<div dir="ltr">Dear Stefan <div><br></div><div>I have applied i.atcorr to many S2A scenes last year and it worked. Today I rechecked them again, and it worked on a older svn version (7.3) and also on the latest trunk version. </div><div><br></div><div>All the steps I have taken is similar to what you have done, so I dont really know whats going wrong with you.</div><div><br></div><div>Here is the command I used:</div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">i.atcorr -r input="S2A_OPER_MSI_L1C_TL_MTI_20151012T101024457Z_T32TPR_B02" range=0,10000 elevation="eudem_euregio_utm32_10m" parameters="S2_B02_T32TPR.txt" output="S2A_OPER_MSI_L1C_TL_MTI_20151012T101024457Z_T32TPR_02_6S" rescale=0,10000<br></blockquote><div><br></div><div> </div><div>S2_B02_T32TPR.txt:<br></div><div><img src="cid:ii_1606e89632d28359" alt="Inline image 1" width="241" height="164"><br></div><div><br></div><div><br></div><div>The AOD value is coming from the output of Sen2cor (It was a trial approach !). I tried with a visibility value of 15 and it works.</div><div><br></div><div>And the ouput of r.univar is:</div><div><br></div><div><img src="cid:ii_1606e8bc99efee2d" alt="Inline image 2" width="563" height="188"><br></div><div><br></div><div><br></div><div>I also tried it on a smaller clip (1000 X 1000), and it is giving some output.</div><div><br></div><div>Let me know if you need any more info.</div><div><br></div><div>Regards</div><div><br></div><div>Sajid</div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Dec 19, 2017 at 11:33 AM, Stefan Blumentrath <span dir="ltr"><<a href="mailto:Stefan.Blumentrath@nina.no" target="_blank">Stefan.Blumentrath@nina.no</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi again,<br>
<br>
Even with constant spectral conditions and values for filter function from Sentinel-2, all combinations of input band ranges result in empty maps.<br>
Constant spectral conditions and values for filter function from Landsat7 however, give results in the expected scale (0-255) regardless input image and value ranges...<br>
<br>
Shall I open a ticket?<br>
<br>
Any idea/chance to get this new feature in G7.4 to work...?<br>
<br>
Any pointer/help would be very much appreciated!<br>
<br>
Cheers<br>
<span class="HOEnZb"><font color="#888888">Stefan<br>
</font></span><span class="im HOEnZb"><br>
-----Original Message-----<br>
From: Stefan Blumentrath<br>
Sent: tirsdag 19. desember 2017 10.56<br>
To: Stefan Blumentrath <<a href="mailto:Stefan.Blumentrath@nina.no">Stefan.Blumentrath@nina.no</a>>; Moritz Lennert <<a href="mailto:mlennert@club.worldonline.be">mlennert@club.worldonline.be</a>><wbr>; Žofie Cimburová <<a href="mailto:zoficimburova@gmail.com">zoficimburova@gmail.com</a>><br>
Cc: GRASS user list <<a href="mailto:grass-user@lists.osgeo.org">grass-user@lists.osgeo.org</a>><br>
</span><div class="HOEnZb"><div class="h5">Subject: RE: [GRASS-user] i.atcorr with Sentinel2<br>
<br>
Hi again,<br>
<br>
Still trying to track down the issue...<br>
I now ran i.atcorr with constant spectral condition and manually defined "wl inf" and "wl sup".<br>
