[gdal-dev] is Antarctic Polar Stereographic (EPSG:3031) properly handled by GDAL?

[Even Rouault]

Daniele,

I suggest you file a Trac ticket on this with the following info. From a first
review, it seems that libgeotiff doesn't deal with the EPSG projection method
9829 used by EPSG:3031, aka "Polar_Stereographic (variant B)" according to
http://javadoc.geotools.fr/2.4/org/geotools/referencing/operation/projection/Stereographic.html.
I'm not sure if OGRSpatialReference is ready for that variant B of Polar
Stereographic. The page mentions a "standard_parallel_1" parameter that testepsg
doesn't show.

I've tried the following patch (assuming, maybe wrongly, that projection 9829
could be used an alias of 9810) on an image generated by "gdal_translate -a_srs
EPSG:3031 src.tif dst.tif" and it helps a bit. The projection is retrieved but
the parameters are all 0, so there are maybe other bits missings or it might
also be a problem in the write part of libgeotiff. If it comes from a non-GDAL
based software, attaching your geotiff image () or a link to it might also help.

$ svn diff frmts/gtiff/libgeotiff/
Index: frmts/gtiff/libgeotiff/geo_normalize.c
===================================================================
--- frmts/gtiff/libgeotiff/geo_normalize.c      (révision 17587)
+++ frmts/gtiff/libgeotiff/geo_normalize.c      (copie de travail)
@@ -998,6 +998,7 @@
         return( CT_ObliqueStereographic );

       case 9810:
+      case 9829:
         return( CT_PolarStereographic );

       case 9811:

Needs a projection expert to sort that out I think.

Best regards,
Even

Selon Daniele Romagnoli <daniele.romagnoli at geo-solutions.it>:

> Hi list,
> I'm working on a geotiff image which is projected as EPSG:3031 (Antarctic
> Polar Stereographic).
> When running the last fwtools's gdalinfo, I get the following:
>
> Coordinate System is:
> PROJCS["WGS 84 / Antarctic Polar Stereographic",
>     GEOGCS["WGS 84",
>         DATUM["WGS_1984",
>             SPHEROID["WGS 84",6378137,298.2572235630016,
>                 AUTHORITY["EPSG","7030"]],
>             AUTHORITY["EPSG","6326"]],
>         PRIMEM["Greenwich",0],
>         UNIT["degree",0.0174532925199433],
>         AUTHORITY["EPSG","4326"]],
>     UNIT["metre",1,
>         AUTHORITY["EPSG","9001"]],
>     AUTHORITY["EPSG","3031"]]
>
> It seems that the projection part is missing (taking a look here:
> http://spatialreference.org/ref/epsg/3031/prettywkt/)
> Also trying to run a gdal_translate specifying -a_srs EPSG:3031 the
> projection definition of the newly created tiff is still missing.
> Does anyone has additional information on that topic?
>
> Thank you very much.
> Regards,
> Daniele
>
> --
> -------------------------------------------------------
> Eng. Daniele Romagnoli
> Software Engineer
>
> GeoSolutions S.A.S.
> Via Carignoni 51
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>
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>
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>
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