What would give the best accuracy on a surveyed site

We have an RTK VRS network where I live, and it works great! I am doing some settlement monitoring. With that said, we had a licensed survey company set multiple control points on the site.
What would give me more consistent and accurate results from GPS

  • Using the RTK VRS network with solid internet and an RS2+

  • Setting a base over the known control entering the data and using a second RS2+ as a rover
    to collect data.


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Does the data have to be on their coordinate basis? Have you staked any of their points from the RTK network? If they match within tolerance then just go get it done. If not then import their points into Flow and use the RTK network to localize to their points. If you don’t have localization and the progression has to be on their coordinate basis then you will need a base and rover. If the progression is fine relative to itself then just use the network. Make sure to compare elevations. Data can always be transformed back to their basis if it ever comes up.


Setting base on provided control points.

Why not use what’s provided ? The “control points” were established for the project.

If you use the RTN, you are introducing additional error in your project . Your measurements from the RTN may not match the control points .


I did stake some of their points with RTK, N, E was spot on, but the elevation was off on one point out of three by a 10th.



To obtain precise elevations with GNSS, several days of observation will be required.

Besides, you didn’t mention how the control points were established.

Whoever provided the control may have established elevations by differential leveling. GNSS derived elevations very rarely match differential leveling techniques unless precise procedures are used. Leveling is more precise than GNSS determined elevations


If the other two were good and running a level shows that the 3rd point is indeed out of relativity then I would bet you are good to go. Just use your rover on the network if that is going to meet the accuracy requirement for the progression analysis.

One thing I would encourage is for you to establish a point yourself off the network on either end of the subject area and have the Surveyor shoot it and concur… or not.


They used GNSS for control


Good Advise, Thank you

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I also thought about getting an auto level for this project.

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Maybe just my opinion but very darn person that is doing any kind of mapping or layout should own an auto-level… and know how to use it. When we were running the RS+ L1-only I use to level through all my GCP’s… Now were have better receivers and dependable RTK drones but I still level my initial checkshots when I don’t have Surveyed data.


We use Leica Spinters (250m) model. They are very reasonably priced, and use the Sprinter rods included. They are very precise using the barcode rod staffs, 1.0 mm per 1 km double run.

We’ve checked leveling with the Sprinter against our Trimble S6 robot using trigonometric methods for elevations and there’s basically not much difference. The Sprinter is usually used for industrial layouts of machinery in precise leveling and documentation . They are also fairly accurate determining distances in short measurements (<100m). If any old school surveyors remember three wire leveling you’ll understand.

I agree with Michael, every construction firm and surveyor should have one.

Leica_Sprinter_Series_-_Brochure.pdf (1.7 MB)


That level is AWESOME!

We’ve been using the Leica NA324 and have never looked back from the Topcon. If you aren’t an everyday user I would also recommend the Spectra AL28A. Good for spot checking but I wouldn’t constantly run it on long level loops.


An auto-level is good to have, but a total station is even nicer (even if it is an older model). Vertically, you can achieve good results using trig levelling. The NGS has a number of old and newer guides on the matter.

The attached states expected precisions per distance and total station.
Precise_Trig_Leveling_PPT_Rev010731.pdf (143.6 KB)

Current guide:

Jesse Kozlowski and Charlie Glover put out a lot of good literature on the matter.

The total station also has the advantage of checking the horizontal and the vertical at the same time. Granted, it costs a fair bit more than an auto-level.


So I should have said this from the beginning, we have 44 points we have to do settlement monitoring a day, over a quarter mile spread with buildings in between. while we dewater 1.5 million gallons of underground water a day. for 2 years…
I’m looking for a fast but accurate enough way to get this done.
Wish I could use a drone…

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ATV and GNSS as long as data within acceptable tolerance.


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Seems LiDAR would be an option… overkill for 44 points though… expensive $$$$

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The company would never buy this, and the county (Owners) would never allow this, they don’t trust or understand new technology. This is the first time they have seen photogrammetry because of me. I got some very cool shit going on with drone maps and shapefiles, points, and Land XMLs
I will show more on that later

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Hi @mcwllc702,

I agree with Michael and Bryan. Both of these options - using the RTK VRS network or setting up a base station over the known control point - can provide high absolute accuracy.

But here are the things to consider:

  1. If the project relies heavily on the provided control points, you may want to consider setting up a base station over these known control points. This approach ensures that your measurements align precisely with the provided data and minimizes potential errors.

  2. If it doesn’t, using RTK VRS is a more convenient option. Moreover, utilizing the second receiver as a rover speeds up your surveying process.


Is localization only in Survey+? That gives you the best of both worlds…

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