[Qgis-user] Extract lat/long coordinate from a custom projected layer

[Giovanni Manghi]

Hi Pietro,


> I have a list of points in monte mario Italy zone 2 - 3004 that I want to
> reproject to Lat/long WGS84 with conversion between these two crs based on a
> NTV2 grid file.
> 
> So, I load a xy temporary layer in a 3004 crs project and I save it as a shp
> (3004).
> 
> Then I change the crs to 4326 and I use the transformation manager
> (transformation tool) pluigin to adjust the on the fly reprojection from
> 3004 to 4326 based on the NTV2 grid file.


that's not how transformation tool (TT) works.

In TT create a transformation selecting the two CRSs (call them "A and
B" or "start and arrive", as you want) and the method (towgs84
parameters ot ntv2 grids) and save it.

Then close TT and add normally your layers. Depending on your project
CRS and the CRS of the layers you are adding, if the two CRSs will "fit"
one on the transformations you defined in TT, then a dialog will pop up
asking if you want to apply one of those transformation to the layer you
are adding.


cheers

-- Giovanni --