[gdal-dev] GetProjectionRef returns invalid projection

[Even Rouault]

Tihs works fine for me:

$ python -c "from osgeo import gdal; ds= 
gdal.Open('/home/even/Téléchargements/OFM.tif'); 
print(ds.GetProjectionRef())"
PROJCS["WGS 84 / Pseudo-Mercator",GEOGCS["WGS 
84",DATUM["WGS_1984",SPHEROID["WGS 
84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4326"]],PROJECTION["Mercator_1SP"],PARAMETER["central_meridian",0],PARAMETER["scale_factor",1],PARAMETER["false_easting",0],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],EXTENSION["PROJ4","+proj=merc 
+a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m 
+nadgrids=@null +wktext +no_defs"],AUTHORITY["EPSG","3857"]]

However I suspect that your issue is that PROJ is misconfigured and 
cannot find its proj.db. Make sure that PROJ_LIB points to the directory 
where proj.db is located

I can reproduce your issue by setting a wrong path for PROJ_LIB:

$ PROJ_LIB=/unexisting/path python -c "from osgeo import gdal; ds= 
gdal.Open('/home/even/Téléchargements/OFM.tif'); 
print(ds.GetProjectionRef())"
Warning 1: PROJ: proj_create_from_database: Cannot find proj.db
Warning 1: The definition of projected CRS EPSG:3857 got from GeoTIFF 
keys is not the same as the one from the EPSG registry, which may cause 
issues during reprojection operations. Set GTIFF_SRS_SOURCE 
configuration option to EPSG to use official parameters (overriding the 
ones from GeoTIFF keys), or to GEOKEYS to use custom values from GeoTIFF 
keys and drop the EPSG code.
LOCAL_CS["WGS 84 / 
Pseudo-Mercator",UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH]]

Le 15/04/2022 à 13:52, Frank Hübenthal a écrit :
> Here it is: https://easyupload.io/rg2ltd
>
> Unfortunately It is rather big (36MB).
>
> Best regards,
>
> Frank
>
> Am 15.04.2022 um 13:41 schrieb Even Rouault:
>> Frank,
>>
>> please provide a link to such file
>>
>> Even
>>
>> Le 15/04/2022 à 13:27, Frank Hübenthal a écrit :
>>> I use GDAL C++ to load GeoTIFF files. Since I moved to GDAL 3.4 I 
>>> have problems to get the projection string from some (not all) of 
>>> these GeoTIFF files. With GDAL 3.2 still something like this was 
>>> returned:
>>>
>>> PROJCS["WGS 84 / Pseudo-Mercator",GEOGCS["WGS 
>>> 84",DATUM["WGS_1984",SPHEROID["WGS 
>>> 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4326"]],PROJECTION["Mercator_1SP"],PARAMETER["central_meridian",0],PARAMETER["scale_factor",1],PARAMETER["false_easting",0],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],EXTENSION["PROJ4","+proj=merc 
>>> +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m 
>>> +nadgrids=@null +wktext +no_defs"],AUTHORITY["EPSG","3857"]]
>>>
>>> With GDAL 3.4 I get for the same map file only this:
>>>
>>> "LOCAL_CS["WGS 84 / 
>>> Pseudo-Mercator",UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","3857"]]"
>>>
>>> I use the projection to create finally a transformation, but 
>>> OGRCreateCoordinateTransformation returns NULL with the short string 
>>> from GDAL 3.4 while it was still working with 3.2.
>>>
>>> Best regards,
>>>
>>> Frank
>>>
>>>
>>> _______________________________________________
>>> gdal-dev mailing list
>>> gdal-dev at lists.osgeo.org
>>> https://lists.osgeo.org/mailman/listinfo/gdal-dev
>>
>
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