<div dir="ltr">Hi all,<div>Now the 6S parameters are complete, but the output map contains only NULLs, no matter what combinations of input parameters and flags I use. Have anyone encountered the same issue? (Info below.)</div><div><br></div><div>Thanks again.</div><div>Zofie</div><div><br></div><div>----------------------------------------</div><div>Version:<br></div><div>g.version -g</div><div><div>version=7.4.0RC1</div><div>date=2017</div><div>revision=exported</div><div>build_date=2017-11-18</div><div>build_platform=x86_64-pc-<wbr>linux-gnu</div><div>build_off_t_size=8</div></div><div><br></div><div><div>----------------------------------------</div></div><div>Region:<br></div><div><div>g.region -p </div><div>projection: 1 (UTM)</div><div>zone: 33</div><div>datum: etrs89</div><div>ellipsoid: grs80</div><div>north: 6653695</div><div>south: 6643685</div><div>west: 256495</div><div>east: 266505</div><div>nsres: 10</div><div>ewres: 10</div><div>rows: 1001</div><div>cols: 1001</div><div>cells: 1002001</div></div><div><br></div><div><div>----------------------------------------</div></div><div>Input data: Sentinel2 L1C product B02 (tried with B01 too)<br></div><div><a href="http://r.info">r.info</a> map=test_B02@p_Sentinel4Nature_S2_Oslo<br></div><div> +----------------------------------------------------------------------------+<br></div><div><div> | Map: test_B02@p_Sentinel4Nat Date: Wed Dec 6 12:06:39 2017 </div><div> | Mapset: p_Sentinel4Nature_S2_Oslo Login of Creator: stefan.blumentr </div><div> | Location: ETRS_33N </div><div> | DataBase: /data/grass </div><div> | Title: S2A_OPER_PRD_MSIL1C_PDMC_20160907T044118_R008_V20160905T104022_2 </div><div> | Timestamp: none </div><div> |----------------------------------------------------------------------------|</div><div> | </div><div> | Type of Map: raster Number of Categories: 0 </div><div> | Data Type: CELL </div><div> | Rows: 1001 </div><div> | Columns: 1001 </div><div> | Total Cells: 1002001 </div><div> | Projection: UTM (zone 33) </div><div> | N: 6653695 S: 6643685 Res: 10 </div><div> | E: 266505 W: 256495 Res: 10 </div><div> | Range of data: min = 1 max = 28000 </div><div> | </div><div> | Data Description: </div><div> | generated by r.in.gdal </div><div> +----------------------------------------------------------------------------+</div></div><div><br></div><div><div>----------------------------------------</div></div><div>6s file:<br></div><div>25<span style="white-space:pre"> </span> <span style="white-space:pre"> </span>- geometrical conditions=Sentinel-2A<br></div><div><div>9 5 10.6728 10.73413 59.90647<span style="white-space:pre"> </span>- month day hh.ddd longitude latitude</div><div>4 <span style="white-space:pre"> </span> <span style="white-space:pre"> </span> <span style="white-space:pre"> </span>- atmospheric model=subarctic summer</div><div>3<span style="white-space:pre"> </span>- aerosol model=urban</div><div>50<span style="white-space:pre"> </span>- visibility [km] (aerosol model concentration) (this is estimated, I also tried with AOD specified)</div><div>-0.055<span style="white-space:pre"> </span>- mean target elevation above sea level [km]</div><div>-1000<span style="white-space:pre"> </span>- sensor height</div><div>166<span style="white-space:pre"> </span>- Sentinel2A Blue band B2 (440nm - 535nm)</div></div><div><br></div><div><div>----------------------------------------</div></div><div>Command:<br></div><div>i.atcorr input=test_B02@p_Sentinel4Nature_S2_Oslo range=1,28000 elevation=dem_10m_25833@p_Sentinel4Nature_S2_Oslo parameters=/home/<a href="http://NINA.NO/zofie.cimburova/Sentinel4Nature/DATA/6s.txt">NINA.NO/zofie.cimburova/Sentinel4Nature/DATA/6s.txt</a> output=test_B02_atcorr<br></div><div><div>>Atmospheric correction...