[gdal-dev] Proj4 Transformation Error 6

[Kyle Shannon]

Jay,


On Fri, Jun 12, 2015 at 11:21 AM, Kyle Shannon <kyle at pobox.com> wrote:
> Jay,
>
>
> On Fri, Jun 12, 2015 at 10:59 AM, Jay L. <jlaura at asu.edu> wrote:
>> Using GDAL 1.11.2 (Anaconda Python osgeo binstar install).
>>
>> I have a WKT projection:
>> 'PROJCS["Mercator",GEOGCS["GCS_Moon_2000",DATUM["D_Moon_2000",SPHEROID["Moon_2000_IAU_IAG",1737400.0,0.0]],PRIMEM["Reference_Meridian",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Mercator"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",180.0],PARAMETER["Standard_Parallel_1",0.0],UNIT["Meter",1.0]]'
>>
>> I import this into a srs object and attempt to export to Proj4.  This is
>> throwing:
>>
>> RuntimeError: No translation for Mercator to PROJ.4 format is known.
>
> OGRSpatialReference needs a specific Mercator projection such as:
> Mercator_1SP, Mercator_2SP, etc.  Use Mercator_1SP in your case for
> the PROJECTION parameter.
>
>>
>> Along the same lines, I am trying to compute pixel to latlon and the
>> inverse.  So I need a transformation object.  No problem setting that up
>> until:
>>
>> RuntimeError: Failed to initialize PROJ.4 with `+proj=merc +lon_0=0 +k=0
>> +x_0=0 +y_0=0 +a=3396190 +b=3376200 +units=m +no_defs '.
>>
>> Which leads me to try:
>>
>> gdalsrsinfo -V '+proj=merc +lon_0=0 +k=0 +x_0=0 +y_0=0 +a=3396190 +b=3376200
>> +units=m +no_defs'
>>
>> Validate Succeeds
>>
>> PROJ.4 : '+proj=merc +lon_0=0 +k=0 +x_0=0 +y_0=0 +a=3396190 +b=3376200
>> +units=m +no_defs '
>>
>> OGC WKT :
>> PROJCS["unnamed",
>>     GEOGCS["unnamed ellipse",
>>         DATUM["unknown",
>>             SPHEROID["unnamed",3396190,169.894447223611]],
>>         PRIMEM["Greenwich",0],
>>         UNIT["degree",0.0174532925199433]],
>>     PROJECTION["Mercator_1SP"],
>>     PARAMETER["central_meridian",0],
>>     PARAMETER["scale_factor",0],
>>     PARAMETER["false_easting",0],
>>     PARAMETER["false_northing",0],
>>     UNIT["Meter",1]]
>>
>> So gdalsrsinfo is able to validate the proj4 string.
>
> gdalsrsinfo can't validate the WKT though, without the Mercator_1SP
>
>>
>> Any ideas?
>>
>>
>> _______________________________________________
>> gdal-dev mailing list
>> gdal-dev at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>
>
>
> --
> Kyle

Mercator is a valid key in the ESRI WKT dialect:

Type "copyright", "credits" or "license()" for more information.
>>> from osgeo import osr
>>> wkt = 'PROJCS["Mercator",GEOGCS["GCS_Moon_2000",DATUM["D_Moon_2000",SPHEROID["Moon_2000_IAU_IAG",1737400.0,0.0]],PRIMEM["Reference_Meridian",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Mercator"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",180.0],PARAMETER["Standard_Parallel_1",0.0],UNIT["Meter",1.0]]'
>>> srs1 = osr.SpatialReference()
>>> srs1.ImportFromWkt(wkt)
0
>>> srs1.ExportToProj4()
''
>>> srs1.MorphFromESRI()
0
>>> srs1.ExportToProj4()
'+proj=merc +lon_0=180 +k=1 +x_0=0 +y_0=0 +a=1737400 +b=1737400
+units=m +no_defs '

The osr.SpatialReference.MorphFromESRI() should do the job too.

-- 
Kyle