[postgis-users] Re: SRID for USA_Lambert_Conformal_Conic

[P Kishor]

Right then. So, I have to insert an entry for my SRS in the
spatial_ref_sys table. Actually, I am surprised something like
"USA_Contiguous_Lambert_Conformal_Conic" is not already there... I was
assuming this was one of the common USA projections.

In any case, I have the srtext nonsense. How do I "discover" the srid,
auth_name, auth_srid, and proj4text for it? I am assuming I can't just
make stuff up here.

Follow-up question -- when I am able to add a row to the
spatial_ref_sys table, then what? Do I have to actually transform
(project) my datasets into this projection, and store them like that,
or do I apply this projection on the fly whenever I do any SQL
operation on them?

On 8/19/06, Dylan Beaudette <dylan.beaudette at gmail.com> wrote:
> ja.
>
> On 8/19/06, P Kishor <punkish at eidesis.org> wrote:
> > On 8/19/06, Dylan Beaudette <dylan.beaudette at gmail.com> wrote:
> > > Do you have any of the parameters associated with the Lambert
> > > conformal conic projection? You will need these in order to add an
> > > entry to the spatial_ref_sys table, with a custom SRID.
> >
> > Well, I do have the entire SRTEXT. Is that what you meant?
> >
> >
> > >
> > > you can get more information on your original file with a tool like ogrinfo .
> > >
> > > Cheers,
> > >
> > > On 8/19/06, P Kishor <punkish at eidesis.org> wrote:
> > > > Actually, I should explain this a bit further --
> > > >
> > > > (a) I had a Shapefile in USA_Lambert_Conformal_Conic that I imported
> > > > into PostGIS using the shp2pgsql, psql dance. Whatever I did, its SRID
> > > > is set to -1.
> > > >
> > > > (b) I created another dataset from lon/lat explicitly setting its SRID to 4326.
> > > >
> > > > Of course, now I can't do any geometrical analysis on these two
> > > > because they are in different spatial references. Ideally, I want to
> > > > convert my (b) dataset, the points that are in 4326, to the same srs
> > > > as (a) dataset, namely USA_Lambert_Conformal_Conic.
> > > >
> > > > Hence my question.
> > > >
> > > > Many thanks in advance.
> > > >
> > > > On 8/19/06, P Kishor <punkish at eidesis.org> wrote:
> > > > > This is a topic I know very little about. Where do I learn more about
> > > > > SRIDs, and more specifically,
> > > > >
> > > > > 1. how do I find SRID for USA_Lambert_Conformal_Conic; and
> > > > > 2. use that to change a dataset (project? is that the word wrt SRIDs?)
> > > > >


-- 
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/