Cut and Fill

Folks,
l’ve just received my RS2s. They look fantastic, now I’ve just got to figure my workflow. I’ve been reading through the tutorials and it all looks good, although it will make more sense as I’m working, I hope.
Just a few questions to ensure I don’t fall down the wrong rabbit hole:
I survey two sites monthly for stockpile reporting and cut and fill measurements. I do not have cellular signal at all. I do not have an established survey mark to use.
I realise I do not need absolute accuracy for either measurement. Occasionally I will be required to find the edge of a pit boundary (not legal boundary markers) so I will need absolute for these.

My thoughts:
find a permanent structure (fence pole, top of a stationary shipping container) and mount a bracket to take the extension pole of the RS2 base station so that I can put it in the exact location month-on-month.
Use Precise-Point-Positioning to get an exact fix on where the base station is (about 5hrs of logging).
Upload the log to AUSPOS* and get my exact position. Use this position on setting up my base everytime and I will have highly repeatable, absolute point for my cut and fill and any internal (non-legally binding) marking out.
Thoughts?
When I have this sorted, I will post my workflow for the next generation.
Joe

*what is the usual turnaround time for AUSPOS?

Hi Joe,

Well done! I have almost nothing to add, some short comments only.

5 hours for AUSPOS should work fine. However, for the best accuracy, you need to wait around 2 weeks before uploading the logs.

Also, the fence pole isn’t as permanent as it looks. If it’s jammed in the ground, it may be shifted after the heavy rain, for instance. The shift is probably only a few centimeters, but it may cost significant accuracy errors. The option with a stationary shipping container looks more reliable.

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Thank you for the reply.
5 hours of data collection in field, the battery wouldn’t last 2 weeks?

In this case, 5 hours of field collection and it ends. After two weeks, send to AUSPOS for use of final ephemeris for more accurate positioning.

ok, now I’m confused.
Why would I wait to weeks to send the information?
Just to be clear:
Day 1: Record 5hrs
Day 14: Send the recorded information to AUSPOS
Why would you wait 14days? Is there a tutorial on this?

Ok, I’ve read the PPP document on the website (https://docs.emlid.com/reachrs/tutorials/post-processing-workflow/ppp-introduction/).
Its quite outdated and doesn’t explain a few dialog options.
Why would you only use GLONASS and not all including GALILEO etc?
My logging interval is 1sec?
I assume I don’t need a measured height?
The tutorial says select RINEX 2.xx but there is now RINEX 3.03, should we be selecting the newest?

This is how all PPP services work. In a few words, you can obtain precise coordinates with one receiver and PPP service because PPP uses data from the global network of ground tracking stations. With the data from these stations, PPP services model GNSS system errors, but it takes around 2 weeks to make it as accurate as possible.

Here’s a note in AUSPOS docs about it as well.

In our docs, we describe the workflow with NRCAN. It’s another PPP service, which requirements differ from AUSPOS ones.

AUSPOS supports both RINEX 3.03 and RINEX 2.xx. You can record all GNSS systems, but AUSPOS will use only GPS data for calculations. Logging interval doesn’t matter, but 1 sec should be enough. However, you still need to know the tripod height to obtain the coordinates of the point on the ground.

Edit. Added a comment about pole height

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Directly quoting the documentation page about the expected accuracy according to the time of raw data collection:

Depending on the accuracy level and time that is required to get the solution, NRCAN CSRS-PPP service can calculate the data in the following modes:

  • FINAL: the accuracy is about 2 cm (0.8 inches), available 13 -15 days after the end of the week
  • RAPID: the accuracy is about 5 cm (2 inches), available the next day
  • ULTRA RAPID: the accuracy is about 15 cm (6 inches), available every 90 minutes

In other words: You can process your data on the same day, after 90 minutes from the end of collection, on the following day or after 15 days. It will depend on the accuracy required for your project. Note that the accuracy of the final ephemeris (~15 days) to the fast ephemeris (next day) is not so different.

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Just put down a solid marker (80D Nail or Wood Hub), let it average for 30 minutes and record the coordinate so that you can manually enter it on subsequent trips. Even if you PPP you are unlikely to match the site coordinates unless you do PPP and every Surveyor and Engineer involved in the project did the same. This is a common scenario in construction and requires CAD skills to align everything to the cm level.

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Chascoadmin I just received my pair of Rs2’s. I will primarily be using them for GCP’s and quick elevation checks on a construction site and maybe layout a patio or small drive. I saw that you mentioned cad skills to align everything. I am curious about your workflow, Autocad? Any videos and or knowledge about your workflow I would love!

Hey Jeff, welcome! What we run into on construction is non-standard data. Ideally the Surveyor would have used the most current datums and the Engineer would design directly off their CAD. Also it would be nice if the survey had happened within the last year to verify that all the horizontal monuments are where the plat said they were and that the CAD would match that as well. They are getting better about this but we still receive 30-40% of the DWG’s that are either not on State Plane coordinates, are using a non-standard EPSG code or have a scale factor configured. I understand the scale factor but it makes it really tough to integrate other data because everything has to be shifted to match that base CAD file.

Any or all of these issues cause us to do what is called a localization. Basically we would locate all of the available monuments and the software compares their relationships to each other as a network and gives us the best-fit scenario.

In our drone program we get corrections to the RS2 via NTRIP so we are always in agreeance with one of the major datums and get live State Plane coordinates as we go. Because all of the problems above we already have discrepancies between the site’s localized coordinates and our network SPC’s. Then there are always discrepancies in vertical when comparing our data with vertical benchmarks that have been level-looped in. At the end of the day we have two choices. Either do our own localization or align the network data with the localized positions in CAD. We prefer to do it in CAD because it keeps all of our drone data on the same coordinates as geodetic sources like GIS and even Google Earth Pro. The alignment in CAD is really easy because there is a one time process of creating a file with the movement that is XREF’d into the CAD we are working on so we can bring up the last set of drone data which are always the orthomosaic and the DTM surface built from the point cloud. We can draw the triangles but if a project gets too large we can just do the contours. With this data we can see the points from survey and the visible locations of the GCP’s to make the final adjustment which is basically localizing after the fact.

I think I might already have a video but can make one on the next map we work on. I only have about 5 of them in front of me, lol. The blessing and curse of having a new pilot flying.

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