[postgis-users] Adding a custom projection

[Pavel Iacovlev]

Thank you for making it clear Nicolas. I added my countries projection to
Postgis and it works like a charm, will leave some info about MOLDREF 99 and
how to define it in case someone needs it.

Here is the SQL query to add MOLDREF 99 into postgis::

INSERT INTO public.spatial_ref_sys (srid, auth_name, auth_srid,
srtext, proj4text) VALUES (
100099
,'EPSG'
,100099
,'PROJCS["MOLDREF99",GEOGCS["MOLDREF99",DATUM["European_Terrestrial_Reference_System_1989",SPHEROID["GRS1980",6378137,298.257222101],TOWGS84[0,0,0,0,0,0,0]],PRIMEM["Greenwich",0],UNIT["degree",0.01745329251994328],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",28.4],PARAMETER["scale_factor",0.99994],PARAMETER["false_easting",200000],PARAMETER["false_northing",-5000000],UNIT["metre",1]'
,'+proj=tmerc +lat_0=0 +lon_0=28.4 +k=0.999940 +x_0=200000
+y_0=-5000000 +ellps=GRS80 +towgs84=-O,0,0,0,0,0,0 +units=m +no_defs'
);

more details about MOLDREF 99 can be found in my blog article:
http://iap.md/blog/detailed/id/9

On Mon, Dec 8, 2008 at 1:17 PM, Nicolas Ribot <nicky666 at gmail.com> wrote:

> > Good day all
> >
> > My country has the following coordinate system MOLDREF 99:
> > # MOLDREF 99
> > <100099> +proj=tmerc +lat_0=0 +lon_0=28g24m +k=0.99994 +x_0=200000
> > +y_0=-5000000 ellps=GRS80 +units=m +no_defs
> >
> > This is proj4 definition, now I need to add this projection to Postgis
> and I
> > don't understand some parameters like:
> >
> > AUTHORITY - ?
>
> Hi Pavel,
>
> As postgis uses Proj4 to perform transformation operations, the useful
> entries in spatial_ref_sys table is SRID and proj4text.
>
> Authority is supposed to be the name of the Reference authority that
> delivered/defined the projection (that could be the name of the
> official geographic institute in your country, for instance). It is
> used for informational purpose only.
>
> >
> > UNIT["degree",0.01745329251994328,AUTHORITY["EPSG","9122"]] - ?
> > PARAMETER["scale_factor",0.9999] - this is "k" i guess , correct ?
>
> Yes
>
> > PRIMEM - I know what datum and projections are, what does PRIMEM stands
> for
> > ?
>
> It stands for Prime Meridian, (Greenwich, Paris, ...) The reference
> for longitude origin.
>
> Nicolas
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>



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