[gdal-dev] Proj4 Transformation Error 6

Kyle Shannon kyle at pobox.com
Fri Jun 12 10:21:46 PDT 2015


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?
>
>
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-- 
Kyle


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