<br>
First I got those values for Sentinel-2 band 2:<br>
* spectral condition *<br>
* ------------------ *<br>
* sentinel2a blue b2 *<br>
* value of filter function : *<br>
* wl inf= 0.300 mic wl sup= 2.600 mic *<br>
<br>
Then for Landsat 7 band 4 (that was known to give results):<br>
* spectral condition *<br>
* ------------------ *<br>
* etm+ 4 *<br>
* value of filter function : *<br>
* wl inf= 0.740 mic wl sup= 0.913 mic *<br>
<br>
<br>
If I then feed those values into a filter function for constant spectral conditions, and again the Sentinel-2 values:<br>
* spectral condition *<br>
* ------------------ *<br>
* constant *<br>
* value of filter function : *<br>
* wl inf= 0.300 mic wl sup= 2.600 mic *<br>
lead to empty maps, while Landsat7 values:<br>
* spectral condition *<br>
* ------------------ *<br>
* constant *<br>
* value of filter function : *<br>
* wl inf= 0.740 mic wl sup= 0.913 mic *<br>
work fine (with all other settings being equal).<br>
<br>
That makes me suspect that the values of the Sentinel-2 filter function are actually causing the issue here...<br>
I am currently testing all thinkable combinations of input band ranges to see if any of them works with wl inf=0.300 mic and wl sup=2.600 mic and will report back from that exercise.<br>
<br>
Meanwhile, can anyone confirm that i.atcorr in GRASS 7.4.0RC1 actually works with Sentinel-2 data?<br>
<br>
Cheers<br>
Stefan<br>
<br>
<br>
<br>
-----Original Message-----<br>
From: grass-user [mailto:<a href="mailto:grass-user-bounces@lists.osgeo.org">grass-user-bounces@<wbr>lists.osgeo.org</a>] On Behalf Of Stefan Blumentrath<br>
Sent: tirsdag 19. desember 2017 08.45<br>
To: Moritz Lennert <<a href="mailto:mlennert@club.worldonline.be">mlennert@club.worldonline.be</a>><wbr>; Žofie Cimburová <<a href="mailto:zoficimburova@gmail.com">zoficimburova@gmail.com</a>><br>
Cc: GRASS user list <<a href="mailto:grass-user@lists.osgeo.org">grass-user@lists.osgeo.org</a>><br>
Subject: Re: [GRASS-user] i.atcorr with Sentinel2<br>
<br>
Hi again,<br>
<br>
A little update on the problem:<br>
Now I ran i.atcorr with all possible band values for Sentinel-2 in the 6s parameters (166-178) with input maps ranges scaled to 0-1, 0-255, <a href="tel:0-10000" value="+39010000">0-10000</a> All runs resulted in completely empty maps!<br>
Any ideas?<br>
<br>
Thanks for helping in advance!<br>
<br>
Kind regards,<br>
Stefan<br>
<br>
-----Original Message-----<br>
From: Moritz Lennert [mailto:<a href="mailto:mlennert@club.worldonline.be">mlennert@club.<wbr>worldonline.be</a>]<br>
Sent: mandag 18. desember 2017 16.58<br>
To: Stefan Blumentrath <<a href="mailto:Stefan.Blumentrath@nina.no">Stefan.Blumentrath@nina.no</a>>; Žofie Cimburová <<a href="mailto:zoficimburova@gmail.com">zoficimburova@gmail.com</a>><br>
Cc: GRASS user list <<a href="mailto:grass-user@lists.osgeo.org">grass-user@lists.osgeo.org</a>><br>
Subject: Re: [GRASS-user] i.atcorr with Sentinel2<br>
<br>
On 18/12/17 16:35, Stefan Blumentrath wrote:<br>
> Hi Moritz,<br>
><br>
> Thanks for helping with troubleshooting!<br>
