Here + RTK GPS PH2.1 alt accuracy issues

Leon Dwyer [6:47 PM]
Hi, Guys - I’m here to pick your collective GPS / Geo coordinate brains.
I’m having issues with the Here + RTK GPS alt accuracy. I initially thought it was Mission Planner tagging images with Baro Alt but that seems not to be the case.

So far my X and Y positioning is quite good and pretty much what I would expect for recording a log record via a trigger command rather than the poll. The locations are around half a meter in ‘x’ and 2 meters in the ‘y’ away from their true location.

However, the height is way off. I have data from 2 flights - flight One which is MGA 55 with VRS (NTRIP) corrections and data from flight two which is MGA 54 with base-station corrections. –
Flight One’s images are recording the GPS alt at 13.781905m higher than their actual height based on Ground Control corrections.
And flight two is 13.358103 higher than the Ground Control.

Both flights did not have their N value added during processing - both locations have an N value of 4.5 ish

So 8.7 meters is not accounted for in both instances

I’m hoping I’m missing something obvious like needing to set the input coordinate system in Pix4D to something else than the standard WGS?

Anyone got any clues - if you want my logs and images - you got em.

I would suggest checking ellipsoid vs. geodetic height. In RTKLIB you can select both for post processing, so it might be the case with Here RTK.