[GRASS-user] Problem importing netCDF

GRASS GRASS user
,
1

Hi,

I'm using Win XP and GRASS 6.4RC6 to import a TRMM netCDF file using
the command:
-----
r.in.gdal -o input =c:/data/3B42.000202.0.6.nc output=test band=precipitation
-----

and am getting the error:
-----
G_set_window(): Illegal latitude for North
-----

gdalinfo for the file outputs:
-----
Driver: netCDF/Network Common Data Format
Files: C:\data\3B42.000202.0.6.nc
       C:\data\3B42.000202.0.6.nc.aux.xml
Size is 512, 512
Coordinate System is `'
Metadata:
  NC_GLOBAL#Conventions=CF-1.0
Subdatasets:
  SUBDATASET_1_NAME=NETCDF:"C:\data\3B42.000202.0.6.nc":precipitation
  SUBDATASET_1_DESC=[400x1440] precipitation (32-bit floating-point)
  SUBDATASET_2_NAME=NETCDF:"C:\data\3B42.000202.0.6.nc":relativeError
  SUBDATASET_2_DESC=[400x1440] relativeError (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)
-----

In Panoply (http://www.giss.nasa.gov/tools/panoply/), the information
for the file displays as:
-----
netcdf file:/C:/data/3B42.000202.0.6.nc {
dimensions:
   lat = 400;
   lon = 1440;
variables:
   float precipitation(lat=400, lon=1440);
     :long_name = "precipitation";
     :units = "mm hr-1";
     :_FillValue = -9999.9f; // float
   float relativeError(lat=400, lon=1440);
     :long_name = "relativeError";
     :units = "mm hr-1";
     :_FillValue = -9999.9f; // float
   float lat(lat=400);
     :standard_name = "latitude";
     :units = "degrees_north";
     :long_name = "latitude";
     :_CoordinateAxisType = "Lat";
   float lon(lon=1440);
     :standard_name = "longitude";
     :units = "degrees_east";
     :long_name = "longitude";
     :_CoordinateAxisType = "Lon";

:Conventions = "CF-1.0";
}
-----

In the Panoply array display, the coordinates range from 49.875° to
-49.875° (lattitude) and -179.875° to +179.875° longitude. These are
coordinates for the centres of 0.25° grid cells.

I have set my region according to the documentation for the dataset to:
-----
projection: 3 (Latitude-Longitude)
zone: 0
datum: wgs84
ellipsoid: wgs84
north: 50N
south: 50S
west: 180W
east: 180E
nsres: 0:15
ewres: 0:15
rows: 400
cols: 1440
cells: 576000
-----

Can someone perhaps spot my error?

Thanks
Hanlie

2

Hanlie wrote:

I'm using Win XP and GRASS 6.4RC6 to import a TRMM netCDF
file using the command:
-----
r.in.gdal -o input =c:/data/3B42.000202.0.6.nc output=test
band=precipitation
-----

and am getting the error:
-----
G_set_window(): Illegal latitude for North
-----

gdalinfo for the file outputs:
-----
Driver: netCDF/Network Common Data Format
Files: C:\data\3B42.000202.0.6.nc
   
   C:\data\3B42.000202.0.6.nc.aux.xml
Size is 512, 512
Coordinate System is `'
Metadata:
  NC_GLOBAL#Conventions=CF-1.0
Subdatasets:

SUBDATASET_1_NAME=NETCDF:"C:\data\3B42.000202.0.6.nc":precipitation
  SUBDATASET_1_DESC=[400x1440] precipitation (32-bit
floating-point)

SUBDATASET_2_NAME=NETCDF:"C:\data\3B42.000202.0.6.nc":relativeError
  SUBDATASET_2_DESC=[400x1440] relativeError (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)
-----

in a lat-lon location you can no exceed 90 degrees North or 90 degrees
South.

Your data file has a coordinate system unknown to GDAL (empty) so it
tries to import it with 1 pixel = 1 degree, and gets upset with a coord
of 512 degrees north.

Newer versions of GRASS (6.5+?) have a flag in r.in.gdal to force the map
to fit into geographic space, then you can use r.region to fix the bounds
manually. If you look on the GRASS wiki's "MODIS" page I think you can
find some examples of how to fix this with gdal_translate. The general
idea is to use gdal_translate to extract a GeoTiff from the netCDF file
and set the coord system and geographic bounds, then import that GeoTiff
into GRASS.

In Panoply (http://www.giss.nasa.gov/tools/panoply/), the
information
for the file displays as:
-----
netcdf file:/C:/data/3B42.000202.0.6.nc {
dimensions:
   lat = 400;
   lon = 1440;
variables:
   float precipitation(lat=400, lon=1440);
     :long_name = "precipitation";
     :units = "mm hr-1";
     :_FillValue = -9999.9f; // float
   float relativeError(lat=400, lon=1440);
     :long_name = "relativeError";
     :units = "mm hr-1";
     :_FillValue = -9999.9f; // float
   float lat(lat=400);
     :standard_name = "latitude";
     :units = "degrees_north";
     :long_name = "latitude";
     :_CoordinateAxisType = "Lat";
   float lon(lon=1440);
     :standard_name = "longitude";
     :units = "degrees_east";
     :long_name = "longitude";
     :_CoordinateAxisType = "Lon";

:Conventions = "CF-1.0";
}
-----

In the Panoply array display, the coordinates range from
49.875° to
-49.875° (lattitude) and -179.875° to +179.875°
longitude. These are
coordinates for the centres of 0.25° grid cells.

I have set my region according to the documentation for the
dataset to:
-----
projection: 3 (Latitude-Longitude)
zone: 0
datum: wgs84
ellipsoid: wgs84
north: 50N
south: 50S
west: 180W
east: 180E
nsres: 0:15
ewres: 0:15
rows: 400
cols: 1440
cells: 576000
-----

good luck,
Hamish