[gdal-dev] NetCDF projection help
Even Rouault
even.rouault at spatialys.com
Tue Jul 12 05:13:40 PDT 2022
Brendan,
You need to warp the raster using the geolocation array formed by the
lon and lat variable:
gdalwarp -overwrite -geoloc CORDEX_subarea_O3.nc out.tif
(possibly using -t_srs EPSG:XXXX to indicate a more relevant SRS than
EPSG:4326)
> why is the GDAL netcdf driver not properly creating an affine?
It can only report an affine geotransform matrix when the lat and lon
arrays are 1D, and have regular spacing. Here they are 2D and
potentially express a "random" georeferencing, hence they are reported
as a geolocation array.
Even
Le 12/07/2022 à 13:38, DeTracey, Brendan a écrit :
> Hi,
>
> I have been "gifted" a netcdf raster that I must vectorize. When I load the raster into QGIS the coordinates are not correct. I believe that QGIS uses GDAL drivers. I have included a download link to the file, a ncdump -h, and gdalinfo output, all at the bottom of this message. The raster is on the CORDEX arctic grid [https://cordex.org/domains/region-11-arctic/], a rotated pole projection with the pole at 0.0E, 6.55N and a Top Left Corner of 337.12E, 33.88N. My raster is double the resolution described in the specification. The raster covers the arctic and is a binary mask for Baffin Bay. The raster includes the lat and lon, but not the rotated projection lat and lon.
>
> What do I need to do to get QGIS to properly load the coordinates for this raster? (The raster is too coarse for my needs. My plan is to use QGIS to manually draw a shapefile of the raster boundaries.) Why is the GDAL netcdf driver not properly creating an affine? Is it because the raster spans the pole?
>
> Thanks so much,
> Brendan
>
> https://file.io/3ITCNwX0fg3s : CORDEX_subarea_O3.nc : 1MB
>
> $ ncdump -h CORDEX_subarea_O3.nc
> netcdf CORDEX_subarea_O3 {
> dimensions:
> x = 232 ;
> y = 266 ;
> variables:
> double lon(y, x) ;
> lon:standard_name = "longitude" ;
> lon:long_name = "longitude" ;
> lon:units = "degrees_east" ;
> lon:_CoordinateAxisType = "Lon" ;
> double lat(y, x) ;
> lat:standard_name = "latitude" ;
> lat:long_name = "latitude" ;
> lat:units = "degrees_north" ;
> lat:_CoordinateAxisType = "Lat" ;
> double mmask(y, x) ;
> mmask:coordinates = "lon lat" ;
> mmask:_FillValue = -9.e+33 ;
> mmask:missing_value = -9.e+33 ;
>
> // global attributes:
> :CDI = "Climate Data Interface version 1.6.8 (http://mpimet.mpg.de/cdi)" ;
> :Conventions = "CF-1.4" ;
> :history = "Mon Apr 20 17:37:28 2020: cdo eqc,3 All_subareas_CORDEX_final.nc CORDEX_subarea_O3.nc\n",
> "Sat Apr 11 22:10:21 2020: cdo add jonn.nc jlnn.nc jann.nc\n",
> "Sat Apr 11 21:55:59 2020: cdo sub latest_5.nc jln.nc jon.nc\n",
> "Sat Apr 11 17:29:06 2020: cdo add jos.nc Land_subareas_new.nc All_subareas_CORDEX_reedited.nc\n",
> "Sat Apr 11 17:22:45 2020: cdo sub All_subareas_CORDEX_edited.nc j.nc jos.nc\n",
> "Tue Apr 07 15:58:18 2020: cdo add jon.nc EPA_Arctic_bioregions_CORDEX_land_masked_edited.nc All_subareas_CORDEX_edited.nc\n",
> "Tue Apr 07 15:19:29 2020: cdo sub All_subareas_CORDEX_best.nc jl.nc jo.nc_\n",
> "Tue Apr 07 00:58:57 2020: cdo remapnn,ARC-22_sample_grid.nc All_subareas_.25deg.nc j.nc\n",
> "Tue Apr 07 00:48:41 2020: cdo add NAA_subareas_.25deg.nc EPA_Arctic_bioregions_.25degx-1.nc All_subareas_.25deg.nc\n",
