RTCM transformation using Fieldgenius ISSUE

1

Hello

As I read in this post-
RTCM transformation
RV does not support RTCM transformation for now.

As I mostly use Fieldgenius and connect to the NTRIP network using FG also, I wanted to use RTCM transformation sent from the provider. This way I’m connecting to the NTRIP network through my controller internet using FG.

The transformation from WGS84 to official datum in my country (Serbia, MGI Balkans zone 7, Gauss-Kruger projection ™, central meridian 21, orthometric heights) should be done in 3 steps:

  • 7 parameter datum transformation
  • horizontal GRID shift
  • vertical GRID shift

I’m connecting to the NTRIP network using these settings:

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1632×502 27.7 KB

and the following RTCM transformation is provided:

3
3632×502 26.9 KB

The problem is that FG is applying:

  • Target system and 7 parameter transformation
    (as proof of this, it changed my Easting and Northing from previously set UTM 34N to values of GK7 )
    4
    41366×728 89.2 KB

and not applying:

  • horizontal GRID shift and
  • vertical GRID shift (heights are still on ellipsoid WGS84, and not orthometric, datum TRST [should be around 43 m bellow WGS84])

In the picture above (Link information) I can see that those horizontal and vertical GRID shifts are available (but definitely not applied)

I have tried everything:

  • to set UTM as a coordinate system before connecting and applying RTCM transformation
  • to set MGI Balkans (similar to emitted CS) and vertical system WGS84 or orthometric BalkansEGM08…

And still, no horizontal and vertical GRID shift corrections are being applied.

Is there anyone that can help me with my problem?

2

Is the NTRIP from your provider not already in a local system ? They usually are!

3

No, there are 2 providers, and the base station’s coordinates are WGS84.

Officially, we have to use “PAID :face_with_symbols_over_mouth:” online service called GRIDER and transform measured points from lat long elips.h (or UTM-34N E,N,h) to State coord. sys GK7 with orthometric heights.
We do this by uploading .txt files with point-ID lat long h and then downloading the transformed .txt file. And this is a pain in the …

One of the providers (Oficial Leica distributor in Serbia) additionally offers real-time RTCM transformation to State coordinate system, by connecting to Mountpoints with _CS suffix in mount point name. (This can not be used officially if you are submitting your survey to the cadastral office, but we can use it for other works)

My friend has Leica GS08+ and he gets transformed rover position when he connects to any of _CS mount points that are emitting transformation in RTCM message.

4

Can you point me to a place where it says that? That is highly unusual for an RTK/RTN provider.

5

One of the legal documents for provider w/o RTCM transformation.
Base station coordinates are geocentric XYZ WGS84

http://www.geosolutions.co.rs/resenjeGeotaurNet.pdf

6

As I thought, the coordinates are given in ETRS89.

Names of permanent stations, data on installed receivers and antennas at stations and positions of stations “GeotaurNet - powered by GentooARS” (first phase) of the network in the Serbian Spatial Reference System (SRB ETRS89) are given in the following table.

7

yes, my bad :pensive:

But it is almost the same as WGS84

I’m using SRB_ETRS89 /UTM-34N epsg 8686

8

What system are you using in Reachview 3? What does it require for the base ?

9

That one seems to be a slovenian one? :smiley:

10

8682

11

I’m using ETRS89 in FG, also

12

What are you using for vertical?

13

elispoid WGS84, and then I convert it using GRIDER service to get orthometric heights

14

But what is the name of the geoid you are converting to ? It must have a ESPG code as well ?

15

It’s EPSG 8691 for SRB_VRS12.

16

it is quasi geoid SQM2011, no epsg code

They do not want to provide the public horizontal grid shift values and vertical shift

They say that transformation from ETRF2000 to Gauss-Kruger is 2 steps transformation:

  1. Helmert 7 parameters transformarion for whole teritory of Serbia
  2. Grid shift using bi-linear interpolation on coordinate axises (B,L)

Orthometric heights are calculated by interpolating anomalies of SQM201.

17

Because they can earn money on the conversion? :confused:

1 Like
18

There are a few free and paid online services, apps, and CAD add-ons that can perform the same transformation as state-owned money-hungry GRIDER.
But the only official tool is the so-called GRIDER service.

I compared results from other tools to this official one, and mostly residuals are in a range from 0 to 1 cm

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