[gdal-dev] How get EPSG code from an OGRSpatialReferenceH?

[David Strip]

It's my recollection from a question I posted here  a little over a year
ago that except for a few special cases, autoIdentifyEPSG only works if
there is an authority node providing the EPSG. Hopefully someone will
give you an authoritative answer. I believe GeoTools has the capability
to find the EPSG from the WKT, but I have no idea how to interface to that

On 8/28/2014 8:42 PM, Nik Sands wrote:
> Hi devs,
>
> What is the correct way to extract the EPSG code from an OGRSpatialReferenceH ?
>
> Currently I'm finding that the following works only for SRS of some images and not others:
>
> 	const char *charAuthType = OSRGetAttrValue(gdal.srcSRS, "AUTHORITY", 0);
> 	const char *charSrsCode = OSRGetAttrValue(gdal.srcSRS, "AUTHORITY", 1);
>
> However, there is no "AUTHORITY" node in some SRSs so it doesn't work for those images.  To cater for this, I'm trying to explicitly set the authority node using:
>
> 	OSRAutoIdentifyEPSG(gdal.srcSRS);
>
> But this fails with OGRERR_UNSUPPORTED_SRS (even when it is an SRS that GDAL recognises and uses well).
>
> So I'm stumped... how do I reliably determine the EPSG for an OGRSpatialReferenceH?
>
> Cheers,
> Nik.
>
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