> QUANTIFICATION_VALUE is 10000, Thus dividing with it gives a maximum value of 2.8...<br>
> Any idea how to figure out if it is 12 or 16 bit image. It is directly downloaded from ESA...<br>
<br>
Check which proportion of the image is > 1. AFAIR (which is a bit limited), you might have reflectances above 1 in saturated pixels. I just checked on a random image and I also have some pixels above 1, but only 0.25% of the pixels:<br>
<br>
GRASS 7.5.svn (UTM32N):/data/home/mlennert > r.mapcalc "test = if(b04_refl>1,1,0)"<br>
100%<br>
GRASS 7.5.svn (UTM32N):/data/home/mlennert > r.stats -cp test<br>
100%<br>
0 120259106 99.75%<br>
1 301294 0.25%<br>
<br>
And all the pixels with value 1 are in clouded areas.<br>
<br>
Moritz<br>
<br>
><br>
> Cheers<br>
> Stefan<br>
><br>
> -----Original Message-----<br>
> From: grass-user [mailto:<a href="mailto:grass-user-bounces@lists.osgeo.org">grass-user-bounces@<wbr>lists.osgeo.org</a>] On Behalf<br>
> Of Moritz Lennert<br>
> Sent: mandag 18. desember 2017 16.26<br>
> To: Žofie Cimburová <<a href="mailto:zoficimburova@gmail.com">zoficimburova@gmail.com</a>><br>
> Cc: GRASS user list <<a href="mailto:grass-user@lists.osgeo.org">grass-user@lists.osgeo.org</a>><br>
> Subject: Re: [GRASS-user] i.atcorr with Sentinel2<br>
><br>
> On 18/12/17 16:13, Žofie Cimburová wrote:<br>
>> Dear Moritz,<br>
>><br>
>> According to<br>
>> <a href="https://earth.esa.int/web/sentinel/user-guides/sentinel-2-msi/product" rel="noreferrer" target="_blank">https://earth.esa.int/web/<wbr>sentinel/user-guides/sentinel-<wbr>2-msi/product</a><br>
>> - types , the L1C product I am using already is in top of atmosphere<br>
>> reflectance, so this should not be the problem (?).<br>
>> I tried running i.atcorr both with and without the -r flag.<br>
><br>
> Reflectance is the percentage of light that is reflected either from<br>
> the top of the atmosphere or from the surface. Reflectance values<br>
> should thus be real values between 0 and 1. Your data have<br>
><br>
> Range of data: min = 1 max = 28000<br>
><br>
> This means that they are expressed in digital (integer) numbers. Try transforming these DN into real numbers. IIRC, in the metadata, you have a variable QUANTIFICATION_VALUE. Divide your pixel values by that value to get real TOA reflectance values.<br>
><br>
> AFAIK, it also depends on whether you directly imported the original 12-bit file, or possibly a modified, e.g. 16-bit, version.<br>
><br>
> Moritz<br>
><br>
>> On Mon, Dec 18, 2017 at 3:35 PM, Moritz Lennert<br>
>> <<a href="mailto:mlennert@club.worldonline.be">mlennert@club.worldonline.be</a> <mailto:<a href="mailto:mlennert@club.worldonline.be">mlennert@club.<wbr>worldonline.be</a>>> wrote:<br>
>><br>
>> On 18/12/17 13:14, Žofie Cimburová wrote:<br>
>><br>
>> Hi all,<br>
>> Now the 6S parameters are complete, but the output map contains<br>
>> only NULLs, no matter what combinations of input parameters and<br>
>> flags I use. Have anyone encountered the same issue? (Info<br>
>> below.)<br>
>><br>
>><br>
>> In the i.atcorr man page it says:<br>
>><br>
