[Gdal-dev] Does GDAL handle rotated spheres?

[Frank Warmerdam]

Kolberg Sjur A wrote:
> Hello list,
> 
> Does GDAL handle rotated spheres?
> 
> According to this mail from 2005, GDAL re-implements a subset of Proj4's
> keycodes, unfortuately excluding ob_tran.
> 
> http://lists.maptools.org/pipermail/gdal-dev/2005-June/005839.html
> <http://lists.maptools.org/pipermail/gdal-dev/2005-June/005839.html>
> 
> Is this correctly described and still valid? Is there any known workaround
> or plans for extension?

Sjur,

A mechanism to embed PROJ.4 strings with more parameters than are actually
known to OGR has been implemented.  I think if you used importFromWkt()
instead on the following you would get the transformation you wish.

PROJCS["Plate_Carree",
     GEOGCS["unnamed ellipse",
         DATUM["D_unknown",
             SPHEROID["Unknown",6371000,0]],
         PRIMEM["Greenwich",0],
         UNIT["Degree",0.017453292519943295]],
     PROJECTION["Plate_Carree"],
     PARAMETER["latitude_of_origin",0],
     PARAMETER["central_meridian",-40],
     PARAMETER["false_easting",639367],
     PARAMETER["false_northing",1473324],
     EXTENSION["PROJ4","+proj=ob_tran +o_proj=eqc +lon_0=-40 +o_lat_p=22 
+x_0=639367 +y_0=1473324 +a=6371000 +b=6371000 +wktext"],
     UNIT["Meter",1]]

Note the EXTENSION[] item which allows you to embed a specific PROJ.4
string to be used as the PROJ.4 version of this WKT.

I believe this was first released in GDAL/OGR 1.4.0.  I hope it helps.

Best regards,
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