[postgis-users] newbie postgis and google maps question

[Paul Ramsey]

Mercator <> EPSG:4326

4326 is geographic coordinates on a WGS84 spheroid.  Mercator is  
projected coordinates still.

Either upload your shape file in the original coordinates, and then  
transform in PostGIS:

shp2pgsql -D -i -s 2992 shpfile.shp tablename
select ST_AsText(ST_Transform(the_geom, 4326)) from tablename

Or do you ArcMap stuff but output in 4326 to start with.

Good luck!

P.

On Jan 20, 2008, at 7:39 PM, Sam Boggess wrote:

>
> The original shape file, that I got from the Oregon Forestry  
> Department, had
> this projection:
>
> Data Type: Shapefile Feature Class
> Shapefile: Z:\FSN\seedzone_pre1996\sz_orwa_pre1996.shp
> Geometry Type: Polygon
>
> Projected Coordinate System:  
> NAD_1983_Oregon_Statewide_Lambert_Feet_Intl
> Projection: Lambert_Conformal_Conic
> False_Easting: 1312335.95800525
> False_Northing: 0.00000000
> Central_Meridian: -120.50000000
> Standard_Parallel_1: 43.00000000
> Standard_Parallel_2: 45.50000000
> Latitude_Of_Origin: 41.75000000
> Linear Unit: Foot
>
> Geographic Coordinate System: GCS_North_American_1983
> Datum: D_North_American_1983
> Prime Meridian: 0
> Angular Unit: Degree
>
>
> So I projected that into mercator in ArcMap:
>
> Data Type: Shapefile Feature Class
> Shapefile: Z:\FSN\seedzone_pre1996\sz_orwa_pre1996_Project.shp
> Geometry Type: Polygon
>
> Projected Coordinate System: World_Mercator
> Projection: Mercator
> False_Easting: 0.00000000
> False_Northing: 0.00000000
> Central_Meridian: 0.00000000
> Standard_Parallel_1: 0.00000000
> Linear Unit: Meter
>
> Geographic Coordinate System: GCS_WGS_1984
> Datum: D_WGS_1984
> Prime Meridian: 0
> Angular Unit: Degree
>
>
> I then used shp2pgsql to add this to my database:
>
> SELECT AddGeometryColumn('members_oldzone', 'poly', 4326,  
> 'MULTIPOLYGON',
> 2);
> ALTER TABLE "members_oldzone" ALTER "poly" SET NOT NULL;
> CREATE INDEX "members_oldzone_poly_id" ON "members_oldzone" USING  
> GIST (
> "poly" GIST_GEOMETRY_OPS );
>
>
>
> Paul Ramsey wrote:
>>
>> Your original data is probably not 4326. Do you have any clue what
>> projection it is in? Where did you get it from?
>>
>> P
>>
>> On Jan 20, 2008, at 7:02 PM, Sam Boggess wrote:
>>
>>>
>>> Hello,
>>>
>>> I'm new to PostGIS and this has to be a cakewalk for
>>> you experienced users, but your help would be greatly  
>>> appreciated.  I
>>> have a PostGIS enabled database that contains polygon data from a
>>> shapefile using SRID 4326.  All I want to do at this point is mark  
>>> the
>>> centers of all of my polygons in Google Maps.  I've written my
>>> query, and it works great:
>>>
>>> select astext(centroid(poly))
>>> from zones
>>>
>>> returns (a bunch of):
>>> POINT(-13057223.7425678 6208110.75868711)
>>>
>>> However, I have no idea what to do with this point data.  Google  
>>> maps
>>> expects lat and long; how can i convert this?  In another forum a  
>>> user
>>> suggested dividing by 10, but that's a point in Northern Canada,
>>> this point
>>> should be in NE Washington State.
>>>
>>> Any Help would be greatly appreciated
>>> -- 
>>> View this message in context:
>>> http://www.nabble.com/newbie-postgis-and-google-maps-question-tp14989995p14989995.html
>>> Sent from the PostGIS - User mailing list archive at Nabble.com.
>>>
>>> _______________________________________________
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>>
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>
> -- 
> View this message in context: http://www.nabble.com/newbie-postgis-and-google-maps-question-tp14989995p14990735.html
> Sent from the PostGIS - User mailing list archive at Nabble.com.
>
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