Hi Ivan, I think I reported an issue like this some time ago in the QGIS issue tracker:
https://issues.qgis.org/issues/20730 I think(!), but I hope some netcdf guru jumps in, that the crux is how you define/interpret your data: is the value valid in the center of the grid (like a raster) or is it on the vertices (more like a mesh). It is all about interpretation of a datamodel: is it a grid or a raster. If I understand correctly in a mesh (and netcdf) is much more possible then in a raster: triangular meshes, non-regular etc etc: https://docs.qgis.org/3.4/en/docs/user_manual/working_with_mesh/mesh_properties.html I'm not sure who should be responsible for 'correcting/transforming' this: a netcdf which is written as if the values are on (for example) the upper-left corner vertices, while you actually mean the value is in the center of a (grid)cell... For a simple rectangular mesh, this seems feasible on the client side (see panoply example in first link), but for non-regular meshes/netcdf's this seems impossible client side (well actually that is not a raster/grid anymore).. In your case I would think that the data is actually mend to be a grid... Not sure if this is helpfull, as said I hope some netcdf guru jumps in. Maybe I'm oversimplifying here... Regards, Richard Duivenvoorde On 31/10/2019 22.06, Ivan Lucena wrote: > > Hi Folks, > > I Downloaded NetCDF files > from http://land.copernicus.eu/global/products/ndvi and I am having > problems with the GeoTransform that the driver is getting. > > The image extents, as you can see in following gdalinfo report, goes > beyond the -180 and +180 longitude degrees (half resolution, half pixel) > but that's OK according to page 27 in the PDF documentation: > PROBAV-Products_User_Manual_v1.3.pdf > <https://earth.esa.int/documents/700255/1929094/PROBAV-Products_User_Manual_v1.3.pdf/fd5e30f4-5305-4d41-86aa-fab7b9568251> > > > But if I open that image on QGIS and overlay a vector (GADM from > gadm.org) or any other global layer it is clear that -180x80 should be > in the upper left corner of the image, not In the center. There is a > half pixel missing on the left and bottom of the image. This in in Fiji: > > > > The gdalinfo report shows that the crs:GeoTransform is -180.0000000000 > 0.0029761905 0.0 80.0000000000 0.0 -0.0029761905 but it seems like the > driver decided to take that to as center of the pixel based. Looking at > the NetCDF source I can see that there this possibility exists. > > Of course, I am not waiting for a solution. I just used gdal_translate > "- a_ullr" and fix that into the target format. It takes centuries to > converted that image to geotiff. But I am concerned that others might > get in trouble because of that. > > I tried to contact the data provider but did not received an answer yet. > > Does anybody has experience with that dataset and/or NetCDF that can > help figure out what is going on. It is a bug in the driver or an issue > with the data. > > Thanks, > > - > Ivan > > Here is the gdalinfo report: > > Don't worry about the warnings in regards to the pixel values. It is fine. > > $ gdalinfo netcdf:c_gls_NDVI300_201910110000_GLOBE_PROBAV_V1.0.1.nc > --debug on > GDAL_netCDF: driver detected file type=5, libnetcdf detected type=3 > Warning 1: NetCDF driver detected file type=5, but libnetcdf detected > type=3 > GDAL_netCDF: setting file type to 3, was 5 > GDAL_netCDF: dim_count = 2 > GDAL_netCDF: var_count = 4 > GDAL_netCDF: NCDFGetAttr unsupported type 7 for attribute _FillValue > GDAL_netCDF: NCDFGetAttr unsupported type 7 for attribute missing_value > GDAL_netCDF: NCDFGetAttr unsupported type 7 for attribute flag_values > GDAL_netCDF: NCDFGetAttr unsupported type 7 for attribute valid_range > GDAL_netCDF: > ===== > SetProjectionFromVar( 3) > *GDAL_netCDF: got grid_mapping crs* > GDAL_netCDF: bIsGdalFile=1 bIsGdalCfFile=0 bBottomUp=0 > GDAL_netCDF: got spheroid from CF: (6378137.000000 , 298.257224) > GDAL_netCDF: set bBottomUp = 0 from Y axis > GDAL_netCDF: setting WKT from CF > GDAL_netCDF: SetProjection, WKT = > GEOGCS["unknown",DATUM["unknown",SPHEROID["Spheroid",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]]] > > GDAL_netCDF: xdim: 120960 nSpacingBegin: 3 nSpacingMiddle: 3 > nSpacingLast: 3 > GDAL_netCDF: ydim: 47040 nSpacingBegin: -3 nSpacingMiddle: -3 > nSpacingLast: -3 > GDAL_netCDF: setting WKT from GDAL > GDAL_netCDF: SetProjection, WKT = GEOGCS["WGS > 84",DATUM["WGS_1984",SPHEROID["WGS > 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9108"]],AUTHORITY["EPSG","4326"]] > > *GDAL_netCDF: > SetGeoTransform(-180.001488,0.002976,0.000000,80.001488,0.000000,-0.002976) > * > GDAL_netCDF: bGotGeogCS=1 bGotCfSRS=1 bGotCfGT=1 bGotGdalSRS=1 bGotGdalGT=0 > Warning 1: Unsupported netCDF datatype (7), treat as Float32. > GDAL_netCDF: NCDFGetAttr