[GRASS-user] GRASS 6.4.3 - Technical questions on Landsat TM/ETM+/OLI and other

[Nuno Sá]

Hey!

This is my first post, unfortunate it's not to help somebody but to ask for
some help.. I do have to say, GRASS seems to be great so far and I feel my
problems are probably user related.

I am pre-processing Landsat data (at the moment only TM and ETM) to use for
a classification later, doesn't matter.

Since all the data I'm acquiring comes as L1T  (204/032), then the
pre-processing workflow was done as follows:

DN -> TOA reflectance(&temperature) -> Cloud detection and masking (if
necessary) -> Topographic correction using ASTERM 30m DEM.

All data projection is as delivered by USGS (I don't remember if I
reprojected the DEM but most probably I did).

Imagery dates - 204/32:

TM4 - 1989001 (January 1, 1989)
TM5 - 2007027 (January 27,2007)
ETM+ - 2003023 (January 23,2003)


All until here seems fine I guess, but I am having the following issues:


   - Band seems saturated or affected by some "multiplier". Such as TM4
   composites look "normal" or as expected but TM5 and ETM+ seem pinkish or
   saturated as if one of the bands is saturated.
   - Since TM4 looks the most "normal", all the others seem affected by
   some kind of noise (white noise?). Should I apply a Low pass filter of some
   kind?
   - Both i.landsat.rgb (runs endlessly) and i.landsat.dehaze (says it
   can't find the GUI, I've re-installed it without success)


If you need added information, please ask and I'll send you the commands.
Here are the ones who generated the attached image:


-------------------

Calling the file
r.in.gdal
input=C:\Invader_B\GRASS_Workfolder_01\01_LT5\LT52040322007027MPS00\LT52040322007027MPS00_B1.TIF
output=RAW_2007027_LT5_B.1

(...)

(i used DOS2 in this latest attempt since both uncorrected and DOS1 yield
similar problems)
i.landsat.toar sensor=tm5 method=dos2 --overwrite --verbose
input_prefix=RAW_2007027_LT5_B. output_prefix=2007027_LT5_B.
metfile=C:\Invader_B\GRASS_Workfolder_01\01_LT5\LT52040322007027MPS00\LT52040322007027MPS00_MTL.txt


i.landsat.acca --overwrite --verbose -5 input_prefix=2007027_LT5_B.
output=2007027_CloudMask
(The mask is not used by me since i visually see there are no clouds [there
is snow in Serra da Estrela, famous place here])

Getting the illumination raster
i.topo.corr -i --overwrite base=ASTER_30m zenith=63.09559142
azimuth=153.85758094 out=ASTER.illu.prj

i.topo.corr base=ASTER.illu.prj zenith=63.09559142 method=c-factor
--verbose --overwrite
input=2007027_LT5_B.1,2007027_LT5_B.2,2007027_LT5_B.3,2007027_LT5_B.4,2007027_LT5_B.5,2007027_LT5_B.6,2007027_LT5_B.7
out=npca_topo_CM

r.colors -e map=npca_topo_CM.2007027_LT5_B.1 at 01_LT5 color=grey
(...)

d.rgb to display the image in attachment.

-------------------------------------------------------------
-- 

Nuno César de Sá
+351 91 961 90 37
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