I'm helping to ensure that open source software can handle Australia's new datum appropriately, see ICSM's website for details on the GDA2020 project.
Now, QGIS has already got the definitions of GDA2020 included, via GDAL, I understand.
An example GDA2020 coordinate reference system is this:
+proj=utm +zone=55 +south +ellps=GRS80 +units=m +no_defs
And if you look at a GDA94 CRS, it's defined like this:
+proj=utm +zone=55 +south +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs
As you can see, these are very similar.
Now, the two CRSs are defined exactly the same, but, there's a shift in coordinates in GDA94 to GDA2020 of around 1.5 m to the north-east. (There's a grid shift file in NTv2 format that will soon be ready that will enable precise transformations, but that's not what this question is about.)
But, if you convert between GDA94 and GDA2020 now, using QGIS, there's no change in coordinates. It essentially just labels it differently.
My question is this: should Should there be a simple 7 parameter transformation implemented in Proj.4 or other open source tools that is the default transformation (albeit, imperfect) between GDA94 and GDA2020?
Or is it simply the case that the tools will always do no change?
How should this be handled?
(And I just want to note again that transforming using a grid is ideal, and that's handled in a few ways including this QGIS plugin.)
