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ED50 Norway Offshore Spheroid Default Vallues

Ioannis.mag Global Mapper UserTrusted User
edited July 2010 in Projection Questions
Hi there,

I am setting up the projection in the GM model that I am building into UTM Z34 into ED50(Norway Offshore - N62).

I was wondering whether it will by default use the International (1924) Spheroid and not anything else?

The reason that I am asking is that when I click on the "Add Datum" button next to the Datum drop down menu I always come up to the Clarke 1866 option as the 1st one in the drop down menu at the next table which pops up.

Is Clarke 1866 the one that you get by default when you click on "Add Datum" at GM? Although if prior to that you go for any other datum?

Your page: specifically says that the Datum that I am using (ED50(Norway Offshore - N62)) is supported by the 1924 Spheroid.

I hope I am not getting my knickers in a twist here. All I am asking is whether GM will use the International (1924) Spheroid with ED50 Norway Offshore - N62 by default.

I think for a future version it would be good to be able to see the Spheroid that is being used at the Projection Settings Tab menu as well.

Thanks and Regards,


  • global_mapper
    global_mapper Administrator
    edited July 2010
    A datum is always defined to use a particular ellipsoid, so there is no need to select an ellipsoid in addition to a datum. The ED50 datum is defined to use the International 1909/1924 ellipsoid, so that is the ellipsoid that will be used for that datum, no need to select it specifically.

    The Add Custom Datum dialog just defaults the ellipsoid to the first one in the list, there's nothing special about Clarke 1866.

    Let me know if I can be of further assistance.


    Global Mapper Support
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