[gdal-dev] Aggregate bands

Siebe Bosch siebe at hydroconsult.nl
Fri Jun 14 03:40:06 PDT 2013


Hi List,

The question was originally mine. Thanks to Paul for posting it.
Here's what I did (calling GDAL tools from VB.NET):

 1. Warping the NetCDF-file to match my desired co-ordinate system and
    crop the image.

    outputFile = OutputDir & "\" & Str(OrderNum).Trim & "_NSL_" &
    Str(i).Trim & ".nc"
    myArgs = " -of NetCDF -dstnodata -999 -te " & Xmin & " " & Ymin & "
    " & Xmax & " " & Ymax & "  -tr 1000 1000 -s_srs " & Chr(34) &
    "+proj=stere +x_0=0 +y_0=0 +lat_0=90 +lon_0=0 +lat_ts=60 +a=6378.388
    +b=6356.906" & Chr(34) & " -t_srs " & Chr(34) & "EPSG:28992" &
    Chr(34) & " " & myPath & " " & outputFile
    ProcessCollection.Add(Process.Start(GDALToolsDir &
    "\bin\gdalwarp.exe", myArgs))

 2. Translating the 24 bands to .ASC

    outputFile = myPath.Replace(".nc", ".asc")
    myArgs = "-of AAIGrid -sds " & myPath & " " & outputFile  'exports
    all 24 subdatasets
    ProcessCollection.Add(Process.Start(GDALToolsDir &
    "\bin\gdal_translate.exe", myArgs))


Now this results in 24 ASC rasters: outputFile.asc1, outputFile.asc2, 
outputFile.asc3 etc. through outputFile.asc24.

By itself this is absolutely great because it gives me access to each band.
My question however is still: how can I (1.) aggregate the values for 
all 24 bands into one band and (2.) write it to an  .ASC

Thanks,
Siebe













On 14-06-13 08:04, Paul Meems wrote:
> Hi Even,
>
> I've just tried and I get this result:
> Warning 1: dimension #2 (x) is not a Longitude/X dimension.
> Warning 1: dimension #1 (y) is not a Latitude/Y dimension.
> Input file size is 257, 329
> ERROR 6: AAIG driver doesn't support 24 bands.  Must be 1 band.
>
> So you are right, it doesn't work.
>
> I don't need an ASCII grid, a different format is also OK. But I do 
> need all bands combined/aggregated.
> Do you have a different suggestion?
>
> Or should I read (using Python or similar) each band/pixel and manual 
> aggregate them?
>
> Thanks,
>
>
> Paul
>
> *Paul Meems *
> Release manager, configuration manager
> and forum moderator of MapWindow GIS.
> www.mapwindow.org <http://www.mapwindow.org/>
>
> Owner of MapWindow.nl - Support for
> Dutch speaking users.
> www.mapwindow.nl <http://www.mapwindow.nl/>
>
> *
> *
>
>
>
> 2013/6/13 Even Rouault <even.rouault at mines-paris.org 
> <mailto:even.rouault at mines-paris.org>>
>
>     Le jeudi 13 juin 2013 15:54:42, Etienne Tourigny a écrit :
>     > that should be a simple as
>     >
>     > gdal_translate -of AAIGrid in.nc <http://in.nc> out.asc
>
>     Except that AAIGrid only supports 1-band datasets. I can't think
>     of a ASCII
>     based format that supports multi-band datasets.
>
>     >
>     > On Thu, Jun 13, 2013 at 8:32 AM, Paul Meems
>     <bontepaarden at gmail.com <mailto:bontepaarden at gmail.com>> wrote:
>     > > Hi list,
>     > >
>     > > I have a netCDF file with 24 bands.
>     > > I want to create a new (ASCII) grid with the bands aggregated.
>     > > Is this possible using the gdal tools or with an existing
>     python script?
>     > >
>     > > Thanks,
>     > >
>     > > Paul
>     > >
>     > > _______________________________________________
>     > > gdal-dev mailing list
>     > > gdal-dev at lists.osgeo.org <mailto:gdal-dev at lists.osgeo.org>
>     > > http://lists.osgeo.org/mailman/listinfo/gdal-dev
>
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>
>
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