[postgis-users] Projection for Calculating Area

Norman Vine nhv at cape.com
Thu Feb 21 09:57:53 PST 2008

Travis Kirstine writes:
> We have been developing a web mapping application using google maps as
> the front end interface with a postgis backend.  Using this
> application the user can draw a bounding box in google maps and the
> coordinates are then passed to postgis.  With postgis we then perform
> a query on the polygons stored in the postgis database to return the
> area using  ST_Intersection, ST_Transform (usually to UTM) and finally
> ST_Area.  The application works great but the problem is  that since
> we are trying to work on a global scale it is difficult to determine
> what projection (EPSG) to transform the data to calculate an accurate
> area since our data is in EPSG:4326 and returns decimal degrees.  We
> can easily transform the query results to a UTM or a Albers projection
> however the results can be inaccurate since the user may select
> multiple zones or hemispheres when view the map at a global scale.  Is
> there a accurate global projection for calculating area?

This paper discusses the problem and describes its solution in a non 
FOSS system

I see this but haven't read it



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