Hi Stefan, Thanks for the hint. I often use '-o'. In this case after discussion with the data provider it turns out that it was not EPSG:3413 but instead some custom projection, even though part of the NetCDF file reported EPSG:3413 in the metadata.
Unfortunately r.import does not work. I get the errors below. Given the 0..3..6..9... it appears to import something, but no raster exists when the command finishes. r.import input=NetCDF:file.nc:surface output=surface WARNING: Datum <unnamed> not recognised by GRASS and no parameters found WARNING: Projection of dataset does not appear to match current location. Location PROJ_INFO is: name: WGS 84 / NSIDC Sea Ice Polar Stereographic North datum: wgs84 ellps: wgs84 proj: stere lat_0: 90 lat_ts: 70 lon_0: -45 x_0: 0 y_0: 0 no_defs: defined init: EPSG:3413 Dataset PROJ_INFO is: name: unnamed a: 6378273 es: 0.006693883000000017 proj: stere lat_0: 90 lat_ts: 70 lon_0: -45 x_0: 0 y_0: 0 no_defs: defined ERROR: datum WARNING: Datum <unnamed> not recognised by GRASS and no parameters found WARNING: Datum <unnamed> not recognised by GRASS and no parameters found Importing raster map <surface>... 0..3..6..9..12..15..18..21..24..27..30..33..36..39..42..45..48..51..54..57..60..63..66..69..72..75..78..81..84..87..90..93..96..99..100 ERROR: Unable to open element file <windows> for <tmp.r.import.3257873@PERMANENT> ERROR: Unable to get reprojected map extent -k. On Sat, Jul 24, 2021 at 2:19 PM Stefan Blumentrath < [email protected]> wrote: > Hei Ken, > > Did you try the -o flag ("Override projection check (use current > location's projection) > Assume that the dataset has same projection as the current location")? > https://grass.osgeo.org/grass78/manuals/r.external.html > As the error message suggests? > > If you are sure that projections in fact match, a mismatch in CRS > description can be overridden that way, without modifying the input file. > > Alternatively, you can use r.import to reproject while converting to GRASS > format or you create a new location... > > Cheers > Stefan > > > -----Original Message----- > From: grass-user <[email protected]> On Behalf Of Ken > Mankoff > Sent: fredag 23. juli 2021 19:33 > To: GRASS user list <[email protected]> > Subject: [GRASS-user] Cannot read NetCDF with 'semi_major_axis' or > 'inverse_flattening' > > Hello list, > > I have been given an updated NetCDF file - everything is the same as the > old version except there are two new attributes in the 'mapping' variable: > > char mapping ; > mapping:geoid = "eigen-6c4" ; > mapping:grid_mapping_name = "polar_stereographic" ; > mapping:latitude_of_projection_origin = 90. ; > mapping:standard_parallel = 70. ; > mapping:straight_vertical_longitude_from_pole = -45. ; > mapping:semi_major_axis = 6378273. ; > mapping:inverse_flattening = 298.27940504282 ; > mapping:false_easting = 0. ; > mapping:false_northing = 0. ; > mapping:_Storage = "contiguous" ; > > > Specifically: > mapping:semi_major_axis = 6378273. ; > mapping:inverse_flattening = 298.27940504282 ; > > When I try to load this file with: > > r.external source=netCDF:file.nc:surface output=surface > > I get this error: > > WARNING: Datum <unnamed> not recognised by GRASS and no parameters found > ERROR: Projection of dataset does not appear to match current location. > > Location PROJ_INFO is: > name: WGS 84 / NSIDC Sea Ice Polar Stereographic North > datum: wgs84 > ellps: wgs84 > proj: stere > lat_0: 90 > lat_ts: 70 > lon_0: -45 > x_0: 0 > y_0: 0 > no_defs: defined > init: EPSG:3413 > > Dataset PROJ_INFO is: > name: unnamed > a: 6378273 > es: 0.006693883000000017 > proj: stere > lat_0: 90 > lat_ts: 70 > lon_0: -45 > x_0: 0 > y_0: 0 > no_defs: defined > > ERROR: datum > > In case of no significant differences in the projection definitions, use > the -o flag to ignore them and use current location definition. > Consider generating a new location from the input dataset using the > 'location' parameter. > > > If I remove thos two attributes (semi_major_axis and inverse_flattening) > with: > > ncatted -O -h -a semi_major_axis,mapping,d,l,6378273 -a > inverse_flattening,mapping,d,f,298.27940504282 file.nc foo.nc > > And then try to read in the data, it works. > > Is there some reason that those two attributes make it difficult to load > the data in GRASS? Is there a better work-around than removing them? The > documented projection of the data has not changed, only some of the > metadata. > > Versions: > gdal 3.0.4 > grass 7.8.2 > > Thank you, > > -k. > > _______________________________________________ > grass-user mailing list > [email protected] > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.osgeo.org%2Fmailman%2Flistinfo%2Fgrass-user&data=04%7C01%7C%7C900b853648c545edd6fd08d94dffe4cb%7C6cef373021314901831055b3abf02c73%7C0%7C0%7C637626583719044920%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=wWKyBuAKwbuobSGVQ6q97VXj1OIiCLSN9NlbXDLw7tc%3D&reserved=0 >
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