[postgis-users] newbie postgis and google maps question

[Paul Ramsey]

"Geographic Coordinates", "Longitude / Latitude", "Unprojected" ?

P.

On Jan 20, 2008, at 8:07 PM, Sam Boggess wrote:

>
> Thank you so much!  I'll try transforming it at the shp2pgsql stage.
>
> In ArcMap does 4326 have a name?  I can't find it?
>
>
>
> Paul Ramsey wrote:
>>
>> 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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