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I have a grid file in a certain coordinate system. I'd like to change it so I have the same grid in geographic lat/long based on WGS84. This seems like something that gdal can tackle quite easily (maybe with gdalwarp or gdal_translate) but for some reason I can't find the proper way to do it.

I'm trying to run the following:

gdalwarp -s_srs '+proj=cass +lat_0=31.73409694444445 +lon_0=35.21208055555556 
+x_0=170251.555 +y_0=1126867.909 +a=6378300.789 +b=6356566.435
+towgs84=-275.722,94.7824,340.894,-8.001,-4.42,-11.821,1 +units=m +no_defs'
-t_srs EPSG:4326 thick.grd thick2.grd

The proj4 definition taken from spatialreference.org. I get the following error message:

Warning: The target file has a 'grd' extension, which is normally used by the GSAG, GSBG, GS7BG, NWT_GRD drivers,
but the requested output driver is GTiff. Is it really what you want ?
ERROR 6: Unable to load PROJ.4 library (libproj.so), creation of
OGRCoordinateTransformation failed.

So I have two problems here. First, how do I let gdalwarp know what is the input format (in this case, Surfer grid) and the output format? Also, why can't it load the PROJ.4 library if I have it installed? Is there an alternative to PROJ.4 that will work on my system?

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2 Answers 2

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For the first part of your question:

GDAL can guess the format of the input file from the file extension. The output format is defined by the -f option. If it is missing, Geotiff is assumed, but you get that warning if the file extension is not .tif.

For a .grd output, you can select between

GS7BG (rw+v): Golden Software 7 Binary Grid (.grd)
GSAG (rwv): Golden Software ASCII Grid (.grd)
GSBG (rw+v): Golden Software Binary Grid (.grd)

The second part might depend on your operating system, and where you got the binaries from.

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  • I'm on openSUSE. Binaries from the openSUSE repo.
    – Gimelist
    Commented Nov 16, 2014 at 16:09
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    I have not much experience with openSUSE. I added your suggested edit to your own answer.
    – AndreJ
    Commented Nov 16, 2014 at 17:21
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In addition to AndreJ's answer, the gdalwarp command can be simplified as this:

gdalwarp -s_srs EPSG:28193 -t_srs EPSG:4326 -of GS7BG in.grd out.grd

No need to specify the entire proj.4 definition.

On Linux systems this might work, as root:

ln -s /usr/lib64/libproj.so.0 /usr/lib64/libproj.so
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