>> "If flag -r is used, the input raster data are treated as<br>
>> reflectance. Otherwise, the input raster data are treated as<br>
>> radiance values"<br>
>><br>
>> IIUC, your data is still in DN. You might want to try to transform<br>
>> this into radiance values before sending it into i.atcorr.<br>
>><br>
>> Moritz<br>
>><br>
>><br>
>> Thanks again.<br>
>> Zofie<br>
>><br>
>> ------------------------------<wbr>----------<br>
>> Version:<br>
>> g.version -g<br>
>> version=7.4.0RC1<br>
>> date=2017<br>
>> revision=exported<br>
>> build_date=2017-11-18<br>
>> build_platform=x86_64-pc-<wbr>linux-gnu<br>
>> build_off_t_size=8<br>
>><br>
>> ------------------------------<wbr>----------<br>
>> Region:<br>
>> g.region -p<br>
>> projection: 1 (UTM)<br>
>> zone: 33<br>
>> datum: etrs89<br>
>> ellipsoid: grs80<br>
>> north: 6653695<br>
>> south: 6643685<br>
>> west: 256495<br>
>> east: 266505<br>
>> nsres: 10<br>
>> ewres: 10<br>
>> rows: 1001<br>
>> cols: 1001<br>
>> cells: 1002001<br>
>><br>
>> ------------------------------<wbr>----------<br>
>> Input data: Sentinel2 L1C product B02 (tried with B01 too)<br>
>> <a href="http://r.info" rel="noreferrer" target="_blank">r.info</a> <<a href="http://r.info" rel="noreferrer" target="_blank">http://r.info</a>> <<a href="http://r.info" rel="noreferrer" target="_blank">http://r.info</a>><br>
>> map=test_B02@p_<wbr>Sentinel4Nature_S2_Oslo<br>
>> +---------------------------<wbr>------------------------------<wbr>-------------------+<br>
>> | Map: test_B02@p_Sentinel4Nat Date: Wed Dec 6<br>
>> 12:06:39 2017<br>
>> | Mapset: p_Sentinel4Nature_S2_Oslo Login of Creator:<br>
>> stefan.blumentr<br>
>> | Location: ETRS_33N<br>
>> | DataBase: /data/grass<br>
>> | Title:<br>
>> S2A_OPER_PRD_MSIL1C_PDMC_<wbr>20160907T044118_R008_<wbr>V20160905T104022_2<br>
>> | Timestamp: none<br>
>> |---------------------------<wbr>------------------------------<wbr>-------------------|<br>
>> |<br>
>> | Type of Map: raster Number of Categories: 0<br>
>> | Data Type: CELL<br>
>> | Rows: 1001<br>
>> | Columns: 1001<br>
>> | Total Cells: 1002001<br>
>> | Projection: UTM (zone 33)<br>
>> | N: 6653695 S: 6643685 Res: 10<br>
>> | E: 266505 W: 256495 Res: 10<br>
>> | Range of data: min = 1 max = 28000<br>
>> |<br>
>> | Data Description:<br>
>> | generated by r.in.gdal<br>
>><br>
>> +-----------------------------<wbr>------------------------------<wbr>---------<br>
>> +-<br>
>> -------+<br>
>><br>
>> ------------------------------<wbr>----------<br>
>> 6s file:<br>
>> 25- geometrical conditions=Sentinel-2A<br>
>> 9 5 10.6728 10.73413 59.90647- month day hh.ddd longitude latitude<br>
>> 4 - atmospheric model=subarctic summer<br>
>> 3- aerosol model=urban<br>
>> 50- visibility [km] (aerosol model concentration) (this is<br>
>> estimated, I also tried with AOD specified)<br>
>> -0.055- mean target elevation above sea level [km]<br>
>> -1000- sensor height<br>
>> 166- Sentinel2A Blue band B2 (440nm - 535nm)<br>
>><br>
>> ------------------------------<wbr>----------<br>
>> Command:<br>
>> i.atcorr input=test_B02@p_<wbr>Sentinel4Nature_S2_Oslo range=1,28000<br>
