[GRASS-user] adding a datum to the GRASS database

[Markus Neteler]

Hi Ali,

On Fri, Nov 16, 2012 at 9:05 PM, Ali Swanson <swanson.ali at gmail.com> wrote:
> Hi all -
> I'm brand new to GRASS (though have basic familiarity with ArcInfo).

welcome :)

> I work
> in a datum that apparently isn't contained in the basic GRASS library --
> from what I've uncovered searching this list & the general web, I need to
> add my datum by going to the $GISBASE/etc/datum.table and appending this
> text:
>
> The Arc 1960 datum; source: EPSG database
> arc60 "Arc 1960" clark80 dx=-160 dy=-6 dz=-302

Which EPSG code is that? EPSG 4210, this one?

epsg_tr -pretty_wkt 4210
GEOGCS["Arc 1960",
    DATUM["Arc_1960",
        SPHEROID["Clarke 1880 (RGS)",6378249.145,293.465,
            AUTHORITY["EPSG","7012"]],
        TOWGS84[-160,-6,-302,0,0,0,0],
        AUTHORITY["EPSG","6210"]],
    PRIMEM["Greenwich",0,
        AUTHORITY["EPSG","8901"]],
    UNIT["degree",0.0174532925199433,
        AUTHORITY["EPSG","9122"]],
    AUTHORITY["EPSG","4210"]]

It should be there. You can use the Location Wizard to select this
EPSG code.

BUT: I just tried and the datum is not recognised:

g.proj -w
GEOGCS["clark80",
    DATUM["unknown",
        SPHEROID["Clarke_1880",6378249.145,293.465]],
    PRIMEM["Greenwich",0],
    UNIT["degree",0.0174532925199433]]

Do these tickets strike back?
http://trac.osgeo.org/grass/ticket/1452
http://trac.osgeo.org/grass/ticket/1748

Markus