[postgis-users] custom EPSG codes?

Robert Coup robert.coup at koordinates.com
Mon Jul 19 14:10:14 PDT 2010

On Tue, Jul 20, 2010 at 8:06 AM, chrispg <chrisemberson at hotmail.com> wrote:

> I have data in British Nat Grid that I would like to load into postgis.
> Normally I would use EPSG:27700 to do this no problem, but the coordinates
> are to decimetre precision, not metre, so 27700 is out by a factor of 10. I
> can edit the spatial_ref_sys.sql to generate a custom projection file, but
> then performing any queries on that using the PROJ4 libraries are a problem
> as it is not recognised. Has anybody come across this before?

Maybe add your new projection to the proj4 library as well?

Copy the 27700 line from /usr/share/proj/epsg to /usr/share/proj/my using a
new number (eg. 927700), set the same number in spatial_ref_sys, and then
use +init=my:927700 with proj4, and srid=927700 in postgis...

If decimeters are regularly used in datasets, consider submitting to
http://www.epsg.org/ to get assigned an "official" number.

Rob :)
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