Re: [gdal-dev] Writing multi-bands vs multi-datasets

Even Rouault Thu, 14 Oct 2021 12:14:37 -0700


Le 14/10/2021 à 21:03, Joaquim Manuel Freire Luís a écrit :

Even,

There are some issues with this way.
My draft Julia function looks like bellow (tested with a MxNx7 array)but get this errors
julia> GMT.write_multiband(cube, "gd_cube.nc")

Warning 1: No 1D variable is indexed by dimension time
Warning 6: creation option '-co' is not formatted with the key=valueformat
Warning 6: creation option '-co' is not formatted with the key=valueformat
Warning 6: creation option '-co' is not formatted with the key=valueformat

I don't know the Julia bindings, but the error message seems to suggestyou can remove the "-co" element in your options[] array since itpresumably must only contain the "key=value" creation options, like inthe Python bindings

ERROR 1: netcdf error #-45 : NetCDF: Not a valid data type or_FillValue type mismatch .
at(C:\programs\compa_libs\gdal_GIT\gdal\frmts\netcdf\netcdfdataset.cpp,netCDFDataset::CreateCopy,9012)
ERROR 1: netcdf error #-49 : NetCDF: Variable not found .
at(C:\programs\compa_libs\gdal_GIT\gdal\frmts\netcdf\netcdfdataset.cpp,NCDFPutAttr,10454)
Warning 1: No 1D variable is indexed by dimension time
And indeed the “time” variable shows up filled with 7 zeros when Iopen the nc file that is nevertheless created.
Also checked with getmetadataitem(ds, "NETCDF_DIM_time_VALUES") thatthe "1,2,3,4,5,6,7" info was correctly set.

You need to surround the values of the _DEF and _VALUES items with { and} braces to indicate this is a list (this is the particular syntaxexpected by the netCDF driver)

I’s also strange the warnings about the “-co” options also becausethey were in fact taken into account. Omitting them creates a classicnc file.

function write_multiband(cube, fname::AbstractString, v=nothing;dim_name::String="time")


               nbands = size(cube,3)

               ds = gmt2gd(cube)

Gdal.setmetadataitem(ds, "NETCDF_DIM_EXTRA", dim_name)

Gdal.setmetadataitem(ds, "NETCDF_DIM_" * dim_name *"_DEF", "$(nbands),6")

Gdal.setmetadataitem(ds, "NETCDF_DIM_" * dim_name * "_VALUES","1,2,3,4,5,6,7")


Gdal.setmetadataitem(ds, dim_name * "#axis", string(dim_name[1]))

               crs = Gdal.getproj(cube, wkt=true)

               (crs != "" ) && Gdal.setproj!(ds, crs)

Gdal.unsafe_copy(ds, filename=fname, driver=getdriver("netCDF"),options=["-co", "FORMAT=NC4", "-co", "COMPRESS=DEFLATE", "-co","ZLEVEL=4"])


end

*From:*Even Rouault <even.roua...@spatialys.com>
*Sent:* Sunday, October 10, 2021 10:48 PM
*To:* Joaquim Manuel Freire Luís <jl...@ualg.pt>; gdal-dev@lists.osgeo.org
*Subject:* Re: [gdal-dev] Writing multi-bands vs multi-datasets

Joaquim,

https://github.com/OSGeo/gdal/pull/4634<https://github.com/OSGeo/gdal/pull/4634> should hopefully help


Even

Le 10/10/2021 à 22:26, Joaquim Manuel Freire Luís a écrit :

    Hi,

    I have a Julia version of gdal_translate (that ends up calling
    GDALDatasetRasterIOEx) that works in saving a MxNxP array, but not
    the way I wanted.

    It creates a multi-subdatasets file, whilst what I wished is to
    write a multi-band file.

    For example, the file written with this Julia function looks like
    below

    How can I write a multi-band instead of a multi-datasets?

    I’ve been looking at the docs of GDALDatasetRasterIOEx but can’t
    see any way of picking one or the other.

    Joaquim

    gdalinfo cube_rad.nc

    Driver: netCDF/Network Common Data Format

    Files: cube_rad.nc

    Size is 512, 512

    Metadata:

    NC_GLOBAL#Conventions=CF-1.5

      NC_GLOBAL#GDAL=GDAL 3.4.0dev, released 2021/99/99

    NC_GLOBAL#history=Sun Oct 10 13:01:06 2021: GDAL CreateCopy(
    cube_rad.nc, ... )

    Subdatasets:

    SUBDATASET_1_NAME=NETCDF:"cube_rad.nc":Band1

    SUBDATASET_1_DESC=[1567x1519] Band1 (32-bit floating-point)

    SUBDATASET_2_NAME=NETCDF:"cube_rad.nc":Band2

    SUBDATASET_2_DESC=[1567x1519] Band2 (32-bit floating-point)

    …

    Saving the same data (or similar) from a Matlab code that I wrote
    long ago to stack grids, shows

    gdalinfo evi_cube.nc

    Driver: netCDF/Network Common Data Format

    Files: evi_cube.nc

    Size is 37, 59

    Origin = (580140.000000000000000,4418550.000000000000000)

    Pixel Size = (30.000000000000000,-30.000000000000000)

    Metadata:

    …

    latitude#actual_range={4416795,4418535}

    latitude#long_name=latitude

    latitude#units=degrees_north

    longitude#actual_range={580155,581235}

    longitude#long_name=longitude

    longitude#units=degrees_east

    NC_GLOBAL#Conventions=COARDS

    NC_GLOBAL#description=File written from Matlab

    NC_GLOBAL#node_offset=0

    NC_GLOBAL#Source_Software=Mirone

      NC_GLOBAL#title=Grid created by Mirone

    NETCDF_DIM_EXTRA={time}

    NETCDF_DIM_time_DEF={67,6}

    
NETCDF_DIM_time_VALUES={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67}

    z#actual_range={-856.4703369140625,176.8457641601562}

      z#long_name=z

      z#units=unknown

    z#_FillValue=-nan(ind)

    Corner Coordinates:

    Upper Left  ( 580140.000, 4418550.000)

    Lower Left  ( 580140.000, 4416780.000)

    Upper Right ( 581250.000, 4418550.000)

    Lower Right ( 581250.000, 4416780.000)

    Center      ( 580695.000, 4417665.000)

    Band 1 Block=37x59 Type=Float32, ColorInterp=Undefined

      NoData Value=nan

      Unit Type: unknown

      Metadata:

    actual_range={-856.4703369140625,176.8457641601562}

        long_name=z

        NETCDF_DIM_time=1

        NETCDF_VARNAME=z

        units=unknown

    _FillValue=-nan(ind)

    Band 2 Block=37x59 Type=Float32, ColorInterp=Undefined

      NoData Value=nan

      Unit Type: unknown

      Metadata:

    actual_range={-856.4703369140625,176.8457641601562}

        long_name=z

        NETCDF_DIM_time=2

        NETCDF_VARNAME=z

        units=unknown

    _FillValue=-nan(ind)

    …



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