[gdal-dev] projection of (maybe broken) grib file

[teeschke]

Hi list

We have a grib file, that gets cropped after a projection from WGS84 to
WebMercator. The issue occurs in UMN Mapserver and QGIS. ArcMap can project
the grib file correctly - so I think its a GDAL thing.

<http://osgeo-org.1560.x6.nabble.com/file/n5164353/grib_projection_cutting.jpg> 

Extracting the metadata with gdalinfo points out that the original corner
coordinates are shifted a little bit.

$ gdalinfo 2014-09-28T00\:00Z.grb
Driver: GRIB/GRIdded Binary (.grb)
Files: 2014-09-28T00:00Z.grb
Size is 1440, 721
Coordinate System is:
GEOGCS["Coordinate System imported from GRIB file",
    DATUM["unknown",
        SPHEROID["Sphere",6367470,0]],
    PRIMEM["Greenwich",0],
    UNIT["degree",0.0174532925199433]]
Origin = (-179.875000000000000,90.125000000000000)
Pixel Size = (0.250000000000000,-0.250000000000000)
Corner Coordinates:
Upper Left  (-179.8750000,  90.1250000) (179d52'30.00"W, 90d 7'30.00"N)
Lower Left  (-179.8750000, -90.1250000) (179d52'30.00"W, 90d 7'30.00"S)
Upper Right ( 180.1250000,  90.1250000) (180d 7'30.00"E, 90d 7'30.00"N)
Lower Right ( 180.1250000, -90.1250000) (180d 7'30.00"E, 90d 7'30.00"S)
Center      (   0.1250000,   0.0000000) (  0d 7'30.00"E,  0d 0' 0.01"N)
Band 1 Block=1440x1 Type=Float64, ColorInterp=Undefined
  Description = 0[-] SFC (Ground or water surface)
  Metadata:
    GRIB_COMMENT=Total precipitation [m]
    GRIB_ELEMENT=TP
    GRIB_FORECAST_SECONDS=172800 sec
    GRIB_REF_TIME=  1411689600 sec UTC
    GRIB_SHORT_NAME=0-SFC
    GRIB_UNIT=[m]
    GRIB_VALID_TIME=  1411862400 sec UTC

A converted GTiff from has the same behavior.
$ gdal_translate ./2014-09-28T00\:00Z.grb -of GTiff -a_srs EPSG:4326
translated_tiff.tif

Thanks and best regards
teeschke



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