[Proj] crs definition with both +nadgrids and +towgs84 parameters

"SAEZ Laurent - CETE Méditerr./DI/ETER" Laurent.Saez at developpement-durable.gouv.fr
Wed Jan 14 02:22:51 EST 2009

Hi List,

Someone could tell me what appens if +nadgrids and +towgs84 are both 
used in a crs definition (e.g. in the EPSG file) ?
Which parameter is taken into account ?
Is the behavior the same in all tools (cs2cs, ogr utilities, gdal 
utilities, mapserver,PostGIS...)
I ask this because IGN puts both parameters in its IGNF catalog (French 
I wonder if it is not preferable to specify only one.
My main problem is to be sure that the grid ntf_r93.gsb is used by
MapServer for NTF to RGF93 transformations.



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