> "Tue Apr 07 00:48:01 2020: cdo mulc,-1 EPA_Arctic_bioregions_.25deg.nc EPA_Arctic_bioregions_.25degx-1.nc\n",
> "Mon Apr 06 17:20:07 2020: cdo add 4xAlaskan_Tundra_mask_l2_.25deg.nc jNSCff.nc jNSCA.nc\n",
> "Mon Apr 6 17:18:06 2020: /HOME/opt/package/nco/linux64/bin/ncap2 -s mask_array=int(mask_array) jNSCf.nc jNSCff.nc\n",
> "Mon Apr 6 17:17:29 2020: /HOME/opt/package/nco/linux64/bin/ncap2 -s where(mask_array > 3.) mask_array = 3. jNSCfl.nc jNSCf.nc\n",
> "Mon Apr 6 17:17:06 2020: /HOME/opt/package/nco/linux64/bin/ncap2 -s mask_array=float(mask_array) jNSC.nc jNSCfl.nc\n",
> "Mon Apr 06 16:38:46 2020: cdo add 3xArctic_Cordillera_mask_l2_.25deg.nc jNS.nc jNSC.nc\n",
> "Mon Apr 06 16:36:11 2020: cdo add Southern_Arctic_mask_l2_.25deg.nc 2xNorthern_Arctic_mask_l2_.25deg.nc jNS.nc\n",
> "Mon Apr 06 16:35:10 2020: cdo mulc,2 Northern_Arctic_mask_l2_.25deg.nc 2xNorthern_Arctic_mask_l2_.25deg.nc" ;
> :DOMAIN_number_total = 1 ;
> :DOMAIN_number = 0 ;
> :DOMAIN_dimensions_ids = 1, 2 ;
> :DOMAIN_size_global = 568, 400 ;
> :DOMAIN_size_local = 568, 400 ;
> :DOMAIN_position_first = 1, 1 ;
> :DOMAIN_position_last = 568, 400 ;
> :DOMAIN_halo_size_start = 0, 0 ;
> :DOMAIN_halo_size_end = 0, 0 ;
> :DOMAIN_type = "BOX" ;
> :history_of_appended_files = "Mon Oct 2 22:18:28 2017: Appended file mesh_zgr.nc had following \"history\" attribute:\n",
> "Mon Oct 2 22:18:08 2017: ncks -A mesh_hgr.nc mesh_zgr.nc\n",
> "" ;
> :NCO = "\"4.5.2\"" ;
> :CDO = "Climate Data Operators version 1.6.8rc2 (http://mpimet.mpg.de/cdo)" ;
> }
>
>
> $ gdalinfo CORDEX_subarea_O3.nc
> Warning 1: Recode from UTF-8 to CP_ACP failed with the error: "Invalid argument".
> Driver: netCDF/Network Common Data Format
> Files: CORDEX_subarea_O3.nc
> CORDEX_subarea_O3.nc.aux.xml
> Size is 232, 266
> Metadata:
> mmask#coordinates=lon lat
> mmask#missing_value=-9e+33
> mmask#_FillValue=-9e+33
> NC_GLOBAL#CDI=Climate Data Interface version 1.6.8 (http://mpimet.mpg.de/cdi)
> NC_GLOBAL#CDO=Climate Data Operators version 1.6.8rc2 (http://mpimet.mpg.de/cdo)
> NC_GLOBAL#Conventions=CF-1.4
> NC_GLOBAL#DOMAIN_dimensions_ids={1,2}
> NC_GLOBAL#DOMAIN_halo_size_end={0,0}
> NC_GLOBAL#DOMAIN_halo_size_start={0,0}
> NC_GLOBAL#DOMAIN_number=0
> NC_GLOBAL#DOMAIN_number_total=1
> NC_GLOBAL#DOMAIN_position_first={1,1}
> NC_GLOBAL#DOMAIN_position_last={568,400}
> NC_GLOBAL#DOMAIN_size_global={568,400}
> NC_GLOBAL#DOMAIN_size_local={568,400}
> NC_GLOBAL#DOMAIN_type=BOX
> NC_GLOBAL#history=Mon Apr 20 17:37:28 2020: cdo eqc,3 All_subareas_CORDEX_final.nc CORDEX_subarea_O3.nc
> Sat Apr 11 22:10:21 2020: cdo add jonn.nc jlnn.nc jann.nc
> Sat Apr 11 21:55:59 2020: cdo sub latest_5.nc jln.nc jon.nc
> Sat Apr 11 17:29:06 2020: cdo add jos.nc Land_subareas_new.nc All_subareas_CORDEX_reedited.nc
> Sat Apr 11 17:22:45 2020: cdo sub All_subareas_CORDEX_edited.nc j.nc jos.nc
> Tue Apr 07 15:58:18 2020: cdo add jon.nc EPA_Arctic_bioregions_CORDEX_land_masked_edited.nc All_subareas_CORDEX_edited.nc
> Tue Apr 07 15:19:29 2020: cdo sub All_subareas_CORDEX_best.nc jl.nc jo.nc_
> Tue Apr 07 00:58:57 2020: cdo remapnn,ARC-22_sample_grid.nc All_subareas_.25deg.nc j.nc
> Tue Apr 07 00:48:41 2020: cdo add NAA_subareas_.25deg.nc EPA_Arctic_bioregions_.25degx-1.nc All_subareas_.25deg.nc
