[postgis-users] Newbie questions: SRIDs, function return values

[Andy Anderson]

On Wed, May 14, 2008 at 3:13 PM, David Jantzen <david at culturemob.com>  
wrote:
>  How do I find the real SRID if it is?

No doubt there's a better way, but I search through the file  
spatial_ref_sys.sql that comes with PostGIS to find the description  
that matches the information provided with the data.

Unfortunately geographic coordinate data (lat/long) is often  
published without a reference to its datum (underlying model of the  
Earth). If it comes out of a GPS it's probably WGS84, but this is  
only one of many "standards" that you might encounter (NAD83 and  
NAD27 are also common in the U.S.).

-- Andy