[GRASS-user] GRIB2 r.in.gdal problem

[Lee Eddington]

I upgraded gdal to 1.10 and used r.in.gdal -l and was able to read the file and display it with no problems.

Thanks,
Lee


On Feb 13, 2014, at 5:35 PM, Hamish <hamish_b at yahoo.com> wrote:

> (sorry for top posting, no time to deal with yahoo mail today)
> 
> Hi,
> 
> note for GRIB you need gdal 1.10 or newer, there were
> edge coordinate bugs in earlier versions.
> 
> 
> ---> see:  http://grasswiki.osgeo.org/wiki/GRIB
> 
> 
> note grass uses the cell-center for data value convention,
> not the data values at grid line confluences (nodes) convention for raster arrays.
> 
> 
> and so in grass the region's e,w,s,n values are at the outer edge of the raster cells, while gridline-centered arrays* would give coords overhanging the edges of the region by half a cell.
> 
> sometimes when loading in gridline-centered data you need to crop away the data row at 90N,S and one of the two at 0,360 or +-180 longitude. See the MODIS page in the wiki perhaps.
> the way there is to use 'r.in.gdal -l' to force it to fit into 90N,S, then carefully use g.region + r.mapcalc to crop away the two rows, then use r.region to fix the map bounds back to where they should.
> 
> resolution ends up with bounds at e.g. 25,75m with a cell size of 50m, you have to be careful that d.zoom or 'g.region -a' doesn't realign the bounds to 0,50,100m instead of 25,75 (so silently shifted by 1/2 a cell). 
> 
> 
> 
> * (usually can spot them as they have like 501x1001 cells not 500x1000)
> 
> 
> 
> http://grasswiki.osgeo.org/wiki/GRASS_raster_semantics#Cell_Locations
> 
> http://grasswiki.osgeo.org/wiki/GRASS_FAQ#Errors
> 
> 
> but the first thing to verify for the GRIB format is that your gdal version is 1.10 or newer.
> 
> 
> regards,
> 
> Hamish
> 
> 
> On Wednesday, February 12, 2014 6:21 PM, Lee Eddington <lee.w.eddington at gmail.com> wrote:
> 
> I’m trying to import some GRIB2 data into GRASS (6.4.3 on a Mac) and am having a problem with the range of the latitude coordinates.  I’m working with the following file:
>> 
>>     http://www.ftp.ncep.noaa.gov/data/nccf/com/gfs/prod/gfs.2014021112/gfs.t12z.master.grbf72.10m.uv.grib2
>> 
>> I used gdal_translate to create a GeoTiff file, but when I try to import it into a lat/lon location I get the following:
>> 
>> GRASS 6.4.3 (GFS_from_grib):~ > r.in.gdal input=gfs.t12z.master.grbf72.10m.uv.tif output=gfs
>> WARNING: Datum <unknown> not recognised by GRASS and no parameters found
>> Projection of input dataset and current location appear to match
>> WARNING: G_set_window(): Illegal latitude for North
>> 
>> Here is the output from gdalinfo:
>> 
>> lees-mbp:GFS Lee$ gdalinfo gfs.t12z.master.grbf72.10m.uv.tif
>> Driver: GTiff/GeoTIFF
>> Files: gfs.t12z.master.grbf72.10m.uv.tif
>>        gfs.t12z.master.grbf72.10m.uv.tif.aux.xml
>> Size is 720, 361
>> Coordinate System
> is:
>> GEOGCS["Coordinate System imported from GRIB file",
>>     DATUM["unknown",
>>         SPHEROID["Sphere",6371229,0]],
>>     PRIMEM["Greenwich",0],
>>     UNIT["degree",0.0174532925199433]]
>> Origin = (-0.250000000000000,90.250000000000000)
>> Pixel Size = (0.500000000000000,-0.500000000000000)
>> Metadata:
>>   AREA_OR_POINT=Area
>> Image Structure Metadata:
>>   INTERLEAVE=PIXEL
>> Corner Coordinates:
>> Upper Left  (  -0.2500000,  90.2500000) (  0d15' 0.00"W, 90d15' 0.00"N)
>> Lower Left  (  -0.2500000, -90.2500000) (  0d15' 0.00"W, 90d15' 0.00"S)
>> Upper Right (     359.750,      90.250) (359d45' 0.00"E, 90d15' 0.00"N)
>> Lower Right (     359.750,     -90.250) (359d45' 0.00"E, 90d15' 0.00"S)
>> Center      ( 179.7500000,   0.0000000) (179d45' 0.00"E,  0d 0' 0.01"N)
>> Band 1
> Block=720x1 Type=Float64, ColorInterp=Gray
>>   Description = 10[m] HTGL="Specified height level above ground"
>>   Metadata:
>>     GRIB_COMMENT=u-component of wind [m/s]
>>     GRIB_ELEMENT=UGRD
>>     GRIB_FORECAST_SECONDS=259200 sec
>>     GRIB_PDS_PDTN=0
>>     GRIB_PDS_TEMPLATE_NUMBERS=2 2 2 0 96 0 0 0 1 0 0 0 72 103 0 0 0 0 10 255 0 0 0 0 0
>>     GRIB_REF_TIME=1392120000 sec UTC
>>     GRIB_SHORT_NAME=10-HTGL
>>     GRIB_UNIT=[m/s]
>>     GRIB_VALID_TIME=1392379200 sec UTC
>> Band 2 Block=720x1 Type=Float64, ColorInterp=Undefined
>>   Description = 10[m] HTGL="Specified height level above ground"
>>   Metadata:
>>     GRIB_COMMENT=v-component of wind [m/s]
>>     GRIB_ELEMENT=VGRD
>>     GRIB_FORECAST_SECONDS=259200 sec
>>     GRIB_REF_TIME=1392120000 sec UTC
>>    
> GRIB_SHORT_NAME=10-HTGL
>>     GRIB_UNIT=[m/s]
>>     GRIB_VALID_TIME=1392379200 sec UTC
>> 
>> So it’s showing the north and south bounds of 90.25 N and -90.25 S.  I’m almost positive that this would be the values of the edges of the cells and that the cells are centered at 90 N and 90 S.
>> 
>> Is there a way to import this data?
>> 
>> Thanks,
>> Lee
>> 
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>> 
>>