Ntrip service local coordinates

Hello!

I’m quite new to this so please bear with me. :slight_smile:

I have an RS2 as a base and recently subscribed to a local NTRIP service where I get the corrections from.
The customer I have, would like to use the local coordinates in their CAD software, so to receive the corrections in this local coordinate system, I should use these parameters additionally:
dX=-577.326
dY=-90.129
dZ=-463.919
rX=5.137
rY=1.474
rZ=5.297
ds=-2.423

Unfortunately I don’t see this option in the emlid mobile phone app.

However, the NTRIP provider mentioned that if I would use their RTCM 3.1 data streams with specific mount points, all the transformations would be sent over the data stream.

So I was thinking, the second option is better ? I set up the NTRIP provider with that mount point and start collecting the GCP’s in the project’s local coordinate system, right?

EDIT: The job is to do an aerial survey with an RTK drone whereas the RS2 acts as a base
EDIT2: I’ve figured out that you need to use emlid caster for both base and rover and set the base to output only (not using the NTRIP input) . This brings me one step closer but the question remains about the local coordinate system…

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The NTRIP provider should tell you the co-ord system they are providing correctiond for, check there page.
ReachView3 has a number of predefined cord systems that cn be downoaded , in ReachView 3 start a new project in survey section, fill out the top 3 baes as required, then the fourth box down “Coordinate Syatem” open it and find the system you want to use. Smae for hight datum and away you go.
ReachView3 is fairly basic so points only, FieldGenius for Android is a full features collecter, it unfortunaatly costs.
Hope that helps

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The NTRIP provider can provide corrections in my local coordinate systems, for that I’d need to add those parameters above but I didn’t see any options for that?
Alternatively they can provide me a data stream in RTCM 3.1 where all the transformation data is sent with the data stream…

The predefined coordinate systems you have mentioned they are indeed present and could be used for my purposes. On the bottom of the page however , there is a tip that I should make sure that the base or reference system is in ETRS89 therefore I’m a bit confused.

The RMTCM 3.1 is a protocal that is used, most bases us version 3.2 they both work.
You set the base login details in the Profile section “My NTRIP profiles.” Tip use the EMLID cloud backup usre the same username and passwd as here.
Keep in mind the ReachView 3 phone/tablet and the GPS have to be on the same wiFi network.
The NTRIP provider URL can be a plain language URL (somewhere.com) or the IP address.

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Hi @daniel.dobosi,

Sorry for the delayed response!

I have some questions and some answers for you. Hope that both of them will help us make things clearer :slight_smile:

In what datum are the coordinates of your NTRIP Service’s base? What is the local coordinate system your customer wants to use? As @johnandrewartha49 mentioned, ReachView 3 supports many of them. So probably, they can just pick up the necessary one while creating a project and keep working with it.

In case there is no coordinate system they need in the list of available, they can create a custom one. This video guide can help with that. While creating it, they’ll be able to set the transformation parameters as well.

I see that your NTRIP Service can transmit the parameters of the coordinate system directly in the RTCM3 message. However, at the moment, Reach RS2 can’t read such info from it. So setting the parameters of the CS in the project is the only option for now. But I’ll note your request for this feature and pass it to the team.

And one more question from me. You want to use Reach RS2 as a local base for collecting GCPs in RTK and for an RTK drone, right? Just want to understand your setup a bit better.

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Hello Julia,

let me copy the machine translated FAQ of the NTRIP provider’s mout points here :slight_smile:

  1. GPS /GLONASS/GALILEO/BDS - 4G:

RTK-32-4G: Pure RTK correction data
RTK-32-4G-TR: RTK correction data with included raster residuals
RTK-32-4G-TR-M34, RTK-32-4G-TR-M31, RTK-32-4G-TR-M28: RTK correction data + RTCM3 transformer measurements
RTK-32-4G-ETRF: RTK correction data + RTCM3 transformer messages

  1. GPS /GLONASS - 2G:

RTK-3: Pure RTK correction data
RTK-3-TR: RTK correction data with included raster residuals
RTK-3-TR-M34, RTK-3-TR-M31, RTK-3-TR-M28: RTK correction data + RTCM3 transformer messages
RTK-3-ETRF: RTK correction data + RTCM3 transformer messages
RTK-2.3: Pure RTK correction data
RTK-2.3-TR: RTK correction data with included raster residuals
DGPS: GPS/GLONASS code correction data
DGPS-TR: GPS/GLONASS code correction data with included raster residuals

The customer is working in this system: Austria | Emlid Docs MGI (Ferro) / Austria East Zone

Well, I would use an RTK drone that is correct but I would also like to control the measurements by placing one or more GCP and measuring those with the RS2 before the flight.

I was under the impression that I could receive the corrections in the local coordinate system and transmit them directly to the drone so when I create the project, it will be in the local system…

So I guess I’ll just have to use the NTRIP provider for corrections transmitted directly to the drone and measure the GCP’s by hand in the customer’s coordinate system, right?

Hi @daniel.dobosi,

Based on the names of some Mount points of your NTRIP Service, I assume they are in ETRS89. But it’s better to know for sure. What is the name of this NTRIP Service?

If the base datum is ETRS89, to work with MGI (Ferro) / Austria East Zone, you’ll simply need to choose it while creating a project. And after that, you can easily get local coordinates of GCPs without entering any additional transformation parameters.

Does your drone work with projected coordinates? Can it get the data from RTCM3 messages about the CS parameters and apply it? I just saw ones working with geographic coordinates only.

that’s good to know, I’m going to test this the day after tomorrow!
The provider is eposa.at

I’m not sure, It’s an Autel Evo II Pro RTK - I’m guessing not?
Appreciate the help, Julia.

I’ll search for some info about their datum and share my findings with you. And it would be cool to know the results of your tests! :slight_smile:

I have never worked with Autel drones, so I can’t be sure. But I’ve checked the standard of the EXIF file that contains photos’ metadata. It requires geographic coordinates: latitude, longitude, and ellipsoidal height. And I think that for navigation, the RTK drone uses geographical coordinates as well.

So I think the common workflow is to get geographical coordinates on your drone. Then upload all the data to the photogrammetric software such as Agisoft Metashape. And there, you’ll be able to apply projection and get local coordinates for your project.

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Hi @daniel.dobosi,

I’ve searched for the info about the reference stations’ datum on the EPOSA website. As I see, in Terms of Use and Pricing for EPOSA services [357kB] on page 2, EPOSA base stations are in ITRF2014 and ETRF89. ETRF89 is the realization of ETRS89, so it should suit you.

Can’t be sure how to configure getting the data exactly in ETRS89 from this NTRIP Service. But I think EPOSA support can shed light on it.

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