[GRASS-user] Re: i.atcorr returns all NULL values

[Markus Metz]

On Mon, May 23, 2011 at 9:36 PM, Markus Neteler <neteler at osgeo.org> wrote:
> Hi Yann,
>
> On Mon, May 23, 2011 at 5:07 AM, Chemin, Yann (IWMI) <Y.Chemin at cgiar.org> wrote:
>> p192 r030 image of July 2003 of Italy (L5TM) successfully corrected for
>> band 1 and 2.
>> The following script works well in GRASS GIS Trunk SVN.
>
> (better send as attachment since a series of line breaks got broken)
>
> ...
>> # For i.atcorr scripting
>> #-----------------------------------------------------
>> vis_list=(10 10 8 9.7 15 8 7 10 10 9.7 12 9.7 7 12 12 12 3 15 12 9.7 6 15)
>> vis_len=${#vis_list[*]}
>> echo $vis_len
>
> ... this is not clear to me: why so many values and where
> do they originate from? Since we have only 6 channels to
> work with...
>
Moreover, how can it be possible that visibility is different for
different channels of the same scene? From the documentation it seems
that visibility is related to aerosol concentration at 550nm which can
not possibility be different for different bands of the same scene.
Each created visibility map holds only one value
r.mapcalc expression="visibility=${vis_list[$i]}" --overwrite
so why not just use this visibility value as input in the parameter
file instead of creating a map where all cells have the same value?

Markus M