Hi Ravi,
Sounds like you are dealing with point features, with a single coordinate pair.
So if that is case this should help.
If you know the coordinate system they are in, you can tell Postgis to use that
& transform the points to a lat/long geometry, as below. Posdtgis cannot detect
a coordinate system, it generally needs to be told what the coordinate system
is, unless the values are already geometries with a defined SRID. In which case
you cal either
\d <table> & note the the value set for the ST_srid() constraint, or you can
try:
select ST_srid(geom) from table limit 1;
Given a table called tab with columns E & N, in a projection with SRID of 1234
(for example)
To create the geometry column:
select ST_AddGeometryColumn('','tab','geom',4326,'POINT',2);
To populate it:
update tab set
geom=ST_Transform(ST_Setsrid(ST_Makepoint(E, N), 1234), 4326);
What this does is: make a point geometry from your E/N values, set this to the
appropriate projection, convert the coordinates to lat/lon/WGS84 (SRID=4326)
and set the geom value for each record to the result.
To find the SRID for your E/N coordinate system your E/N values are in, I
suggest you visit:
http://www.spatialreference.org/
to find the EPSG code, which is generally the SRID used by Postgis to identify
a projection.
HTH,
Brent Wood
--- On Sat, 2/12/11, Ravi <[email protected]> wrote:
From: Ravi <[email protected]>
Subject: [postgis-users] E-N to Long Lat
To: "postgis" <[email protected]>
Date: Saturday, February 12, 2011, 7:35 PM
Got a data base of Eastings and Northings
which is the simplest way to
1. Detect the projection, as I know where they belong
2. Turn the table (in PostGIS) to Long Lat
Ravi
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