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 > [email protected]http://lists.osgeo.org/mailman/listinfo/gdal-dev > > > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev >
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