[fdo-internals] PostGIS and Spatial context question

Mateusz Loskot mateusz at loskot.net
Wed Apr 9 18:50:27 EDT 2008

Bruno Scott wrote:
> PostGIS store its metadata in a table called geometry_columns For
> each of the spatialy enabled table we can specify a srid in this 
> geometry_columns table. For PostGIS this srid is an integer that
> reference a coordinate system definition in a table called
> spatial_ref_sys.
> The actual implementation of the PostGIS provider that Matheus did,
> return something like PostGIS_SRID as spatial context ( where SRID is
> replaced by the proper srid integer )


yes, that's right.
There is no concept like spatial reference system name in PostGIS, so
I decided to use that scheme to fill that gap.

> When i try to connect to PostGIS within Map2008 or Map2009, Map
> display an "Unknown" spatial context see screen capture 
> http://www.nabble.com/file/p16581335/AddDataToMap.jpg
> Is it normal? How map is suppose to know how to translate a PostGIS
> srid to a Mentor one?

Name is just user level information. The engine and clients are supposed 
to use WKT attached to every instance of spatial context.

Mateusz Loskot

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