st_area returns in the same units as the input data. So data in 4326 is
degrees and you numbers are in degrees squared. If you want the number
in meters or feet then project then into an appropriate UTM or equal
area projection.
-Steve
On 3/24/2012 11:48 AM, Eric Ladner wrote:
I've got some building outlines that I'm pretty sure I've worked with
before. They are all srid 4326 (lat/lon), converted from a SHP file.
ST_Area returns extremely small numbers for any of the buildings.
It's almost like it's looking at the data like they are absolute
numbers instead of lat/lon.
Thoughts?
As an example:
select st_npoints(the_geom), st_srid(the_geom), st_summary(the_geom),
st_area(st_transform(the_geom,4326)) from buildings;
st_npoints | st_srid | st_summary |
st_area
------------+---------+----------------------------------+----------------------
5 | 4326 | | 9.7305773438805e-09
: MultiPolygon[BS] with 1 elements
: Polygon[] with 1 rings
: ring 0 has 5 points
:
5 | 4326 | | 1.1065881433403e-08
: MultiPolygon[BS] with 1 elements
: Polygon[] with 1 rings
: ring 0 has 5 points
:
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