Hello,

New to drones not to handling drone data but new to processing in DJI Terra. Recently purchased a DJI Matrice 350 RTK and Zenmuse L2 for Lidar surveys and I have since conducted multiple flights. All of the flights I am processing were with RTK and had no drops in RTK. Each flight was setup on a known point (NAD83-UTM coordinates converted to WGS) but an average reading for the height was used (reading from setting up RTCM in the web browser). I am making the corrections to the base point in DJI Terra but the processing stops part way through with an error stating there is an Altitude Error. If i dont make the corrections the scans process no problem.
Is this because the RTB file has the original coordinates and the inputted coordinates differ and Terra doesnt like that? Would an OBS file to overwrite the RTB file fix this issue? Is there another solution to correcting this data because I opted to not log the base during these specific flights (thinking that the base should be logged regardless with having the issues i currently am).

RTB contains the coordinates received by the base station.

It is neither more nor less than an RTCM3 file that Terra converted into RINEX with the coordinates in the header.

If you modify them, depending on the gap that you are going to give them there will be a problem yes.

Why are you modifying these values?


"I am making the corrections to the base point in DJI Terra"
It is the part that i don't understand.

I am modifying these values because even though I inputted the correct base station coordinates setting up RTK through the web browser they are not the correct values when i load the project into DJI Terra.

dbetts4 Posted at 11-26 10:14
I am modifying these values because even though I inputted the correct base station coordinates setting up RTK through the web browser they are not the correct values when i load the project into DJI Terra.

I'm sorry but I don't understand what you're writing.

What are you using? A DRTK2?

Also this may help you :
Alternative to DRTK2 and NTRIP Provider | DJI FORUM
DJI Products EXIF Wrong Altitude / How to solve it | DJI FORUM

I am using a Trimble R12 base station and setting it up through NTRIP Caster. Prior to arriving on site I converted my NAD83 coordinates to WGS and inputted those coordinates into the reference station through the web browser. On DJI Terra side, after uploading my flights the coordinates shown are not the coordinates that I inputted as my reference station. When I input the correct values the processing stops with an altitude error.
I understand the difference between the Geoid, Ellipsoid and Ground. I am not understanding why the reference station cannot be adjusted post flight.

dbetts4 Posted at 11-26 12:16
I am using a Trimble R12 base station and setting it up through NTRIP Caster. Prior to arriving on site I converted my NAD83 coordinates to WGS and inputted those coordinates into the reference station through the web browser. On DJI Terra side, after uploading my flights the coordinates shown are not the coordinates that I inputted as my reference station. When I input the correct values the processing stops with an altitude error.
I understand the difference between the Geoid, Ellipsoid and Ground. I am not understanding why the reference station cannot be adjusted post flight.

If you forward me the OBS file, The RTB and the RTK, i could take a look.

But there may be an issue in your R12 settings because it must broadcast the station coordinates correctly.

https://drive.google.com/file/d/1-jtRxpRVAwMjP1a_NXM0-37D49MlEz_v/view?usp=sharing

I have uploaded the files to this link. I didn't log my base because it was setup on a known point. With what i am deal with currently I see the need to log regardless. However, if itll help the coordinates of the base point i setup on and inputted into NTRIP Caster1 are:

N48° 38' 57.307056",W88° 41' 58.676257",264.141

dbetts4 Posted at 11-27 05:16
https://drive.google.com/file/d/1-jtRxpRVAwMjP1a_NXM0-37D49MlEz_v/view?usp=sharing

I have uploaded the files to this link. I did log my base because it was setup on a known point. WIth what i am deal with currently I see the need to log regardless. However, if itll help the coordinates of the base point i setup on and inputted into NTRIP Caster1 are:

The link is pointing only to the RTK file, i cannot do much only from that file. An OBS or RTB is necessary.

