[postgis-users] Questions about using SRID not -1

[Oscar Zamudio]

Ben,
I tried your intruction:

UPDATE mypoints SET the_geom = ST_SetSRID(the_geom,4326);

But I got:

ERROR:  Operation on two GEOMETRIES with different SRIDs

Regards,
Oscar

On Sat, Jan 16, 2010 at 10:48 PM, Ben Madin
<lists at remoteinformation.com.au>wrote:

> Oscar,
>
> you have a couple of options as I see it. In Postgres you could just update
> the geometries first.
>
> > UPDATE mytable SET the_geom = ST_SetSRID(the_geom,4326);
>
>
> And for next time, assuming your data originally had some sort of
> coordinate system (and it must have if it was spatial data), you can /
> should use the -s flag in shp2pgsql to provide 'SRID awareness'
>
> In your case, I would suggest -s 4326.
>
> ie (using -d to drop and replace existing table
>
> $ shp2pgsql -s 4326 -d myshapefile myoldtablename | psql mydatabase
>
>
> In geometry terms, I think it is unlikely that your data was stored
> (spatially) as sexagesimal degrees, although it may be displayed as such in
> your GIS.
>
> cheers
>
> Ben
>
>
>
>
>
> On 17/01/2010, at 2:54 , Oscar Zamudio wrote:
>
> > Hi,
> > I'm have problems to transform my spatial data to UTM. First, this
> instruction works OK:
> >
> > SELECT ST_Transform(ST_GeomFromText('POINT(0.0 20)',4326),22171) from
> mypoints
> >
> > No matter if such a sentence has no meaning on what I tryin to do.  But
> when I did the same with my own points:
> >
> > SELECT ST_Transform(mypoints.the_geom,22171) from mypoints
> >
> > I get the following error:
> > ERROR: Input geometry has unknown (-1) SRID
> > SQL state: XX000
> >
> > Ok, when I insert my points in my spatial enabled database I used:
> >
> > INSERT INTO mydistance ( the_geom, the_name ) VALUES (
> ST_GeomFromText('POINT(-58.0 0.0)'), 'Punto 1-1');
> >
> > without no spatial reference system explicit so I guess the SRID is set
> to "unknown" i.e. -1.  Then naively I created a new column named srid for my
> table and put the right value of SRID for all my data which is 4326 (WGS84,
> sexagesimal degrees lat lon) in that column but still I get the same error.
> After that I created a constraint between this new srid column and the srid
> column from the spatial_ref_sys table but nothing happened, the error is
> still there.
> > It's important to me to solve this issue because all my spatial data was
> loaded from shapefiles without SRID awareness so they don't have any SRID
> column. I don't want to reload data changing this so I need a method to
> alter the tables in such a way to add this new srid column to them that is
> well related to the spatial context.
> > Thanks and regards,
> > Oscar
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>
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