Phantom 4 Pro RTK and NTRIP

I entered Lat\Long and ortho elevation in meters. Looks like diff between geoid and ellipsoid about 16m

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When I process with PIX4D I can choose “Geoid height above ellipsoid” =0 but I dont know the setting in DD.

I can see why this is confusing. The P4RTK uses the WGS84 Ellipsoid. The GRS80 (NAD83) Ellipsoid for Canada is slightly different. I do not know what the difference is in your area so it is worth researching your location. It could be 0.4m?

I assume the Topcon is using a localization? What vertical datum was used to create that network? It could be a local benchmark level-looped in or generated newly from an NTRIP and converted to orthometric height. Terrain elevations can easily differ from orthometric elevations when calculated from the Ellipsoid and Geoid.

I don’t mean to get to far off into the weeds, but these are some of the GNSS factors that usually contribute to elevation busts.

What I figured out after some research:

Separation between WGS84 and GRS80 is -0.431m in that point.
Thank you MichaeL. You opened my eyes. I still need to verify it but I think that is why.

Cool, I’m glad it was that “easy”. Be sure to let us know how it turns out. I personally don’t have a P4RTK and I don’t know for sure, but it really surprises me that they can’t get the right Ellipsoid based on location or at least give you the option to change it. I guess they figure it will all be done in post processing. Just another little detail they missed.

Even though you can’t fly with DroneDeploy it makes me wonder how it would be dealt with in their system since there is no conversion of vertical datum.

For sure I will keep you updated. I will fly when the temperature will be more comfortable for drone.
I am absolutely agree with you. It just pissed me off when DD not choose correct ellipsoid when you select your local CS or give the option to change it. Appreciate your help. I am waiting the solution from DD tech support for a week now. Still didnt get one.