However, the RTK file seems to be without default.
I see a flight that start at 15h24:55 07/11/2024 and finish at 15h37:42 .. UTC !

https://drive.google.com/file/d/1-iN_xEiUNF5qh3tSK1GvyR9LEyWdmFXl/view?usp=sharing

Try this link. I must have no selected the RTB file.

dbetts4 Posted at 11-27 06:26
https://drive.google.com/file/d/1-iN_xEiUNF5qh3tSK1GvyR9LEyWdmFXl/view?usp=sharing

Try this link. I must have no selected the RTB file.

There is one part of the flight which cannot be solved with this RTB file. In your Trimble there should be a RINEX or OBS file.


But obviously the issue comes from the base station position / configuration. Observations are very poor.

This is a consistent OBS file :

Ok so why does that correlate to the altitude error I am getting in DJI Terra when I input the correct base position to process? Also the quality report post flight in the field returned no drops in GPS quality during the flight. Should an OBS file replace the RTB file regardless of a RTK or PPK flight?

dbetts4 Posted at 11-27 06:51
Ok so why does that correlate to the altitude error I am getting in DJI Terra when I input the correct base position to process? Also the quality report post flight in the field returned no drops in GPS quality during the flight. Should an OBS file replace the RTB file regardless of a RTK or PPK flight?

"why does that correlate to the altitude error I am getting in DJI Terra when I input the correct base position to process?"
In my opinion its a base station configuration issue. I see it at 261.374m (WGS84 ellipsoid)


"the quality report post flight in the field returned no drops in GPS quality during the flight"
I will not give any credit to this kind of quality report. Because even if you receive the signal from a single satellite during the entire flight, it remains 100% good signals. And yet it is not enough. So there are clearly gaps in the development of this report.


"Should an OBS file replace the RTB file regardless of a RTK or PPK flight?"
You have two option, two base station from different network.
On CANNET there is a station located in Thunder bay (CTH2)
On TOPNET there is also one station in Thunder bay (THDR) and one in Nipigon (TNPN)
They are quite far, but you can give a try.




Keep in mind that it is not real RTK. The LiDAR is storing the correction received during the flight in the RTB file. Which is finaly just an OBS file.
Then it Post Process it in Terra.So while being connected to a base station, sending the correction in real time or adding the OBS file during process, must give the same result (from the same base station).
I would say its up to you. If you can legaly fly far enough then there may be connection loose and gap in RTB file data. So in this case it is better to add the file in post process.

Ok thanks for the information and appreciate the time.

LV_Forestry Posted at 11-27 06:33
There is one part of the flight which cannot be solved with this RTB file. In your Trimble there should be a RINEX or OBS file.

[view_image]

How did you generate this graph?

dbetts4 Posted at 12-11 08:11
How did you generate this graph?

https://docs.emlid.com/emlid-studio/kinematic-processing-workflow/

LV_Forestry Posted at 12-11 08:21
https://docs.emlid.com/emlid-studio/kinematic-processing-workflow/

How did you manage to display the Satellite quality with only my RTK and RTB files? Changing the file extension to .obs and dragging over just displays a blank window.

dbetts4 Posted at 12-11 09:12
How did you manage to display the Satellite quality with only my RTK and RTB files? Changing the file extension to .obs and dragging over just displays a blank window.

Change file extension to .RTCM3, then run convert to Rinex.

LV_Forestry Posted at 12-11 09:21
Change file extension to .RTCM3, then run convert to Rinex.

Perfect, thank you!

dbetts4 Posted at 12-11 09:23
Perfect, thank you!

I just realized why you have such a poor FIX.

Your base station is GPS/GLO.

To do it properly it is recommended to have Galileo and/or Beidou in addition.
Same comment as in this thread : Lost data on L1 Processing | DJI FORUM

LV_Forestry Posted at 12-11 13:00
I just realized why you have such a poor FIX.

Your base station is GPS/GLO.

That makes sense. I was under the impression that the Matrice 350 only accepted RTCM broadcast format, which only connects to GPS and GLO satellites, when setting up the drone for a RTK enabled flight. Unless I wasn't configuring it properly, whenever I enabled CMR within NTRIP CASTER1 the Matrice wouldn't connect to RTK.