Vertical datum shows no difference

Using a base/rover setup with RS2 I’m still having problems working out vertical datum. I conducted an experiment just to see if I could get different heights for the same point by setting up one survey project in RV3 using NAD83(PA11) / UTM zone 5N with ellipsoid heights. I set up another survey project in RV3 using NAD83(PA11) / UTM zone 5N + NAVD88(GEOID12B) height. I setup my base station over a point determined by OPUS PPP and placed the rover in another spot not far from the base and made sure the status is “FIX”. I collected one point in the first project using ellipsoid heights and then collected the same point in the second project using NAVD88(GEOID12B)height and the heights are almost exactly the same (788.561 m vs. 788.567 m). According to the NGS/NOAA Computation of GEOID12B Geoid Height website, there should be 20.692 m difference in height. What am I missing?

Wonder if the GEOID12B data in ReachView3 is incomplete for your zone (UTM 5N)???

But what I don’t understand as it states NONE for HYBRID geoid model???

But it shows downloads here???

Odd as below does provide geoid height (positive, above ellipsoid).

Thanks for your comment about 3rd party apps (Field genius). How much does that cost? I work for a farm and it took me almost two years to convince them to even spend money on the Emlid receivers. I can’t imagine what they will say if I tell them we spent this money and now I have to ask them for another $$$$ on software. If I can’t make it work through Emlid I guess I’ll have to spend extra time manually converting all my points from ellipsoidal to orthometric through the NGS websites. Any open source options out there that could save time?

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Yes, you see NGS lists “W0 from USGG2012” for their transformation, but that does not exist in Emlid’s options. I tried using the vertical datum for American Samoa Emlid lists in their documentation as being compatible with NAD83(PA11), but it is not compatible in Hawaii. I got an “out of range” error when I tried it. American Samoa is in a different hemisphere 6 hours flight south from my location.

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Hi @sweet.scott,

There are two values in the CSV file: one is ellipsoidal height, and another is orthometric height.

Am I correct that you’re checking the right height value in the CSV?

Share your logs and CSV file by sending them to support@emlid.com so that I could check your data and determine what went wrong.

Hi @sweet.scott,

Thanks for the email! I’ve checked your data and discussed this case with the team. It looks like we currently don’t apply Geoid at all for Hawaii.

We will add the support of the geoid for Hawaii in our future releases, probably this year.

The current workaround we can recommend is to use an ellipsoidal height and then transform them to the required.

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