[postgis-users] Re: SRID for USA_Lambert_Conformal_Conic

[P Kishor]

On 8/20/06, Matthew Perry <perrygeo at gmail.com> wrote:
> On 8/20/06, P Kishor <punkish at eidesis.org> wrote:
> > Humour me. SetSRID(geometry, integer) and Transform(geometry, integer)
> > seem/sound almost the same. Is SetSRID more permanent, while Transform
> > is more for on the fly retreival of data?
>
> SetSRID defines what the current spatial reference of the existing
> geometry is. No actualy transforming/reprojecting will be done.
>
>  Transform reprojects the geometry from it's native spatial reference
> (ie as defined by SetSRID) to another.


a'ite then... in my language, SetSRID is "metadata" while Transform
actually "mutates" the data. Now to my original question -- I have two
datasets in existing SRIDs (actually one of them is -1, and the other
is 4326). I want to convert them both to my ESRI defined 102005
(USA_Contiguous_Lambert_Conic) for which I have INSERTed an entry in
the spatial_ref_sys table. Let's take one of the datasets called, say,
'my_table'

What do I do now? Do I
  UPDATE my_table
  SET the_geom = Transform(the_geom, 102005)

or do I
  UPDATE geometry_columns
  SET srid = 102005
  WHERE f_table_name = 'my_table'

or both, or something else?

Many thanks y'all for holding my hand here. All this is not difficult,
just a bit opaque for now...

-- 
Puneet Kishor http://punkish.eidesis.org/
Nelson Inst. for Env. Studies, UW-Madison http://www.ies.wisc.edu/
Open Source Geospatial Foundation https://edu.osgeo.org/