[GRASS-user] R: NULL values as output of i.atcorr

[ilaria.ferrando87 at gmail.com]

Dear Moritz,
thank you for your reply.
I tried with and without the -r flag and the results is the same.
Please find attached the parameters of the file 22giugno2020_b4.txt:

26
6 22 17.05 9.68728523 43.75514951
2
1 
0
-0.293
-1000
182

Best regards,
	ilaria

-----Messaggio originale-----
Da: Moritz Lennert <mlennert at club.worldonline.be> 
Inviato: giovedì 27 gennaio 2022 13:22
A: Ilaria Ferrando <ilaria.ferrando87 at gmail.com>; Maris Nartiss <maris.gis at gmail.com>
Cc: GRASS user list <grass-user at lists.osgeo.org>
Oggetto: Re: [GRASS-user] NULL values as output of i.atcorr

On 26/01/22 19:50, Ilaria Ferrando wrote:
> Dear Māris,
> Thank you for your reply.
> Yes, the image is inside the computational region.
> Any other ideas?


1) Are you sure your input data is reflectance (-r flag used) ?
2) Could you provide us with the contents of the 22giugno2020_b4.txt file ?

Moritz

> 
> Il mer 26 gen 2022, 19:45 Maris Nartiss <maris.gis at gmail.com 
> <mailto:maris.gis at gmail.com>> ha scritto:
> 
>     One thing to always check – does your computational region contain
>     data you are analysing? Try to run `g.region rast=immagine` before
>     running i.atcorr.
> 
>     Māris.
> 
>     trešd., 2022. g. 26. janv., plkst. 18:13 — lietotājs
>     <ilaria.ferrando87 at gmail.com <mailto:ilaria.ferrando87 at gmail.com>>
>     rakstīja:
>      >
>      > Dear all,
>      >
>      > I am having troubles in processing a Sentinel-2 image with i.atcorr.
>      >
>      > The command I use is the following:
>      >
>      > i.atcorr -r -input=immagine at mapset range=0,10000
>     parameters=C:\...\22giugno2020_b4.txt output=immagine_atcorr rescale=0,1
>      >
>      > and I obtain this output:
>      >
>      > wavelength less than 0.25 micron:
>      >
>      > let's take s(l)=s(0.25)
>      >
>      > Atmospheric correction...
>      >
>      > Atmospheric correction complete.
>      >
>      >
>      >
>      > The map I obtain is constituted by pixels with 6.669033e-34 values.
>      >
>      > Can anyone explain the meaning of the output and why I obtain a
>     NULL value corrected map?
>      >
>      > Thank you for your support.
>      >
>      >
>      >
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