[gdal-dev] how should SpatialReference::EPSGTreatsAsLatLong work?

Kyle Shannon KShannon at gcs-research.com
Thu Mar 15 11:15:37 EDT 2012


Jachym,
Like Etienne said, 3035 is projected.  I believe 4326 is not returning true because the OGC (or proj or whatever is the definitive internal format) makes no reference to an axis and according to the docs:

'''Note that coordinate systems with an EPSG code and no axis settings will be assumed to not be lat/long.'''

kyle at home$ gdalsrsinfo -o proj4 epsg:4326
'+proj=longlat +datum=WGS84 +no_defs '

and wkt:

GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","632
6"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY
["EPSG","4326"]]

My best guess anyway.

kss

-----Original Message-----
From: gdal-dev-bounces at lists.osgeo.org [mailto:gdal-dev-bounces at lists.osgeo.org] On Behalf Of Etienne Tourigny
Sent: Thursday, March 15, 2012 7:26 AM
To: Jachym Cepicky
Cc: gdal-dev at lists.osgeo.org
Subject: Re: [gdal-dev] how should SpatialReference::EPSGTreatsAsLatLong work?

The reference for EPSGTreatsAsLatLong  is "This method returns TRUE if EPSG feels this geographic coordinate system should be treated as having lat/long coordinate ordering."

However, EPSG 3035 is not a geographic coordinate system, but a projected one (Lambert Azimuthal Equal Area).

Etienne

On Thu, Mar 15, 2012 at 6:00 AM, Jachym Cepicky <jachym.cepicky at gmail.com> wrote:
> Hi,
>
> I'm trying to figure out, how OGRSpatialReference::EPSGTreatAsLatLong 
> is supposed to be working -> I'm not able to get any proper result.
>
> I'm playing with the python interface at this place (and assume, C-api 
> would work similar way).
>
> When I create OGRSpatialReference and import it from EPSG with the 
> code 4326, I would say, EPSGTreatAsLatLong should return True:
>
> from osgeo import osr
> sr = osr.SpatialReference()
> sr.ImportFromEPSG(4326)
> sr.EPSGTreatAsLatLong()
> 0
>
> Same applies, when trying the same with e.g. EPSG:3035
>
> sr.ImportFromEPSG(3035)
> sr.EPSGTreatAsLatLong()
> 0
>
> Both do have (accordi ng to http://epsg-registry.org/) north,east axis 
> order, so I would asssume EPSGTreatAsLatLong would return True
>
> Could anybody give me a hint, what am I doing wrong?
>
> Thanks
>
> Jachym
>
>
>
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