<div dir="ltr"><p class="MsoNormal" style="font-size:13px;font-family:arial,sans-serif"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">Hi Jeremy</span></p><p class="MsoNormal" style="font-size:13px;font-family:arial,sans-serif">
<span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><br></span></p><p class="MsoNormal" style="font-size:13px;font-family:arial,sans-serif"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">Your idea is grateful.</span></p>
<p class="MsoNormal" style="font-size:13px;font-family:arial,sans-serif"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><br></span></p><p class="MsoNormal" style="font-size:13px;font-family:arial,sans-serif">
<span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">The following code worked for me:</span></p><p class="MsoNormal" style="font-size:13px;font-family:arial,sans-serif"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">--calc "(A.astype(float32)-B A.astype(float32)+B)"</span></p>
</div><div class="gmail_extra"><br clear="all"><div><div dir="ltr">cleo</div></div>
<br><br><div class="gmail_quote">On Wed, Jul 30, 2014 at 11:15 AM, Jeremy Palmer <span dir="ltr"><<a href="mailto:JPalmer@linz.govt.nz" target="_blank">JPalmer@linz.govt.nz</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Hi Cleo,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Just been dealing with this type of issue.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">It’s likely that the byte datatype is overflowing.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Try something like:<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">--calc "(A.astype(int)-B.astype(int))/(A.astype(int)+B.astype(int))"<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Actually you might only need to cast one of the bands from byte to int, so the syntax could be:<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">--calc "(A.astype(int)-B A.astype(int)+B)"<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Cheers<br>
Jeremy<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:gdal-dev-bounces@lists.osgeo.org" target="_blank">gdal-dev-bounces@lists.osgeo.org</a> [mailto:<a href="mailto:gdal-dev-bounces@lists.osgeo.org" target="_blank">gdal-dev-bounces@lists.osgeo.org</a>]
<b>On Behalf Of </b>Cleo Drakos<br>
<b>Sent:</b> Wednesday, 30 July 2014 2:06 p.m.<br>
<b>To:</b> Vincent Schut<br>
<b>Cc:</b> gdal-dev<br>
<b>Subject:</b> Re: [gdal-dev] Does gdal_calc.py not calculate arithmetic with in the same file?<u></u><u></u></span></p><div><div class="h5">
<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Even if I converted the input file into Float 32 at first, the resulted image is still totally black.<u></u><u></u></p>
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<p class="MsoNormal"><br clear="all">
<u></u><u></u></p>
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<p class="MsoNormal">cleo<u></u><u></u></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><u></u> <u></u></p>
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<p class="MsoNormal">On Tue, Jul 29, 2014 at 11:20 PM, Vincent Schut <<a href="mailto:schut@sarvision.nl" target="_blank">schut@sarvision.nl</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal">On 07/29/2014 04:04 PM, Cleo Drakos wrote:<br>
<br>
<u></u><u></u></p>
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<p class="MsoNormal">Thanks for your response. <u></u><u></u></p>
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<p class="MsoNormal">I tried the followings:<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">gcalc = 'C:\\Users\\cleo\\Documents\\gdalpys\\gdal_calc.py'<u></u><u></u></p>
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<p class="MsoNormal">##I produced second file (b)as the copy of first(a)<u></u><u></u></p>
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<p class="MsoNormal">a = 'D:\\a.tif'<u></u><u></u></p>
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<p class="MsoNormal">b = 'D:\\b.tif'<u></u><u></u></p>
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<p class="MsoNormal">outfile = 'D:\\result.tif'<u></u><u></u></p>
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<p class="MsoNormal">expr = '(A-B)/(A+B)'<u></u><u></u></p>
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<p class="MsoNormal">subprocess.call([sys.executable,gcalc,'-A',a,'--A_band','1','-B',b,'--B_band','0','--outfile',outfile,\<u></u><u></u></p>
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<p class="MsoNormal"> '--calc',expr,'--type','Float32','--format','ENVI'],shell=True) <u></u><u></u></p>
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<p class="MsoNormal">a,b,outfile = None, None,None<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Unfortunately, resulted file is completely black.<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">I hope someone can help me.<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">I don't use gdal_calc myself, but I suppose the problem is the byte datatype. I would try to convert the input data to float32 first (use gdal_translate -ot Float32) and try again.<br>
<br>
Best,<br>
Vincent.<u></u><u></u></p>
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<p class="MsoNormal"><br>
<br>
<br>
<u></u><u></u></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><u></u> <u></u></p>
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<p class="MsoNormal">On Tue, Jul 29, 2014 at 10:37 PM, Etienne Tourigny <<a href="mailto:etourigny.dev@gmail.com" target="_blank">etourigny.dev@gmail.com</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal">I am not sure, but you can do the following to make sure: <u></u>
<u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">cp infile infile2<u></u><u></u></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">gdal_calc.py -A infile --A_band 1 -B infile2 --B_band 0 --outfile outfile --calc "(A-B)/(A+B)" </span><u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">Also, perhaps the extra comma in your command might be to blame "</span><span style="font-family:"Arial","sans-serif"">-B infile,"</span><u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal"><span style="font-family:"Arial","sans-serif"">Etienne</span><u></u><u></u></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><u></u> <u></u></p>
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<p class="MsoNormal">On Tue, Jul 29, 2014 at 3:46 AM, Cleo Drakos <<a href="mailto:cleo21drakos@gmail.com" target="_blank">cleo21drakos@gmail.com</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal">Hi GDAL Developers,<br>
<br>
I have one GeoTIFF file with 2 bands. The data type is Byte. I want to calculate (Band2-Band1)/(Band2+Band1).<br>
<br>
But the following command provided a dark image:<br>
<br>
gdal_calc.py -A infile --A_band 1 -B infile, --B_band 0 --outfile outfile --calc "(A-B)/(A+B)"
<br>
<br>
Does gdal_calc.py not calculate arithmetic with in the same file?<br>
<br>
Thanks for your time.<span style="color:#888888"><br>
<br>
cleo</span><u></u><u></u></p>
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