</div><div>>Atmospheric correction complete.</div></div><div><br></div><div>(I am not sure about the range parameter, tried with 0,255 too. The DEM contains no NULLs. Also tried running with -r and -a flags.)</div><div><br></div><div><div>----------------------------------------</div></div><div>Output:</div><div><div><a href="http://r.info">r.info</a> map=test_B02_atcorr@p_Sentinel4Nature_S2_Oslo </div><div> +----------------------------------------------------------------------------+</div><div> | Map: test_B02_atcorr@p_Sentinel4N Date: Mon Dec 18 13:10:14 2017 </div><div> | Mapset: p_Sentinel4Nature_S2_Oslo Login of Creator: zofie.cimburova </div><div> | Location: ETRS_33N </div><div> | DataBase: /data/grass </div><div> | Title: test_B02_atcorr2 </div><div> | Timestamp: none </div><div> |----------------------------------------------------------------------------|</div><div> | </div><div> | Type of Map: raster Number of Categories: 0 </div><div> | Data Type: FCELL </div><div> | Rows: 1001 </div><div> | Columns: 1001 </div><div> | Total Cells: 1002001 </div><div> | Projection: UTM (zone 33) </div><div> | N: 6653695 S: 6643685 Res: 10 </div><div> | E: 266505 W: 256495 Res: 10 </div><div> | Range of data: min = -nan max = -nan </div><div> | </div><div> | Data Description: </div><div> | generated by i.atcorr </div><div> | </div><div> | Comments: </div><div> | i.atcorr input="test_B02@p_Sentinel4Nature_S2_Oslo" range=1,28\ </div><div> | 000 elevation="dem_10m_25833@p_Sentinel4Nature_S2_Oslo" para\ </div><div> | meters="/home/<a href="http://NINA.NO/zofie.cimburova/Sentinel4Nature/DATA/6s.txt">NINA.NO/zofie.cimburova/Sentinel4Nature/DATA/6s.txt</a>" o\ </div><div> | utput="test_B02_atcorr2" rescale=0,255 </div><div> | </div><div> +----------------------------------------------------------------------------+</div></div><div><br></div><div><br></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Dec 15, 2017 at 5:12 PM, Žofie Cimburová <span dir="ltr"><<a href="mailto:zoficimburova@gmail.com" target="_blank">zoficimburova@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Dear Markus,<div>thanks for your reply, this is exactly what I need to know!</div><div><br></div><div>Best, Zofie</div></div><div class="gmail-m_8754325917693739443HOEnZb"><div class="gmail-m_8754325917693739443h5"><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Dec 15, 2017 at 5:09 PM, Markus Neteler <span dir="ltr"><<a href="mailto:neteler@osgeo.org" target="_blank">neteler@osgeo.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><span><p dir="ltr"><br>
On Dec 15, 2017 3:54 PM, "Žofie Cimburová" <<a href="mailto:zoficimburova@gmail.com" target="_blank">zoficimburova@gmail.com</a>> wrote:<br>
><br>
> Dear all,<br>
> I am trying to use i.atcorr (GRASS 7.4) to apply atmospheric corrections for Sentinel 2 data. The documentation provides a great help, but there are two points I am not sure about - <br>
><br>
> - I don't need the atmospheric correction to be applied to the whole scene, so I only imported a small clip of the scene to GRASS. What longitude and latitude shall I then specify in the 6S parameters?</p>
</span><p dir="ltr">I'd use the center coordinates of the clipped area.</p><span>
<p dir="ltr">> Or is it necessary to apply the corrections to the entire scene?<br></p>
</span><p dir="ltr">No since it is a pixel based algorithm.</p><span>
<p dir="ltr">> - How can I estimate the value of visibility (aerosol model concentration)? </p>
</span><p dir="ltr">There are AERONET data online somewhere which might be the best choice.</p><span class="gmail-m_8754325917693739443m_-1653079962449999712HOEnZb"><font color="#888888">
<p dir="ltr">Markus</p>
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