[gdal-dev] gdaltransform results differs from qgis

[Markus Neteler]

On Mon, Sep 15, 2008 at 11:02 AM, Antonio Parrotta
<antonioparrotta at gmail.com> wrote:
> Hi All,
>
> I'm facing in  strange result using gdaltransform. What I'm doing is to try
> to trasform coordinates from WGS84 to Gauss-Boaga:
>
> gdaltransform.exe -s_srs "WGS84" -t_srs "+proj=tmerc +ellps=intl +lat_0=0
> +lon_0=9 +k=0.9996 +x_0=1500000 +y_0=0 +units=m
> +towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68"
> entering lon and lat
>>7,69746 45,106977<enter>
> it gives
> 1342393.88434212 4984915.97865081 -47.0342488819733
> doing the same transformation with qgis (same parameters), I have
> 1397559,446 4995677,02
> that is quite near to the target expected also checking out in map.
>
> Do we know the reason of this delta? Do I have to set any other correction
> parameter?


Using cs2cs from PROJ4 Rel. 4.6.1, 21 July 2008, I get:

cs2cs -v  +proj=latlong +datum=WGS84 +to +init=epsg:3003
+towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68
# ---- From Coordinate System ----
#Lat/long (Geodetic alias)
#
# +proj=latlong +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
# ---- To Coordinate System ----
#Transverse Mercator
#       Cyl, Sph&Ell
# +init=epsg:3003 +towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68
# +no_defs +proj=tmerc +lat_0=0 +lon_0=9 +k=0.9996 +x_0=1500000 +y_0=0
# +ellps=intl +units=m
#--- following specified but NOT used
# +no_defs
7.69746 45.106977
1397556.77      4995679.28 -46.70

Using gdaltransform on Linux (almost current SVN), I get:
gdaltransform -s_srs "WGS84" -t_srs "+proj=tmerc +ellps=intl +lat_0=0 \
  +lon_0=9 +k=0.9996 +x_0=1500000 +y_0=0 +units=m \
  +towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68"
7.69746 45.106977
1397556.76994996 4995679.27916302 -46.6971342787147

which is the same as the cs2cs output.

How old is your gdaltransform.exe and where does it originate from?

Markus