[Qgis-developer] Datum Transformation - parameters for mainland Portugal

[Andre Joost]

Am 19.06.2014 20:37, schrieb Giovanni Manghi:

 >
 > the proposed transformations are OK and widely accepted and used in
 > Portugal. On the other hand it seems there is little interest from the
 > official authorities to contribute to the upstream projects/libraries,
 > so to help average Jane/Joe having those in QGIS will be very useful.

I gave a little overview on available Portuguese datum shifts in the 
EPSG database here:

<http://gis.stackexchange.com/questions/45456/how-can-i-see-the-coordinate-transformation-parameters-in-qgis>

Unfortunately, the transformation with the least accuracy is implemented 
in GDAL/PROJ. It would not be much work to select one of the others as 
default. I could open a ticket for that, but I don't have any official 
reference data to proove the accuracy.

The values supplied by Pedro are similar, but they should go the 
official way into the EPSG database. This does not have to be done by 
local authorities. The EPSG registry website remarks:
"Change requests are accepted from any interested party. They should be 
made by electronic submission of the change request and comment form on 
the make change request."

I suggest to raise the topic on the GDAL or PROJ mailing list before 
making a change request.

But I would not encourage to delete any EPSG code and invent new ones 
inside QGIS as Pedro suggested.

Greetings,
André Joost