Hello,
I am carrying out the EMLID Stop and Go PPK workflow.
The GCPs were collected in the coordinate system ETRS89 / UTM Zone 30N using a specified Geoid model.
When putting in the coordinates of the base unit for the ‘Stop and Go’ do I have to use WGS84 coordinates? Or is there a way to use UTM coordinates.
Also, when generating the corrected CSV file of the GCPS, can the coordinates be exported in ETRS89 / UTM Zone 30N? Or is the export only in WGS 84 and then I have to convert them?
Many thanks!
Hi Andrew
The base position in studio has either geographical or Cartesian as inputs. You can put in lat, long and el height in either DMS or decimal degrees.
If you are using the broadcast data from a national network it will be in etrs89. If so you can select “rinex header” as the option for base position as the broadcast files have the precise location written into them.
For transformation back to local 30N UTM you can import the converted stop and go file straight to a flow project with that CRS setup. It will do the transformation for you.
Cheers
Scott
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Hi Andrew!
You don’t always need to have WGS84 coordinates for the base position in Emlid Studio. If you have an ETRS89 / UTM Zone 30N point, you need to convert it to geographic coordinates (lat, long, height), and the processed point will be in the ETRS89 datum.
I will second @scottmitchell63 that you can import the results point to Emlid Flow. Set a project with ETRS89 / UTM Zone 30N and Emlid Flow will transform it for you.
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If I understand correctly then…
When using stop and go with a known pint I am unable to enter the UTM coordinate as a known point. I need to convert the coordinate first into a geographical or cartesian CS. In this case under the X/Y/Z ECEF I should be able to enter the ETRS89 Coordinates. However, how do I indicate in the software the CS I am using? Perhpas all transformations have to be done outside of Emild Studio?
Also how can I distinguish between ellipsoidal and orthmetric Z values for the base unit?
A
Oh, forgot to give thanks de Scott and Merryna!
Hi Andrew.
Yeah you would enter the Cartesian or geographic positions in studio for your base. UTM is not an option. Other software allow this but they will calculate the geographic and Cartesian in the background and run processing based on that.
If all you have is the ETRS89 based UTM position then I would suggest the following:
Start a project in flow with the CRS set as the local UTM zone and ETRS89 derived and apply a vertical model if known and required.
Input the base location in the UTM values as a survey point. This can be done in local UTM coordinates.
You can then toggle between global and local in the app or desktop version.
Either copy from there or export the project out to .CSV
Copy the geographical coordinates from the CSV into studio base base settings to run PPK stop and go on your rover data.
Once you have finished processing the rover data (results in geographical format) you can reverse the process and import the corrected .CSV from stop and go into your flow project and they will be transformed to UTM for you.
There is no way or need to tell studio about the projected grid system you are using. It has no bearing on the processing of the files as none of the data is relative to any grid system. That’s why the input UTM data seems to disappear once you get to output of results. Studio doesn’t have a module to do those transformations.
Scott
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Thanks for clarifying everything Scott!