>> elevation=dem_10m_25833@p_<wbr>Sentinel4Nature_S2_Oslo<br>
>> parameters=/home/<a href="http://NINA.NO/zofie.cimburova/Sentinel4Nature/DATA/6s.txt" rel="noreferrer" target="_blank">NINA.NO/<wbr>zofie.cimburova/<wbr>Sentinel4Nature/DATA/6s.txt</a><br>
>> <<a href="http://NINA.NO/zofie.cimburova/Sentinel4Nature/DATA/6s.txt" rel="noreferrer" target="_blank">http://NINA.NO/zofie.<wbr>cimburova/Sentinel4Nature/<wbr>DATA/6s.txt</a>><br>
>> <<a href="http://NINA.NO/zofie.cimburova/Sentinel4Nature/DATA/6s.txt" rel="noreferrer" target="_blank">http://NINA.NO/zofie.<wbr>cimburova/Sentinel4Nature/<wbr>DATA/6s.txt</a><br>
>> <<a href="http://NINA.NO/zofie.cimburova/Sentinel4Nature/DATA/6s.txt" rel="noreferrer" target="_blank">http://NINA.NO/zofie.<wbr>cimburova/Sentinel4Nature/<wbr>DATA/6s.txt</a>>><br>
>> output=test_B02_atcorr<br>
>> >Atmospheric correction...<br>
>> >Atmospheric correction complete.<br>
>><br>
>> (I am not sure about the range parameter, tried with 0,255 too.<br>
>> The DEM contains no NULLs. Also tried running with -r and -a<br>
>> flags.)<br>
>><br>
>> ------------------------------<wbr>----------<br>
>> Output:<br>
>> <a href="http://r.info" rel="noreferrer" target="_blank">r.info</a> <<a href="http://r.info" rel="noreferrer" target="_blank">http://r.info</a>> <<a href="http://r.info" rel="noreferrer" target="_blank">http://r.info</a>><br>
>> map=test_B02_atcorr@p_<wbr>Sentinel4Nature_S2_Oslo<br>
>> +---------------------------<wbr>------------------------------<wbr>-------------------+<br>
>> | Map: test_B02_atcorr@p_Sentinel4N Date: Mon Dec 18<br>
>> 13:10:14 2017<br>
>> | Mapset: p_Sentinel4Nature_S2_Oslo Login of Creator:<br>
>> zofie.cimburova<br>
>> | Location: ETRS_33N<br>
>> | DataBase: /data/grass<br>
>> | Title: test_B02_atcorr2<br>
>> | Timestamp: none<br>
>> |---------------------------<wbr>------------------------------<wbr>-------------------|<br>
>> |<br>
>> | Type of Map: raster Number of Categories: 0<br>
>> | Data Type: FCELL<br>
>> | Rows: 1001<br>
>> | Columns: 1001<br>
>> | Total Cells: 1002001<br>
>> | Projection: UTM (zone 33)<br>
>> | N: 6653695 S: 6643685 Res: 10<br>
>> | E: 266505 W: 256495 Res: 10<br>
>> | Range of data: min = -nan max = -nan<br>
>> |<br>
>> | Data Description:<br>
>> | generated by i.atcorr<br>
>> |<br>
>> | Comments:<br>
>> | i.atcorr input="test_B02@p_<wbr>Sentinel4Nature_S2_Oslo"<br>
>> range=1,28\<br>
>> | 000 elevation="dem_10m_25833@p_<wbr>Sentinel4Nature_S2_Oslo"<br>
>> para\<br>
>> |<br>
>> meters="/home/<a href="http://NINA.NO/zofie.cimburova/Sentinel4Nature/DATA/6s.txt" rel="noreferrer" target="_blank">NINA.NO/zofie.<wbr>cimburova/Sentinel4Nature/<wbr>DATA/6s.txt</a> <<a href="http://NINA.NO/zofie.cimburova/Sentinel4Nature/DATA/6s.txt" rel="noreferrer" target="_blank">http://NINA.NO/zofie.<wbr>cimburova/Sentinel4Nature/<wbr>DATA/6s.txt</a>><br>
>> <<a href="http://NINA.NO/zofie.cimburova/Sentinel4Nature/DATA/6s.txt" rel="noreferrer" target="_blank">http://NINA.NO/zofie.<wbr>cimburova/Sentinel4Nature/<wbr>DATA/6s.txt</a><br>
