[gdal-dev] NetCDF and ESA Probav issue with corner coordimates

Fri Nov 1 04:24:27 PDT 2019

Does
   https://gis.stackexchange.com/questions/122670/is-there-a-standard-for-the-coordinates-of-pixels-in-georeferenced-rasters#122687
help you to understand the issue ?

On Fri, 1 Nov 2019, Richard Duivenvoorde wrote:

> 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)
>>
>>
>>
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>>
>
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