[Proj] proj-datumgrid-1.4 issued

[Paul Kelly]

On Tue, 22 Jul 2008, Frank Warmerdam wrote:

> Richard Greenwood wrote:
>> On Mon, Jul 21, 2008 at 7:59 PM, Frank Warmerdam <warmerdam at pobox.com> 
>> wrote:
>>> Folks,
>>> 
>>> I have uploaded a new version of the datum grid shift file collection that
>>> includes the ntf_r93.gsb shift file.  Richard, perhaps you could more 
>>> fully
>>> explain how this grid shift file works?
>> 
>> I wish I could, but I'm still struggling with the .lla files!
>
> Rich,
>
> Sorry, I actually mean Richard Didier who added this .gsb file in PROJ.  :-)

I imagine this would be similar to my france.gsb file to convert between 
the French NTF and RGF93 datums, documented in detail here:
http://www.stjohnspoint.co.uk/gis/france.htm
so perhaps that page would be of interest?

Paul

(BTW I never pressed to have it included in GRASS or PROJ.4 as I wasn't 
sure about the licence/legal status of the tables I derived it from.)