[GRASS-user] i.atcorr returns empty Raster in GRASS 7

[Xavier de Lamo]

Many thanks for your help. This is the i.landsat.toar command:

i.landsat.toar --overwrite input_prefix=LakeChirwaN_B
output_prefix=LakeChirwaN_REFL metfile="/Users/xavi/Desktop/Lake Chirwa
Landsat /Landsat 7/Level 1
Product/LakeChirwaN/LE71670702002146SGS00_MTL.txt"


and this are the range of values for the first 4 bands. As you can see, all
of them includes small negative values, maybe this is the problem. Should I
mask them before applying i.atcorr?


r.info -r LakeChirwaN_REFL1

min=-0.0111266691078146

max=0.459205333674142


r.info -r
LakeChirwaN_REFL2
min=-0.0164141835709247
max=0.503966729951046



r.info -r
LakeChirwaN_REFL3
min=-0.0133215715423686
max=0.465214050321331



r.info -r
LakeChirwaN_REFL4
min=-0.023052966150257
max=1.0898176742798


I have double-checked the parameters of the control file and I did spot an
error (the order of the latitude longitude values is inversed), however,
correcting this did not solve the problem when I performed te operation
again.


Others values seems to be OK (the time value is the time provided in the
metadata file converted to decimal time, and, according to the GRASS manual
0 value should be entered for visibility when an estimate for aerosol
optical depth is available (I obtained this estimate from MODIS
MOD08-Gridded Atmospheric Product.


2014/1/7 Markus Neteler <neteler at osgeo.org>

> On Mon, Jan 6, 2014 at 11:11 PM, Xavier de Lamo <xavi.delamo at gmail.com>
> wrote:
> > Dear all,
> >
> > I am recent GRASS GIS user who is trying to run the i.atcorr module to
> > atmospherically correct a Landsat ETM+ image in GRASS 7 (on MacBook Pro,
> > Mavericks OSX). This image has been already converted to reflectance with
> > i.landsat. toar.
>
> Could you please post here the range values of the first four
> channels? Something like
> r.info -r channelX
> (or use the GUI)
>
> Just to be sure that the i.landsat. toar output is right.
>
> > I also use a DEM file obtained from ASTER GDEM. All these
> > files are projected to UTM zone 36 S.
> > I have followed the steps described in the manual and everything seems
> to be
> > fine except that the process returns an empty raster (all raster values
> > equal to NoData).
> >
> >  This is the command:
>
> Please also post the i.landsat.toar command here.
>
>
> > i.atcorr –r –a input= LakeChirwaN-REFL1 at Malawi
> > parameters=/Users/Xavi/Desktop/LCDM.txt output=LakeChirwaN_REFL1_ATCORR
> >
> > And the LCDM file looks like this:
> >
> >
> >
> > 8                                               -- Landsat ETM+
> > 5 26 7.487 35.753 -14.414  -- month day hh.ddd longitude latitude
>
> Is the order of longitude and latitude right?
> The hh.ddd is in correct GMT?
>
> > 1                                               -- Atmospheric model:
> tropical
> > 0                                               -- Visibility
>
> Zero visibility mean full darkness? :-)
>
> > -0.009                                      -- Aerosol Optical Depth 550
> nm
> > -0.650                                      -- Mean target elevation (in
> Km) *-1
> > -1000                                       -- Sensor height (on board a
> satellite)
> >
> > 61                                            -- Sensor band (ETM+ band
> 1)
> >
> > Could someone give help me on this please?
>
> Please doublecheck the parameters in the control file.
>
> Markus
>
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