unsupported type 7 for attribute _FillValue > GDAL_netCDF: netcdf type=5 gdal type=6 signedByte=1 > GDAL_netCDF: NCDFGetAttr unsupported type 7 for attribute _FillValue > GDAL_netCDF: NCDFGetAttr unsupported type 7 for attribute missing_value > GDAL_netCDF: NCDFGetAttr unsupported type 7 for attribute flag_values > GDAL_netCDF: NCDFGetAttr unsupported type 7 for attribute valid_range > GDAL_netCDF: got add_offset=-0.07999999821186066, status=0 > GDAL_netCDF: got scale_factor=0.004000000189989805, status=0 > GDAL: GDALOpen(netcdf:c_gls_NDVI300_201910110000_GLOBE_PROBAV_V1.0.1.nc, > this=00000219E2D291F0) succeeds as netCDF. > Driver: netCDF/Network Common Data Format > GDAL: GDALDefaultOverviews::OverviewScan() > Files: none associated > Size is 120960, 47040 > Coordinate System is: > GEOGCS["WGS 84", > DATUM["WGS_1984", > SPHEROID["WGS 84",6378137,298.257223563, > AUTHORITY["EPSG","7030"]], > TOWGS84[0,0,0,0,0,0,0], > AUTHORITY["EPSG","6326"]], > PRIMEM["Greenwich",0, > AUTHORITY["EPSG","8901"]], > UNIT["degree",0.0174532925199433, > AUTHORITY["EPSG","9108"]], > AUTHORITY["EPSG","4326"]] > *Origin = (-180.001488095238102,80.001488095238088)* > Pixel Size = (0.002976190476204,-0.002976190476190) > Metadata: > * crs#GeoTransform=-180.0000000000 0.0029761905 0.0 80.0000000000 0.0 > -0.0029761905* > crs#grid_mapping_name=latitude_longitude > crs#inverse_flattening=298.257223563 > crs#longitude_of_prime_meridian=0 > crs#long_name=coordinate reference system > crs#semi_major_axis=6378137 > crs#spatial_ref=GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS > 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9108"]],AUTHORITY["EPSG","4326"]] > > crs#_CoordinateAxisTypes=GeoX GeoY > crs#_CoordinateTransformType=Projection > lat#axis=Y > lat#DIMENSION_LABELS=lat > lat#long_name=latitude > lat#standard_name=latitude > lat#units=degrees_north > lat#_CoordinateAxisType=Lat > lon#axis=X > lon#DIMENSION_LABELS=lon > lon#long_name=longitude > lon#standard_name=longitude > lon#units=degrees_east > lon#_CoordinateAxisType=Lon > NC_GLOBAL#archive_facility=VITO > NC_GLOBAL#Conventions=CF-1.6 > NC_GLOBAL#copyright=Copernicus Service information 2019 > NC_GLOBAL#history=Processing line NDVI: 2019-10-22 > > NC_GLOBAL#identifier=urn:cgls:global:ndvi300_v1_333m:NDVI300_201910110000_GLOBE_PROBAV_V1.0.1 > > NC_GLOBAL#institution=VITO NV > NC_GLOBAL#long_name=Normalized Difference Vegetation Index > NC_GLOBAL#orbit_type=LEO > NC_GLOBAL#parent_identifier=urn:cgls:global:ndvi300_v1_333m > NC_GLOBAL#platform=Proba-V > NC_GLOBAL#processing_level=L3 > NC_GLOBAL#processing_mode=Near Real Time > NC_GLOBAL#product_version=V1.0.1 > NC_GLOBAL#references=http://land.copernicus.eu/global/products/ndvi > NC_GLOBAL#sensor=VEGETATION > NC_GLOBAL#source=Derived from EO satellite imagery > NC_GLOBAL#time_coverage_end=2019-10-20T23:59:59Z > NC_GLOBAL#time_coverage_start=2019-10-11T00:00:00Z > NC_GLOBAL#title=10-daily Normalized Difference Vegetation Index 333M: > GLOBE 2019-10-11T00:00:00Z > NDVI#add_offset=-0.079999998 > NDVI#flag_meanings=Missing cloud snow sea background > NDVI#flag_values={} > NDVI#grid_mapping=crs > NDVI#long_name=Normalized Difference Vegetation Index 333M > NDVI#missing_value= > NDVI#scale_factor=0.0040000002 > NDVI#standard_name=normalized_difference_vegetation_index > NDVI#units= > NDVI#valid_range={} > NDVI#_FillValue= > OGRCT: PROJ >= 4.8.0 features enabled > OGRCT: Using locale-safe proj version > OGRCT: Source: +proj=longlat +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +no_defs > OGRCT: Target: +proj=longlat +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +no_defs > Corner Coordinates: > *Upper Left (-180.0014881, 80.0014881) (180d 0' 5.36"W, 80d 0' 5.36"N)* > *Lower Left (-180.0014881, -59.9985119) (180d 0' 5.36"W, 59d59'54.64"S)* > *Upper Right ( 179.9985119, 80.0014881) (179d59'54.64"E, 80d 0' 5.36"N)* > *Lower Right ( 179.9985119, -59.9985119) (179d59'54.64"E, 59d59'54.64"S)* > Center ( -0.0014881, 10.0014881) ( 0d 0' 5.36"W, 10d 0' 5.36"N) > Band 1 Block=120960x1 Type=Float32, ColorInterp=Undefined > NoData Value=0 > Offset: -0.0799999982118607, Scale:0.00400000018998981 > Metadata: > add_offset=-0.079999998 > flag_meanings=Missing cloud snow sea background > flag_values={} > grid_mapping=crs > long_name=Normalized Difference Vegetation Index 333M > missing_value= > NETCDF_VARNAME=NDVI > scale_factor=0.0040000002 > standard_name=normalized_difference_vegetation_index > units= > valid_range={} > _FillValue= > GDAL: > GDALClose(netcdf:c_gls_NDVI300_201910110000_GLOBE_PROBAV_V1.0.1.nc, > this=00000219E2D291F0) > > > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > https://lists.osgeo.org/mailman/listinfo/gdal-dev > _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org 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