[postgis-users] Converting UTM to lat/lon using Postgis

Guillaume Sueur no-reply at neogeo-online.net
Mon May 3 00:08:06 PDT 2010


Hi,

As you declared your input shapefile to be in 4326 (which is lat/lon), 
Postgis doesn't transform anything in your coordinates when you ask for 
lat/lon.
Try to set the proper SRID for Dubai Local Transverse Mercator using 
SELECT setSRID(the_geom,the_srid) FROM ult.test2;
Note that you may have to drop a constraint forcing your srid to be 4326 
first.

Regards,

Guillaume

On 03/05/2010 09:03, Mehmet Erkek wrote:
> Hi All,
>
> I havea a shape file which I imported it to a table called ‘test2’
> (using SRID=4326). I want to get centroids of geometries in lat/lon.
>
> Here is what I run:
>
> select ST_AsText( ST_Transform(centroid(the_geom),4326)) from ult.test2
> limit 5;
>
> and what I get:
>
> POINT(496597.996430787 2774798.21242881)
>
> POINT(496332.629887436 2793339.61534586)
>
> POINT(496302.627327975 2793317.82477318)
>
> POINT(496305.255261594 2793353.29646291)
>
> POINT(496241.538851096 2774826.65593589)
>
> So far all is fine except coordinates which are not latitude/longitude
>
> *_My question is : How can I convert/get these coordinates in lat/lon?_*
>
> This what I have in my prj file:
>
> PROJCS["Dubai Local Transverse Mercator
> (DLTM)",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",55.33333333333334],PARAMETER["Scale_Factor",1.0],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]
>
> And this is my postgis version: POSTGIS="1.3.6" GEOS="2.2.3-CAPI-1.1.1"
> PROJ="Rel. 4.7.1, 23 September 2009" USE_STATS
>
> I appreciate any help. Thank you.
>
> -------------------------------------------------------------------
>
> *Mehmet ERKEK***
>
> www.REIDIN.com <http://www.reidin.com/>
>
>
> This message is for the designated recipient only and may contain
> privileged, proprietary, or otherwise private information. If you have
> received it in error, please notify the sender immediately and delete
> the original. Any other use of the email by you is prohibited. Please
> Consider the Environment Before Printing This Email
>
>
>
> _______________________________________________
> postgis-users mailing list
> postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users



More information about the postgis-users mailing list