[GRASSLIST:8227] Gauss-Boaga location and wgs84 proj parameter

[Luca]

Im going to create a Gauss-Boaga location where to load some 
georeferenced maps. This is what I have done:

*1.*

Please specify the coordinate system for location <tempo>
A   x,y
B   Latitude-Longitude
C   UTM
D   Other Projection
RETURN to cancel

 > D -> I'll create the location with the Other Projection procedure.
*
2.*

Please specify projection name
Enter 'list' for the list of available projections
Hit RETURN to cancel request
 >tmerc  -> i think is the right projection

*3.*

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
 >rome40 -> it is right, isn't?

*4. ------here is the problem----------*

Number  Details
---
1       Used in Italy (Peninsular Part)
        (PROJ.4 Params towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68)
        Accuracy 3-4m
---
2       Used in Italy (Sardinia)
        (PROJ.4 Params towgs84=-168.6,-34.0,38.6,-0.374,-0.679,-1.379,-9.48)
        Accuracy 3-4m
---
3       Used in Italy (Sicily)
        (PROJ.4 Params towgs84=-50.2,-50.4,84.8,-0.690,-2.012,0.459,-28.08)
        Accuracy 3-4m
---
4       Used in Default rome40 region
        (PROJ.4 Params towgs84=-225.000,-65.000,9.000)
        Default 3-Parameter Transformation
---

What is the right number? i would think that is the /*1st*/ (couse im in 
the north of Italy) or the /*4th*/
How can i know which towgs84 parameter have i to use?
and.. if the right parameter is the first, why is there the 4th 
parameter, that is so strange?


sorry for my english.... thanks

Luca P.


 
 
 --
 Email.it, the professional e-mail, gratis per te: http://www.email.it/f
 
 Sponsor:
 Logos Finanziaria SPA. Società di credito ad erogazione diretta. Fino a 30.000 euro in 24 ore! Clicca e scopri come
* 
 Clicca qui: http://adv.email.it/cgi-bin/foclick.cgi?mid=2909&d=9-9
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/grass-user/attachments/20050909/826fd0e1/attachment.html