[gdal-dev] GDAL multi bands files conversion to NetCDF

Wed Jul 18 11:57:18 PDT 2018

Thanks for your answer Even,

I was looking at a one step solution because I wanted MapServer to
output the NetCDF with different bands instead of individual
Subdatasets... I should have mentioned that first in my question.

Basically, I have layers in MapServer which are served in WCS. Since we
can't use TIME= in WCS 2.0.1 and that I need to be able to output time
range and lists in a single WCS request, I'm using the band names and
the RANGESUBSET= feature to request multiple bands in the NetCDF output
format.

But the MapServer output NetCDF have many SUBDATASETs instead of many
bands... I was hoping to be able to add a FORMATOPTION in the NetCDF
OUTPUTFORMAT in MapServer to make it work, but from your answer I get
that it's not possible.

Thanks !

LP

On 07/18/2018 06:44 PM, Even Rouault wrote:
> Louis Philippe
>
> there's no one single step to do that, but you can do that in 2 steps:
>
> - use gdal_translate -sds to export all the subdatasets in separate tif files
> - use gdal_merge.py -separate to combine them in a single tif file (provided 
> they have same resolution, extent, cordinate system), which seems to be your 
> case here
>
> Even
>
>> Hi everyone!
>>
>> I have s question regarding the conversion of a multiband file (like
>> GeoTIFF) to NetCDF.
>>
>> First my observations:
>>
>> I used gdal_translate to convert a Geotiff to NetCDF:
>>
>> gdal_translate -of input.tif result.nc
>>
>> The gdalinfo result is:
>>
>> Driver: netCDF/Network Common Data Format
>> Files: result.nc
>> Size is 512, 512
>> Coordinate System is `'
>> Metadata:
>>   NC_GLOBAL#Conventions=CF-1.5
>>   NC_GLOBAL#GDAL=GDAL 1.10.0, released 2013/04/24
>>   NC_GLOBAL#GDAL_AREA_OR_POINT=Area
>>   NC_GLOBAL#history=Wed Jul 18 15:33:16 2018: GDAL CreateCopy( result.nc,
>> ... ) Subdatasets:
>>   SUBDATASET_1_NAME=NETCDF:"result.nc":Band1
>>   SUBDATASET_1_DESC=[1500x1650] Band1 (32-bit floating-point)
>>   SUBDATASET_2_NAME=NETCDF:"result.nc":Band2
>>   SUBDATASET_2_DESC=[1500x1650] Band2 (32-bit floating-point)
>>   SUBDATASET_3_NAME=NETCDF:"result.nc":Band3
>>   SUBDATASET_3_DESC=[1500x1650] Band3 (32-bit floating-point)
>>   SUBDATASET_4_NAME=NETCDF:"result.nc":Band4
>>   SUBDATASET_4_DESC=[1500x1650] Band4 (32-bit floating-point)
>>   SUBDATASET_5_NAME=NETCDF:"result.nc":Band5
>>   SUBDATASET_5_DESC=[1500x1650] Band5 (32-bit floating-point)
>> Corner Coordinates:
>> Upper Left  (    0.0,    0.0)
>> Lower Left  (    0.0,  512.0)
>> Upper Right (  512.0,    0.0)
>> Lower Right (  512.0,  512.0)
>> Center      (  256.0,  256.0)
>>
>> As you can see, the different bands are written in different SUBDATASET. I
>> would like the output to be only different bands, not different datasets. I
>> don't think I saw a creation option that could do that...
>>
>> I would like something like:
>>
>> Driver: netCDF/Network Common Data Format
>> Files: output.nc
>> Size is 1068, 510
>> Coordinate System is `'
>> Origin = (-140.999964377091317,83.499994903744323)
>> Pixel Size = (0.083333295198278,-0.083333313348017)
>> Metadata:
>>   lat#axis=Y
>>   lat#long_name=latitude
>>   lat#standard_name=latitude
>>   lat#units=degrees_north
>>   lon#axis=X
>>   lon#long_name=longitude
>>   lon#standard_name=longitude
>>   lon#units=degrees_east
>> ...Some metadata...
>> Corner Coordinates:
>> Upper Left  (-140.9999644,  83.4999949)
>> Lower Left  (-140.9999644,  41.0000051)
>> Upper Right ( -52.0000051,  83.4999949)
>> Lower Right ( -52.0000051,  41.0000051)
>> Center      ( -96.4999847,  62.2500000)
>> Band 1 Block=1068x1 Type=Float32, ColorInterp=Undefined
>>     Computed Min/Max=-29.841,11.720
>>   NoData Value=-99
>>   Metadata:
>>     long_name=Autumn mean temperature
>>     missing_value=-99
>>     NETCDF_DIM_time=17093376
>>     NETCDF_VARNAME=tm_son
>>     _FillValue=-99
>> Band 2 Block=1068x1 Type=Float32, ColorInterp=Undefined
>>     Computed Min/Max=-30.198,11.576
>>   NoData Value=-99
>>   Metadata:
>>     long_name=Autumn mean temperature
>>     missing_value=-99
>>     NETCDF_DIM_time=17102136
>>     NETCDF_VARNAME=tm_son
>>     _FillValue=-99
>> Band 3 Block=1068x1 Type=Float32, ColorInterp=Undefined
>>     Computed Min/Max=-30.479,11.854
>>   NoData Value=-99
>>   Metadata:
>>     long_name=Autumn mean temperature
>>     missing_value=-99
>>     NETCDF_DIM_time=17110920
>>     NETCDF_VARNAME=tm_son
>>     _FillValue=-99
>>
>>
>> Is there anything I missed ? Can you think of another way to do that ?
>>
>> Thanks a lot!
>>
>> LP
>

-- 
Louis-Philippe Rousseau Lambert, B.Sc.
Géomaticien / Geomatician
Section des Données, Performances et Standards
Data, Performance and Standards Section
Service Météorologique du Canada
Meteorological Service of Canada
Environnement et Changement Climatique Canada
Environment and Climate Change Canada
louis-philippe.rousseaulambert2 at canada.ca
(514) 421-5045