[postgis-users] Computing area in km^2 from 4326 geometries

[Craig Miller]

One rather blunt way would be to store your data in a projection that
accurately maintains area and is based in meters/kilometers.

 

--Craig

 

 

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From: Ethan Alpert [mailto:ealpert at digitalglobe.com] 
Sent: Tuesday, September 28, 2004 3:12 PM
To: PostGIS Users Discussion
Subject: RE: [postgis-users] Computing area in km^2 from 4326 geometries

 

I'm getting degrees^2 because my geometry is in lat/lon afaict.

 

-e

-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Craig
Miller
Sent: Tuesday, September 28, 2004 4:07 PM
To: 'PostGIS Users Discussion'
Subject: RE: [postgis-users] Computing area in km^2 from 4326 geometries

If the area function is returning square meters (depends on your projection)
then just divide the answer by 4046.896 to get kilometers.

 

All area functions are squared by definition.

 

--Craig

 

 

 


  _____  


From: Ethan Alpert [mailto:ealpert at digitalglobe.com] 
Sent: Tuesday, September 28, 2004 2:57 PM
To: PostGIS Users Discussion
Subject: [postgis-users] Computing area in km^2 from 4326 geometries

 

How does one compute areas in km^2? I was thinking something like
area2d(transform(the_geom,<someEPSG>)). 

How do others do this?

 

Thanks!

 

-e

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