Reference System available in Settings but not in Convert

[dpitman]

My local NTRIP service uses IGS08 (EPSG:6934).  I have monument coordinates in NAD83(2011). So I need to transform the positions collected by gnss to NAD83(2011)

In MS, in the Reference Pane  Settings, I can select either of those systems.  But in the Convert dialog, the ISG08 system is not available?

[Alexey Pasumansky]

Hello Dave,

Coordinate transformation in Metashape is possible to the systems based on the same datum or via WGS84 system, providing that ToWGS84 transformation parameters are available both for source and target coordinate systems.

It seems that according to the ESPG registry data there is no ToWGS84  transformation available for IGS08 (EPSG:6934), therefore if your source data is it this system, you need to input the transformation parameters via Datum Transformation Parameters dialog accessible from the Reference pane settings dialog. After that you will be able to select other target coordinate systems in the Convert Reference dialog.

[dpitman]

Hi Alexey,

Thanks for the reply. Any idea where I could find an online resource to determine those offsets?

Best regards,
Dave

[Paulo]

Hello David,

basically IGS08 datum is equivalent to WGS84 so all parameters should be set to 0. But you should use the latest toWGS84 parameters for NAD83(2011) to get a good transformation...

Official parameters published are:

NAD83(2011) Transformation parameters                     
   TOWGS84 (IGS08)                  
Epoch   TX(m)     TY(m)        TZ(m)           RX(as)                RY(as)                RZ(as)                 DS(ppm)
2010   -1.0037   1.91111   0.54397   0.02678138   -0.00042027   0.01093206   -0.00038891

[dpitman]

Paul, thank you for the help !