[postgis-users] Re: [Fwd: Error in PostGIS spatial_ref_sys table?]

[Kevin Neufeld]

Hi Martin,

I've forwarded your observation to the PostGIS list, where someone will 
verify and post the bug in our PostGIS bug tracker.

Thanx,
Kevin

Jody Garnett wrote:
>
>
> ------------------------------------------------------------------------
>
> Subject:
> Error in PostGIS spatial_ref_sys table?
> From:
> Martin Desruisseaux <martin.desruisseaux at geomatys.fr>
> Date:
> Wed, 19 Mar 2008 20:00:46 +0100
> To:
> pramsey at refractions.net
>
> To:
> pramsey at refractions.net
> CC:
> jgarnett at refractions.net, Mickael.Treguer at ifremer.fr, Vincent 
> Heurteaux <vincent.heurteaux at geomatys.fr>
>
>
> Hello Paul
>
> The spatial_ref_sys table in PostGIS defines EPSG:27572 ("NTF (Paris) 
> / Lambert zone II") with the following element in the "srtext" column:
>
>     PRIMEM["Paris", 2.33722917]
>
> it should be
>
>     PRIMEM["Paris", 2.5969213]
>
> because the angle is supposed to be express in gradiants, not in 
> degrees (the former is the correct longitude but in degrees. The later 
> is the same longitude in gradiants).
>
> Quoting the OGC specification: "If the PRIMEM clause occurs inside a 
> GEOGCS, then the longitude units will match those of the geographic 
> coordinate system".
>
> http://geoapi.sourceforge.net/snapshot/javadoc/org/opengis/referencing/doc-files/WKT.html#PRIMEM 
>
>
> It doesn't have any impact on the transformations performed by PostGIS 
> since it relies on Proj4 and the definition in the "proj4text" is 
> correct. But it impact the transformations performed by GeoTools when 
> the later try to read the definition from the "srtext" column in a 
> PostGIS database.
>
> The same probably applies to other CRS around EPSG:27572 (there is 
> Lambert Zone I, Lambert Zone III, etc. I didn't checked them).
>
> Not a blocker issue for us - I have implemented a workaround. Just for 
> letting you know.
>
>     Regards,
>
>         Martin