Dear all: The problem I was facing has been solved. I detected that the problem was with the band number '0'. Solution is: the band number starts from '1'.
But, the gdal documentation says that the default band number is '0'. http://www.gdal.org/gdal_calc.html The documentation should be corrected, I think. The default band number is '1'. Thanks. cleo On Wed, Jul 30, 2014 at 11:15 AM, Jeremy Palmer <[email protected]> wrote: > Hi Cleo, > > > > Just been dealing with this type of issue. > > > > It’s likely that the byte datatype is overflowing. > > > > Try something like: > > > > --calc "(A.astype(int)-B.astype(int))/(A.astype(int)+B.astype(int))" > > > > Actually you might only need to cast one of the bands from byte to int, so > the syntax could be: > > > > --calc "(A.astype(int)-B A.astype(int)+B)" > > > > Cheers > Jeremy > > > > *From:* [email protected] [mailto: > [email protected]] *On Behalf Of *Cleo Drakos > *Sent:* Wednesday, 30 July 2014 2:06 p.m. > *To:* Vincent Schut > *Cc:* gdal-dev > *Subject:* Re: [gdal-dev] Does gdal_calc.py not calculate arithmetic with > in the same file? > > > > Even if I converted the input file into Float 32 at first, the resulted > image is still totally black. > > > cleo > > > > On Tue, Jul 29, 2014 at 11:20 PM, Vincent Schut <[email protected]> > wrote: > > On 07/29/2014 04:04 PM, Cleo Drakos wrote: > > Thanks for your response. > > I tried the followings: > > > > gcalc = 'C:\\Users\\cleo\\Documents\\gdalpys\\gdal_calc.py' > > ##I produced second file (b)as the copy of first(a) > > a = 'D:\\a.tif' > > b = 'D:\\b.tif' > > outfile = 'D:\\result.tif' > > expr = '(A-B)/(A+B)' > > > subprocess.call([sys.executable,gcalc,'-A',a,'--A_band','1','-B',b,'--B_band','0','--outfile',outfile,\ > > '--calc',expr,'--type','Float32','--format','ENVI'],shell=True) > > a,b,outfile = None, None,None > > > > Unfortunately, resulted file is completely black. > > > > I hope someone can help me. > > > > 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. > > Best, > Vincent. > > > > > > > On Tue, Jul 29, 2014 at 10:37 PM, Etienne Tourigny < > [email protected]> wrote: > > I am not sure, but you can do the following to make sure: > > > > cp infile infile2 > > gdal_calc.py -A infile --A_band 1 -B infile2 --B_band 0 --outfile outfile > --calc "(A-B)/(A+B)" > > > > Also, perhaps the extra comma in your command might be to blame "-B > infile," > > > > Etienne > > > > On Tue, Jul 29, 2014 at 3:46 AM, Cleo Drakos <[email protected]> > wrote: > > Hi GDAL Developers, > > I have one GeoTIFF file with 2 bands. The data type is Byte. I want to > calculate (Band2-Band1)/(Band2+Band1). > > But the following command provided a dark image: > > gdal_calc.py -A infile --A_band 1 -B infile, --B_band 0 --outfile outfile > --calc "(A-B)/(A+B)" > > Does gdal_calc.py not calculate arithmetic with in the same file? > > Thanks for your time. > > cleo > > > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev > > > > _______________________________________________ > > gdal-dev mailing list > > [email protected] > > http://lists.osgeo.org/mailman/listinfo/gdal-dev > > > > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev > > > > ------------------------------ > This message contains information, which may be in confidence and may be > subject to legal privilege. If you are not the intended recipient, you must > not peruse, use, disseminate, distribute or copy this message. If you have > received this message in error, please notify us immediately (Phone 0800 > 665 463 or [email protected]) and destroy the original message. LINZ > accepts no responsibility for changes to this email, or for any > attachments, after its transmission from LINZ. Thank You. >
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