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

[Oscar Zamudio]

Hi everybody.
I had no success with any of the recipes received here.
Could it be that a table with data loaded without SRID explicit value has no
chance of being updated later to the right one?
Regards,
Oscar


On Sun, Jan 17, 2010 at 1:08 PM, Oscar Zamudio <cmntlk at gmail.com> wrote:

> 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
>> > _______________________________________________
>> > postgis-users mailing list
>> > postgis-users at postgis.refractions.net
>> > http://postgis.refractions.net/mailman/listinfo/postgis-users
>>
>> _______________________________________________
>> postgis-users mailing list
>> postgis-users at postgis.refractions.net
>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20100118/436dbece/attachment.html>