[postgis-users] srid

[Andy Anderson]

SRID is an index into the table of datums/projections/coordinate  
systems that PostGIS maintains; the commands to create that table are  
in the file spatial_ref_sys.sql that comes with the distribution.

If you want to build your own transformation, you could start with one  
of the listed INSERT statements that matches the type of projection,  
and change the coordinates to match your interest. Then add it to the  
existing table with an SRID that isn't being used.

By the way, the SRID is part of the EPSG standard <http://en.wikipedia.org/wiki/SRID 
 >, so keep that in mind for future potential conflicts.

-- Andy

On May 25, 2008, at 12:21 PM, Bob Pawley wrote:

> Hi
>
> I am attempting to learn Postgis to use as a geometric tool rather  
> than a geographic tool.
>
> The function ST_Transform(geometry, integer)  seems to be  
> potentially quite useful.
>
> Apparently, the integer required is the new coordinates referenced  
> by the srid. Is there some way of building a spatail reference table  
> in which I can enter my coordinates that the ST_Transform function  
> will recognize. My first simplistic attempt (entering a coordinate  
> with an id) didn't work.
>
> Bob
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