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<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">Thanks for clarification, Markus.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">So, what would a module that puts together an 6s input file (which is what Roberta is about to produce if I understood correctly) have to do with a visibility map then? Nothing, probably?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">Would visibility values in the 6s parameter file be overwritten if a AOD map is provided to i.atcorr?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">The i.atcorr manual[1] is not particularly clear on this…<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">In fact handling of visibility map is mentioned as a remaining documentation issue in the manual.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">Maybe something you could have a look at in your GSoC project, Roberta?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">Cheers<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">Stefan<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">1: https://grass.osgeo.org/grass75/manuals/i.atcorr.html<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> Markus Metz <markus.metz.giswork@gmail.com>
<br>
<b>Sent:</b> torsdag 28. juni 2018 14:09<br>
<b>To:</b> Stefan Blumentrath <Stefan.Blumentrath@nina.no><br>
<b>Cc:</b> Yann Chemin <dr.yann.chemin@gmail.com>; mlennert@club.worldonline.be; GRASS-dev <grass-dev@lists.osgeo.org>; Roberta Fagandini <robifagandini@gmail.com><br>
<b>Subject:</b> Re: [GRASS-dev] compile 6S library in GRASS<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><br>
<br>
On Thu, Jun 28, 2018 at 2:03 PM, Stefan Blumentrath <<a href="mailto:Stefan.Blumentrath@nina.no">Stefan.Blumentrath@nina.no</a>> wrote:<br>
><br>
> Just one quick follow up question regarding your wild guess:<br>
><br>
> <br>
><o:p></o:p></p>
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<p class="MsoNormal">> With a raster map option, the module would have to make assumptions on units / scale of values in the map (documented in the manual), so in the further process e.g. average or median could be extracted (r.univar) and fed to 6s input file,
right?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">no, i.atcorr accepts a visibility raster map as input, equivalent to aerosol optical depth at 550nm.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Note that internally i.atcorr converts AOD at 550nm to visibility with<o:p></o:p></p>
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<p class="MsoNormal">v = exp(-log(taer55 / 2.7628f) / 0.79902f);<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Markus M<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">><br>
> <br>
><br>
> Cheers<br>
><br>
> Stefan<br>
><br>
> <br>
><br>
> <br>
><br>
> From: grass-dev <<a href="mailto:grass-dev-bounces@lists.osgeo.org">grass-dev-bounces@lists.osgeo.org</a>> On Behalf Of Yann Chemin<br>
> Sent: torsdag 28. juni 2018 13:38<br>
> To: <a href="mailto:mlennert@club.worldonline.be">mlennert@club.worldonline.be</a><br>
> Cc: Markus Metz <<a href="mailto:markus.metz.giswork@gmail.com">markus.metz.giswork@gmail.com</a>>; GRASS-dev <<a href="mailto:grass-dev@lists.osgeo.org">grass-dev@lists.osgeo.org</a>>; Roberta Fagandini <<a href="mailto:robifagandini@gmail.com">robifagandini@gmail.com</a>><br>
> Subject: Re: [GRASS-dev] compile 6S library in GRASS<br>
><br>
> <br>
><br>
> a wild guess: specify a raster input option for AOT (alongside other options), let user find its image source and use it.<br>
><br>
> <br>
><br>
> Very limited requirement for the GSoC student, most latitude for the the modules user.<br>
><br>
> <br>
><br>
> ----------<br>
> Dr. Yann Chemin<br>
><br>
> Freelancer<br>
><br>
> +33 7 83 85 5234<br>
><br>
> 3 Toulmelin, 56400 Plumergat, FR<br>
><br>
> <a href="https://www.paypal.me/yannchemin">https://www.paypal.me/yannchemin</a><br>
><br>
> <br>
><br>
> <br>
><br>
> On Thu, 28 Jun 2018 at 13:35, Moritz Lennert <<a href="mailto:mlennert@club.worldonline.be">mlennert@club.worldonline.be</a>> wrote:<br>
><br>
> On 28/06/18 12:17, Roberta Fagandini wrote:<br>
> > I'm not an expert in MODIS data so if someone wants to give<br>
> > suggestions about how to retrieve the AOT from these data, I will<br>
> > definitely add this option too.<br>
><br>
> I'm not an expert, and MarkusM can probably provide you with more info,<br>
> but you can already see <a href="https://lpdaac.usgs.gov/node/1265">https://lpdaac.usgs.gov/node/1265</a>.<br>
><br>
> Moritz<br>
><br>
><br>
> _______________________________________________<br>
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