[Qgis-user] NTV2 Grid Shits

[Andre Joost]

Am 20.10.2017 um 14:31 schrieb Tyler Veinot:
> Anyone knowledge in using grid shift files (gsb) with QGIS?
> I have a local CRS NAD27 Double Stereographic Imperial that I need to
> transform to NAD83 CSRS 2010 Epoch. I have the CRS properly defined using
> the provincial description

Can you add your custom CRS? Maybe you have +datum=nad27 which uses the 
main nadcon transformation file. use +ellps=clrk66 
+nadgrids=/path/to/your/file

  but QGIS using its Clark 1866 to GRS80
> transformation puts the points a little off from the NTV2 coordinate
> transformation software we have. I have the GSB used (even though it says
> ATS77 the provincial geomatics guys tell me it shits NAD27 and ATS77 into
> CSRS 2010 NAD83). I followed some directions on putting the file in a
> specific folder and restarted QGIS set the settings to always ask for grid
> shift file for transformations yet I do not see the one I put in there in
> my list to pick from.

Can you explain where that setting should be?


> I also tried to install a plugin for NTV2 transformations but cannot
> activate it. When I go to Activate Additional Providers in my Processing
> Toolbox where NTv2 Datum Transformations resides I get the "Specified Path
> does not exist: C:\PROGA~1\QGIS~1.18\bin" error that I have not yet managed
> to resolve. To my understanding has something to do with GRASS plugins and
> past versions of QGIS.

You can workaround that GRASS error by creating that folder, or changing 
the folder entry for GRASS 7 to an existing folder.
But to use your grid in the plugin, you would need some python code 
around it, like the other grids have in 
C:\Users\<username>\.qgis2\python\plugins\ntv2_transformations
Without that processing would not know about your grid.

HTH,
André Joost