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

[Ethan Alpert]

not possible...I have 300K spatial records...
 

	-----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 4:18 PM
	To: 'PostGIS Users Discussion'
	Subject: RE: [postgis-users] Computing area in km^2 from 4326
geometries
	
	

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

	 

	--Craig

	 

	 

	
________________________________


	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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