[postgis-users] Reprojecting a PostGIS database

Reid Priedhorsky reid at umn.edu
Mon Feb 5 12:16:42 PST 2007


Hi folks,

I have a PostGIS database which is currently in a Plate Carree 
projection (EPSG 4326); this looks significantly distorted, and so we'd 
like to change the projection we show to users to something less 
distortionary. This brings up two questions:

1. Is it better to reproject the database once and for all, or to leave 
it in 4326 and reproject on the fly? If the former, how can I do that?

2. How does one intelligently choose a projection from the thousands 
stored in spatial_ref_sys? Currently, we've got data from only the 
Minneapolis-St. Paul metro area and have no plans to expand, but we 
could grow beyond that eventually. Also, it would be nice if map units 
stayed within the range (-180, 180) which would allow us to minimize 
changes to other parts of our application.

Any help, pointers to resources, or suggestions would be very much 
appreciated.

Thanks,

Reid