[postgis-users] question on returning area size using st_area.

[Stephen Lee]

hi there,

i've just started using postgis, i have loaded a sample map of malaysia
using the following command:

F:\PROGRA~1\PostgreSQL\8.3\bin>shp2pgsql -c -s 4326
G:\Maps\Malaysia\Detailsmaps\state_region public.mal_state > state.sql

Shapefile type: Polygon
Postgis type: MULTIPOLYGON[2]

the projection file in the prj is as follow so I assume the SRID is 4326 :

GEOGCS["Lat Long
WGS84",DATUM["D_WGS84",SPHEROID["World_Geodetic_System_of_1984",6378137,298.257222932867]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]]

the map is successfully loaded and can be viewed using uDig. The problem
occurs when I tried to use the st_area command as state in the PostGIS
(1.3.3) manual (4.6.2.2). the sql statement i issue is:

SELECT
  ST_Area(the_geom)/10000 AS hectares
FROM mal_state
WHERE name = 'KELANTAN';

hectares
------------------
0.000122167591783352
(1 row)

is the return result measure in the unit of the WGS84 projection? if so how
can i change it to the correct measurement? i have attached my map file in
this email, can someone please shine some light? thanks in advance.

best regards,

Stephen
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