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

[Oscar Zamudio]

Hi,
I tried:

UPDATE  mypoints SET the_geom_4326=transform(the_geom,4326)

But again I got:

ERROR:  Input geometry has unknown (-1) SRID

It seems that once the data is without explicit SRID, they cannot
be processed later for asigning a proper SRID.
It is strange at first sight....but I'm a newbie so I don't know much about
this.
Regards,
            Oscar

On Tue, Jan 19, 2010 at 6:27 AM, ibrahim saricicek <
ibrahimsaricicek at gmail.com> wrote:

> Hi,
>
> Your table include objects, more than one projection.. So if there is any
> object in different projection you can't set your table projection to
> 4326...
>
> can you try this!!
>
> Create a new geometry column "the_geom_4326"
>
> then run this
>
> UPDATE  table_name SET the_geom_4326=transform(the_geom,4326),
>
> then use ST_SetSRID for the new column...
>
> REgards,
> ibo...
>
>
> On Mon, Jan 18, 2010 at 7:23 PM, Oscar Zamudio <cmntlk at gmail.com> wrote:
>
>> 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
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>>
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