>> <<a href="http://NINA.NO/zofie.cimburova/Sentinel4Nature/DATA/6s.txt" rel="noreferrer" target="_blank">http://NINA.NO/zofie.<wbr>cimburova/Sentinel4Nature/<wbr>DATA/6s.txt</a>>>" o\<br>
>> | utput="test_B02_atcorr2" rescale=0,255<br>
>> |<br>
>><br>
>> +-----------------------------<wbr>------------------------------<wbr>---------<br>
>> +-<br>
>> -------+<br>
>><br>
>><br>
>><br>
>> On Fri, Dec 15, 2017 at 5:12 PM, Žofie Cimburová<br>
>> <<a href="mailto:zoficimburova@gmail.com">zoficimburova@gmail.com</a> <mailto:<a href="mailto:zoficimburova@gmail.com">zoficimburova@gmail.<wbr>com</a>><br>
>> <mailto:<a href="mailto:zoficimburova@gmail.com">zoficimburova@gmail.<wbr>com</a><br>
>> <mailto:<a href="mailto:zoficimburova@gmail.com">zoficimburova@gmail.<wbr>com</a>>>> wrote:<br>
>><br>
>> Dear Markus,<br>
>> thanks for your reply, this is exactly what I need to know!<br>
>><br>
>> Best, Zofie<br>
>><br>
>> On Fri, Dec 15, 2017 at 5:09 PM, Markus Neteler<br>
>> <<a href="mailto:neteler@osgeo.org">neteler@osgeo.org</a> <mailto:<a href="mailto:neteler@osgeo.org">neteler@osgeo.org</a>><br>
>> <mailto:<a href="mailto:neteler@osgeo.org">neteler@osgeo.org</a> <mailto:<a href="mailto:neteler@osgeo.org">neteler@osgeo.org</a>>>> wrote:<br>
>><br>
>><br>
>> On Dec 15, 2017 3:54 PM, "Žofie Cimburová"<br>
>> <<a href="mailto:zoficimburova@gmail.com">zoficimburova@gmail.com</a><br>
>> <mailto:<a href="mailto:zoficimburova@gmail.com">zoficimburova@gmail.<wbr>com</a>> <mailto:<a href="mailto:zoficimburova@gmail.com">zoficimburova@gmail.<wbr>com</a><br>
>> <mailto:<a href="mailto:zoficimburova@gmail.com">zoficimburova@gmail.<wbr>com</a>>>> wrote:<br>
>> ><br>
>> > Dear all,<br>
>> > I am trying to use i.atcorr (GRASS 7.4) to apply<br>
>> atmospheric corrections for Sentinel 2 data. The documentation<br>
>> provides a great help, but there are two points I am not sure<br>
>> about - ><br>
>> > - I don't need the atmospheric correction to be<br>
>> applied to the whole scene, so I only imported a small clip of<br>
>> the scene to GRASS. What longitude and latitude shall I then<br>
>> specify in the 6S parameters?<br>
>><br>
>> I'd use the center coordinates of the clipped area.<br>
>><br>
>> > Or is it necessary to apply the corrections to the<br>
>> entire scene?<br>
>><br>
>> No since it is a pixel based algorithm.<br>
>><br>
>> > - How can I estimate the value of visibility (aerosol<br>
>> model concentration)?<br>
>> There are AERONET data online somewhere which might be<br>
>> the best<br>
>> choice.<br>
>><br>
>> Markus<br>
>><br>
>><br>
>><br>
>><br>
>><br>
>> ______________________________<wbr>_________________<br>
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>> <a href="https://lists.osgeo.org/mailman/listinfo/grass-user" rel="noreferrer" target="_blank">https://lists.osgeo.org/<wbr>mailman/listinfo/grass-user</a><br>
>> <<a href="https://lists.osgeo.org/mailman/listinfo/grass-user" rel="noreferrer" target="_blank">https://lists.osgeo.org/<wbr>mailman/listinfo/grass-user</a>><br>
>><br>
>><br>
>><br>
>><br>
><br>
><br>
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