[postgis-users] Questions about using SRID not -1
ibrahim saricicek
ibrahimsaricicek at gmail.com
Wed Jan 20 23:07:52 PST 2010
Hi;
No you can change projection any time you want, the point on your table is;
You have objects in different projections but in one table. You have to find
which objects are 4326 projection, and which are not...
Another method may be;
Select st_xmin(the_geom), st_ymin(the_geom) from mypoints
if the coordinates differ from -->
Longitude
180 W = -180
180 E = 180
Latitude
90 N = 90
90 S = -90
Namely your x not between -180 and 180 and y not between -90 and 90, the
objects are in an another projection.
I mean firstly try to differ different projected objects..
Regards,
IBO...
On Thu, Jan 21, 2010 at 2:01 AM, Oscar Zamudio <cmntlk at gmail.com> wrote:
> 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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