Hi Markus - Thanks for your prompt reply. Unfortunately, I think that my GRASS skills are faaaar below those of most other users. (I don't even know how to *find* the datum.table file to which I thought I was supposed to add the ARC1960 datum, or really understand your suggestions.) But! From your advice I was able to (I think) select the proper Arc1960 datum. I have done everything so far with the graphical interface, and was trying to select the Arc1960 (using location wizard) from the first menu choice (selecting from a list of coordinate system parameters) -- when I chose the second menu option (select EPGS code of spatial reference system), I believe I found it. Pretty basic, in the end. Thanks again!
On Sat, Nov 17, 2012 at 5:54 AM, Markus Neteler <[email protected]> wrote: > Hi Ali, > > On Fri, Nov 16, 2012 at 9:05 PM, Ali Swanson <[email protected]> > 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 >
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