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<span style="font-size: 12pt;">Hi Markus and </span><span style="font-family: Calibri, sans-serif; font-size: 12pt;">Žofie,</span></p>
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<span style="font-family: Calibri, sans-serif; font-size: 12pt;">thank you for your hints! </span></p>
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<span style="font-family: Calibri, sans-serif; font-size: 14.6667px;"><span style="font-size: 12pt;">I tested i.atcorr with </span><span><span style="font-size: 12pt;">range=1,10000 and </span><span><span style="font-size: 12pt;">rescale=1,10000. In this way, value
10000 is assigned to all those pixels with reflectance greater than 10000 in the not-corrected image band (</span><span style="font-family: Calibri, Helvetica, sans-serif, EmojiFont, "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols; font-size: 12pt;">I'm
using a blue band with min=1 and max= </span><span style="font-family: Calibri, Helvetica, sans-serif, EmojiFont, "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols; font-size: 12pt;">21604</span><span style="font-size: 12pt;">).
If I set <span>range=1,21604 and rescale<span>=1,10000 in this case, the output is an image with values ranging from 1 to 10000 (because of the rescale parameter) but all the pixels with reflectance > 10000 <span>in the not-corrected image band have different
values near 10000 and proportionally rescaled but not rigidly set to 10000.</span></span></span></span></span></span></span></p>
<p style="font-family: Calibri, Helvetica, sans-serif, EmojiFont, "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols; margin-top: 0px; margin-bottom: 0px;">
<span style="font-family: Calibri, sans-serif; font-size: 14.6667px;"><span><span><span style="font-size: 12pt;"><span><span><span>Just to be clearer, here some examples querying some pixels of the images :</span></span></span></span></span></span></span></p>
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<span style="font-family: Calibri, sans-serif; font-size: 14.6667px;"><span><span><span style="font-size: 12pt;"><span><span><span>#B02_not_corrected (original blue band)</span></span></span></span></span></span></span></p>
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<span style="font-family: Calibri, sans-serif; font-size: 14.6667px;"><span><span><span style="font-size: 12pt;"><span><span><span><span>px1_value: 21604</span><br>
</span></span></span></span></span></span></span></p>
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<span style="font-family: Calibri, sans-serif; font-size: 14.6667px;"><span><span><span style="font-size: 12pt;"><span><span><span><span><span><span>px2_</span>value: 17869</span><br>
</span></span></span></span></span></span></span></span></p>
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<span style="font-family: Calibri, sans-serif; font-size: 14.6667px;"><span><span><span style="font-size: 12pt;"><span><span><span><span><span><span>px3_value: 18500</span><b><br>
</b></span></span></span></span></span></span></span></span></span></p>
<p style="margin-top: 0px; margin-bottom: 0px;"><font face="Calibri, sans-serif"><span>#B02_range_rescale_<span>1,10000 (i.atcorr output
<span>with range=1,10000 and rescale=1,10000</span>)</span></span></font></p>
<span><span>px1_</span>value: 10000</span>
<p style="margin-top: 0px; margin-bottom: 0px;"><font face="Calibri, sans-serif"><span><span><span></span><span><span>px2_</span>value: 10000</span><br>
</span></span></font></p>
<p style="margin-top: 0px; margin-bottom: 0px;"><font face="Calibri, sans-serif"><span><span><span><span style="font-family: Calibri, sans-serif; font-size: 16px;">px3_</span><span style="font-family: Calibri, sans-serif; font-size: 16px;">value: 10000</span><br>
</span></span></span></font></p>
<p style="margin-top: 0px; margin-bottom: 0px;"><font face="Calibri, sans-serif"><span><span><span style="font-family: Calibri, sans-serif; font-size: 16px;">#B02_range1,21604_rescale</span><span style="font-family: Calibri, sans-serif; font-size: 16px;">1,10000<span> (i.atcorr
output with <span style="font-family: Calibri, sans-serif; font-size: 16px;">range=1,21604 and rescale</span><span style="font-family: Calibri, sans-serif; font-size: 16px;">=1,10000</span>)</span></span><br>
</span></span></font></p>
<span><span><span><span style="font-family: Calibri, Helvetica, sans-serif, EmojiFont, "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols; font-size: 16px;"><span>px1_</span>value: 10000</span></span></span></span><br>
<span><span>px2_</span>value: 9055</span></div>
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<span><span>px3_</span>value: 9352</span></div>
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Therefore the meaning of the range parameter is still not so clear to me. Do you have other information about it and how it works?</div>
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Thank you for your help!</div>
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Roberta</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>Da:</b> Žofie Cimburová <zoficimburova@gmail.com><br>
<b>Inviato:</b> venerdě 9 febbraio 2018 21:01<br>
<b>A:</b> roberta fagandini<br>
<b>Cc:</b> grass-user@lists.osgeo.org<br>
<b>Oggetto:</b> Re: [GRASS-user] i.atcorr range and rescale parameters for Sentinel 2 images</font>
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<div dir="ltr">Hi Roberta,<br>
<div class="x_gmail_extra"><br>
<div class="x_gmail_quote">On Thu, Feb 8, 2018 at 8:54 PM, roberta fagandini <span dir="ltr">
<<a href="mailto:robifagandini@hotmail.it" target="_blank">robifagandini@hotmail.it</a>></span> wrote:<br>
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<p style="margin-top:0; margin-bottom:0">Hi all,</p>
<p style="margin-top:0; margin-bottom:0">I'm testing i.atcorr (grass 7.4) with Sentinel 2A images and i have some trouble defining the right values for range and rescale parameters. I read in other posts and lists that the suggested value for both range and
rescale is '0,10000' while in other posts someone else suggests to use min and max values (from
<a href="http://r.info" target="_blank">r.info</a>) for range and '1,10000' or '0, 10000' for rescale.</p>
<p style="margin-top:0; margin-bottom:0">It's not clear to me the right meaning of these parameters and thus the most correct values to be used.</p>
<p style="margin-top:0; margin-bottom:0">Can anyone better explain me the meaning of these two parameters?
<br>
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<div>When I was running i.atcorr for Sentinel2 data, I used range=1,10000 (i.e. the min/max theoretical values the input data can reach).
<br>
As for rescale, this in my understanding just sets what the output range of the reflectances will be. So you can use for example 1-255, 0-1, 1-10000, whatever suits best to your further analysis. Relatively, the result will be identical.<br>
<br>
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<div>Hope that helps a bit!<br>
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<div>Zofie<br>
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<p style="margin-top:0; margin-bottom:0"></p>
<p style="margin-top:0; margin-bottom:0">I tested all the values suggested in other posts but I can't understand what they exactly do.</p>
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<p style="margin-top:0; margin-bottom:0">Thank you in advance for your help!</p>
<span class="x_HOEnZb"><font color="#888888">
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<p style="margin-top:0; margin-bottom:0">Roberta<br>
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