Correction of points surveyed with rover with PPP results

Hi,

Let’s say I had a base set for static observation over an unknown point for 4 hours. Then took the logs and processed it with PPP. I now have the position of the base.

During those 4 hours, I used a rover with RTK to the base to survey points. I have a CSV for those.

What is the process in RTK Lib (or other free software if possible, I know about EzSurv) to correct those points in the CSV to the new base?

Thank you

You simply just process the Rover data using the Base data with your PPP’ed base position.

RTKLib will let you do that easily.

In EzSurv, now you mention it, there is also a nifty comparison function, that compares the RTK-positions with the PPK’ed data. That will then show the offsets for each point. Perfect for blunder-detection as well.

You could in any CAD program do the following:

  • Plot the RTK CSV coordinates and the Averaged Base coordinates as points.

  • Plot the PPP’ed coordinate as a point.

  • Select all the RTK points and the Averaged Base point.

  • Move selection with Averaged base point as anchor to the PPP’ed [new] point.

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Hi, might be easy for you, but I would like a tutorial or something.

Thanks

Any idea how to do it in RTKLib?

Not confident with RTKLib…use TBC and Civil3D mostly…issue I have found though is that TBC doesn’t seem to recognize or want to recognize the RS2 antenna or receiver when I import rinex files even after i added the .atx file to the NGS file directory.

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Carlson Survey is a great package for the professional Surveyor as well as the non-professional. Great CAD and COGO routines to use. We’ve been using at least 20 years.

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RTKLIB is great software if you are knowledgeable in the package, my issue is it’s only designed for single baseline processing. I used only shortly when Ublox first designed their beginning chips to export raw data. It was fun to explore, but lacked the capability to compute multi baselines.

When TGO was still functionable, you could PP Ublox rinex files with ease. I’ve had good success with Javad Justin PP software using Ublox rinex files.

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TGO means Trimble Geomatics Office…I thought Trimble still supports that.

Yeah the lack of Multiple Baselines and Network Adjustment is a no for some people.

Someone mentioned UBLOX as being the RTK engine Emlid uses…which do Trimble, Leica, Topcon and the others use?..I’m thinking they are open-source project.

Not sure RTKLib has adjustment functionality…correct me if I’m wrong anyone.

Hi @AeriaPhoto,

If you know the base position that was averaged during RTK, you can calculate the shift between these coordinates and the coordinates you’ve received from PPP. After that, you can add this shift to the points you’ve measured. It can be done in software like Excel.

If you work with ReachView 3, you can check the averaged base coordinates in the output CSV file.

Also, you can use the method that Christian suggested. However, in that case, you’ll get a continuous position log, not the exact points you’ve measured during RTK. If you’d like to know more about that, please let me know. I’ll be glad to share more info.

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Hi,

Just to confirm, the base elevation in the CSV is the ellipsoidal height?

Thanks

Yes, you’re right.

And for processing purposes in a software such as Metashape that I can input accuracy, would I add the RMS in the CSV to the RMS calculated with NRCAN? Since I assume both errors add up?

The resulting stdev in the CSV is the spread of solution at that given point with that given baseline. You can use that directly in Metashape as relative precision in relation to your base.

If you want absolute accuracy you should add receiver hardware accuracy + PPM (in accordance with length of baseline) + the given stdev of the point. I wouldn’t use this for Metashape, only for a report or figuring out if I should shorten the baseline, that sort of stuff.

Hi @AeriaPhoto,

There is no need to add RMS from the PPP report to RMS from CSV. For Metashape, relative accuracy is needed. You’ve added the fixed offset to points coordinates. The accuracy with which you measured them hasn’t changed.

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Jeito mais simples e fácil

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