Elevation difference Question

[dmterblanche (David T)]

Hi

Reach working well, i have 2 RS+ units ( Base and Rover ), I have not issue staking out points so far. x and y value we very happy with. Howerever I have a question:

A land surveyor got a elevation on a point as 1427.13m M.S.L on a bridge nearby us.
I went to a old suveroy beacon nearby, whose cordinates I have. I got <30cm accuracy on Zaxis on that existing value.Which is acceptable.
I then to the bridge which they did a point on and I get 1424.88m M.S.L To reduce any discrepancy, I placed both base and rover directly on the curb about 1m apart. so there was no difference in height between them. I got a fix solution. So what could the difference be then?

https://drive.google.com/open?id=1gZ-xmepFXMKEfM7Ebqdd2iIW5megFRVO

[timd1971]

First off, you DO NOT want to just place them directly on the ground like that in your photo!

Put them both on survey rover poles with a set height i.e. 2m rover pole is convenient. And enter the total height of pole plus thread adapter plus height to antenna (printed on bottom of RS+).

There are many posts abouts rover poles, tripods, rover pole tripods, bipods etc.

Recent post:

Tripods

hi all thus is my first post, what options do i have if i want to buy a tripod, i cant see any for sale in the store

[dmterblanche (David T)]

Hi ,

Thanks, I did place on survey pole and tipod on previous try. I just placed on floor for a test, even sub meter accuracy do as test.

[michaelL (Michael Lambert)]

Here we go again with the ellipsoid vs geiod vs survey ground coordinates… 30cm is ok?

Ground Datum Use

Is anyone here actually using their Reach (RS+/M+) for surveying and/or drones to provide data related to the surveyed ground. I feel like an outcast when I bring this up because - it seems that many people are fine with ellipsoid and geoid elevations?

[tatiana.andreeva]

Hi @dmterblanche,

I agree with @michaelL.

In the meantime, you can see only the ellipsoid height in ReachView. You can get orthometric height after post-processing, using RTKLIB. Check our GPS post-processing guide for it.