> Tue Apr 07 00:48:01 2020: cdo mulc,-1 EPA_Arctic_bioregions_.25deg.nc EPA_Arctic_bioregions_.25degx-1.nc
> Mon Apr 06 17:20:07 2020: cdo add 4xAlaskan_Tundra_mask_l2_.25deg.nc jNSCff.nc jNSCA.nc
> Mon Apr 6 17:18:06 2020: /HOME/opt/package/nco/linux64/bin/ncap2 -s mask_array=int(mask_array) jNSCf.nc jNSCff.nc
> Mon Apr 6 17:17:29 2020: /HOME/opt/package/nco/linux64/bin/ncap2 -s where(mask_array > 3.) mask_array = 3. jNSCfl.nc jNSCf.nc
> Mon Apr 6 17:17:06 2020: /HOME/opt/package/nco/linux64/bin/ncap2 -s mask_array=float(mask_array) jNSC.nc jNSCfl.nc
> Mon Apr 06 16:38:46 2020: cdo add 3xArctic_Cordillera_mask_l2_.25deg.nc jNS.nc jNSC.nc
> Mon Apr 06 16:36:11 2020: cdo add Southern_Arctic_mask_l2_.25deg.nc 2xNorthern_Arctic_mask_l2_.25deg.nc jNS.nc
> Mon Apr 06 16:35:10 2020: cdo mulc,2 Northern_Arctic_mask_l2_.25deg.nc 2xNorthern_Arctic_mask_l2_.25deg.nc
> NC_GLOBAL#history_of_appended_files=Mon Oct 2 22:18:28 2017: Appended file mesh_zgr.nc had following "history" attribute:
> Mon Oct 2 22:18:08 2017: ncks -A mesh_hgr.nc mesh_zgr.nc
>
> NC_GLOBAL#NCO="4.5.2"
> Subdatasets:
> SUBDATASET_1_NAME=NETCDF:"CORDEX_subarea_O3.nc":lon
> SUBDATASET_1_DESC=[266x232] longitude (64-bit floating-point)
> SUBDATASET_2_NAME=NETCDF:"CORDEX_subarea_O3.nc":lat
> SUBDATASET_2_DESC=[266x232] latitude (64-bit floating-point)
> SUBDATASET_3_NAME=NETCDF:"CORDEX_subarea_O3.nc":mmask
> SUBDATASET_3_DESC=[266x232] mmask (64-bit floating-point)
> Geolocation:
> LINE_OFFSET=0
> LINE_STEP=1
> PIXEL_OFFSET=0
> PIXEL_STEP=1
> SRS=GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AXIS["Latitude",NORTH],AXIS["Longitude",EAST],AUTHORITY["EPSG","4326"]]
> X_BAND=1
> X_DATASET=NETCDF:"CORDEX_subarea_O3.nc":lon
> Y_BAND=1
> Y_DATASET=NETCDF:"CORDEX_subarea_O3.nc":lat
> Corner Coordinates:
> Upper Left ( 0.0, 0.0)
> Lower Left ( 0.0, 266.0)
> Upper Right ( 232.0, 0.0)
> Lower Right ( 232.0, 266.0)
> Center ( 116.0, 133.0)
> Band 1 Block=232x1 Type=Float64, ColorInterp=Undefined
> Min=0.000 Max=1.000
> Minimum=0.000, Maximum=1.000, Mean=0.021, StdDev=0.144
> NoData Value=-9.00000000000000009e+33
> Metadata:
> coordinates=lon lat
> missing_value=-9e+33
> NETCDF_VARNAME=mmask
> STATISTICS_MAXIMUM=1
> STATISTICS_MEAN=0.021243842364532
> STATISTICS_MINIMUM=0
> STATISTICS_STDDEV=0.14419619109437
> _FillValue=-9e+33
>
>
> ------------------------------------------
> Brendan DeTracey, VS 203/2-3
> brendan.detracey at dfo-mpo.gc.ca
>
> Ocean Monitoring and Observation Section | Section de surveillance et d'observation océanique /
> Ocean Modelling and Analysis Section | Section d'analyse et de modélisation
>
> Ocean and Ecosystem Sciences Division | Division des sciences de l'écosystème et de la mer
> Fisheries and Oceans Canada | Pêches et Oceans Canada
> Bedford Institute of Oceanography | Institut Océanographique de Bedford
> P.O. Box 1006, 1 Challenger Dr. | C.P.1006, 1 Challenger Dr.
> Dartmouth, N.S. Canada B2Y 4A2 | Dartmouth, N.-É., Canada B2Y 4A2
> Telephone | Téléphone 902-426-9727
> ------------------------------------------
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> ------------------------------------------
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