on
previous landsat overpass.  Can I use this as a proxy to the hh:mm for
i.atcorr (me thinks no)?  Or set an arbitrary time say between 10:30
to 11:00?

> i.atcorr is the sophisticated correction, i.landsat.dehaze only a simple
> approach based on image statistics.
>
>> 3. correction for topographic/terrain effects (most of my study area
>> are in maountainous regions)
>> use book 2nd ed. (page 226) "cosine correction"
>> using r.sunmask, r.mapcalc
>> Problem: again, no image acquisition time
>
> (see above). "cosine correction" is a simple approach. See also
> i.topo.corr (from GRASS AddOns).
Thank you for this one.

>> 4. removal of clouds
>> use i.landsat.acca
>> https://svn.osgeo.org/grass/grass-addons/imagery/i.landsat.acca/
>
> Never tried, please report back.
Will do, via wiki.

> I have collected all this now in
> http://grass.osgeo.org/wiki/Image_processing#Preprocessing
>
> Feel free to further improve that Wiki page.
> Markus

As usual, thank you very much.

cheers,
maning

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