[GRASS-user] point reprojection: v.proj vs cs2cs results

[ivan marchesini]

Dear Maciej,
thanks a lot...
yes, effectivelly I have forgotten to use the datum transformation
parameters for UTM-ED50...
but today I have also learn, from you, that I can use cs2cs directly
from a projected system to another projected one, without passing from a
latlong system...

many, many thanks...

Ivan



On lun, 2006-07-24 at 12:01 +0200, Maciej Sieczka wrote:
> ivan marchesini napisał(a):
> > Dear Users,
> > 
> > I need to reproject a point (280799|4802457) from location A to location
> > B
> > 
> > these are the PROJ_INFO files:
> > _______________________
> > LOCATION A (UTM ED50)
> > 
> > name: UTM
> > datum: eur50
> > towgs84: -87.000,-98.000,-121.000
> > proj: utm
> > ellps: international
> > a: 6378388.0000000000
> > es: 0.0067226700
> > f: 297.0000000000
> > zone: 33
> > ______________________
> > 
> > and
> > ______________________
> > Location B (Gauss-Boaga EST Rome40)
> > 
> > name: Transverse Mercator
> > datum: rome40
> > 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: 15.0000000000
> > k_0: 0.9996000000
> > x_0: 2520000.0000000000
> > y_0: 0.0000000000
> > __________________
> > 
> > 
> > if I try to use v.proj for the point, from location A to Location B,
> > I obtain this coordinate (into location B):
> > 2300732.60711273|4802279.27423501
> > 
> > --------------------------------------
> > 
> > Instead, if I use cs2cs:
> > 
> > echo "280799 4802457 263" | cs2cs -v +init=epsg:23033 +to +proj=latlong
> > +datum=WGS84 |cs2cs -v +proj=latlong +datum=WGS84 +to +init=epsg:3004
> > +towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68
> 
> Correct cs2cs syntax would be:
> 
> $ echo "280799 4802457 263" | cs2cs +init=epsg:23033
> +towgs84=-87.000,-98.000,-121.000 +to +init=epsg:3004
> +towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68
> 
> which gives:
> 
> 2300732.61      4802279.28 265.39
> 
> OK?
> 
> Maciek
> 
-- 
Ivan Marchesini
Department of Civil and Environmental Engineering
University of Perugia
Via G. Duranti 93/a 
06125
Perugia (Italy)
e-mail: marchesini at unipg.it
        ivan.marchesini at gmail.com
tel: +39(0)755853760
fax: +39(0)755853756
jabber: geoivan73 at jabber.org