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

[Pedro Venâncio]

Hi Andre and Marco,

These parameters are outdated. The current and official parameters for Molodensky and Bursa-Wolf transformations are those which are currently in the Directorate-General of the Territory website [0], and which are those that I proposed. 

In addition, the Datum Transformation, at this moment, does not work for Lisbon Datum, because the code of the geographical system used by EPSG:20790 is not EPSG:4207 [1], but EPSG:4803 [2], as you can see here [3].

No doubt that the ideal would be to have these transformations in proj and gdal, but that should be much more complicated, because these projects should get the information from EPSG database, and almost sure that this update, even if it can be requested by us (portuguese QGIS user group), it will take time.

However, doing this update in Datum Transformation, would enable the use of NTv2 grids, and Molodensky and Bursa-Wolf transformations with the latest parameters, very easily (especially if we could place the grids directly in QGIS). I doubt there is another GIS software with this capability!

Regarding the possible bug that I spoke in the original post, what do you think?

Thank you very much!

Best regards,
Pedro


[0] http://www.dgterritorio.pt/cartografia_e_geodesia/geodesia/transformacao_de_coordenadas/ 
[1] http://epsg.io/4207 
[2] http://epsg.io/4803 
[3] http://epsg.io/20790