[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
http://geodyssey.com/papers/ggelare.html
I see this but haven't read it
http://portal.acm.org/citation.cfm?id=302304.302315
HTH
Norman
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