[Proj] Re: new 7 parameters

[massimodisasha]

wow !
great!
this is what i need :-) ,
thanks for your help !!!

Massimo.

Il giorno 23/ott/06, alle ore 18:02, proj-request at lists.maptools.org  
ha scritto:

> On Sat, Oct 21, 2006 at 07:41:47PM +0200, massimodisasha wrote:
>> hi,
>> i've 45 point of the (igm95) national italian grid of double points
>> in (wgs84 - gauss boaga R40)
>> (IGM is the italian's geographical military institute)
>>
>> all my points are distribuited in a small italian region.
>>
>> i've done a little algoritms in matlab language  for resolve the
>> Helmert linear sistem....
>> ...now i've a new set of 7 parameters for do a trasformation beetween
>> WGS and GB-R40.
>>
>> how can i use this new parameters in Grass ?
>
> When you define a new "location" (GRASS project), then
> select
> D Other projection
> to go into the user defined dialog.
>
> Then select
>
> Please specify projection name
> Enter 'list' for the list of available projections
> Hit RETURN to cancel request
>> tmerc
> Do you wish to specify a geodetic datum for this location?(y/n) [y]
>
> Please specify datum name
> Enter 'list' for the list of available datums
> or 'custom' if you wish to enter custom parameters
> Hit RETURN to cancel request
>> custom                                 <<<<--- !!
>
> Please specify ellipsoid name
> Enter 'list' for the list of available ellipsoids
> Hit RETURN to cancel request
>> international
>
> Please specify datum transformation parameters in PROJ.4 syntax.  
> Examples:
>         towgs84=dx,dy,dz        (3-parameter transformation)
>         towgs84=dx,dy,dz,rx,ry,rz,m     (7-parameter transformation)
>         nadgrids=alaska (Tables-based grid-shifting transformation)
> Hit RETURN to cancel request
>> towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68
> Parameters to be used are:
> "towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68"
> Is this correct?(y/n) [y]
>
> Enter Scale Factor at the Central Meridian  [1.0000000000]: 0.9996
> [...]
>
>
>
>> can i use it in the (r.proj/v.proj) grass command?
>
> Like this r.proj/v.proj use the datum.
>
> Shortcut: If you want to modify an existing location (not
> sure if that's a good idea since your data need to be reprojected),
> simply edit
> grassdata/<location>/PERMANENT/PROJ_INFO
> and substitute the old datum parameters with
>
> datum: rome40
> datumparams: towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68
>
> My PROJ_INFO looks like this:
> name: Transverse Mercator
> datum: rome40
> datumparams: towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68
> proj: tmerc
> ellps: international
> a: 6378388.0000000000
> es: 0.0067226700
> f: 297.0000000000
> lat_0: 0.0000000000
> lon_0: 9.0
> k_0: 0.9996000000
> x_0: 1500000.0000000000
>
> Hope this helps,
> Markus

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