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New Zealand | Hi all.
I have read some of the posts about the datum update you are expected to get in North America in 2026. And I have read some of the concerns about lines and boundaries moving.
As a former farmer and tech nerd I have spent weeks over the years mapping fences and creating boundaries and guidance lines to suit, I can understand the frustrations thinking about having to redo all that work, because of the datum change.
I am now a surveyor student, and I am in New Zealand, so I only know some general information about your situation. But I do have a lot of experience with GNSS, RTK and Trimble ag displays. I am now a surveyor student.
This post is mainly to gauge if there is any interest for a service for adjusting existing field boundaries and lines to the new datum. Or to shift lines in general.
I am writing this post and doing this to help, because I think it is an enormous waste of time if people are spending weeks remapping a farm if the problem could be fixed with a few hours in the field and a few hours in the office, depending on the specific situation.
If there is interest, I will write more information on how to get the necessary information to make an adjustment possible.
John Deere Greenstar users, sorry, but unless someone tells me how I can export guidance lines to a file, edit them outside JD Ops Center and then reupload them to a display, I can not help with adjusting lines. I should be able to adjust boundaries from Ops Center and reupload them, but I am not sure if that is helpful. But it sounds like the JD delivered correction signals are not affected anyway.
It sounds like it is mainly the state-run CORS networks that will be affected. It depends on how the operator has set up the base station, and what they are going to do once the datum change happens.
Very simplified, this is what will happen and what must be done to adjust;
If you have a field that is mapped using RTK from a CORS base and the CORS operator updates the position of their base, say 1 foot North, then all coordinates associated with that one field must be updated to a value 1 foot further North, to make the lines and boundaries appear where they are meant to be.
That means all A points and B points, all boundary corners, and all the vertices in curves. It is a lot of points, and practically impossible to do manually with the conversion tool on the NGS website, as it appears to be a single coordinate converter, not suitable for a full dataset (correct me if I am wrong).
The key takeaway is, that within a local area, everything will move the same distance in the same direction.
Think of it as putting a transparent paper on top of your farm map. Draw the fence lines on the transparent paper and then slide the transparent paper a little up or down on your map.
This is important because if this distance and direction is known, it may be possible (depending on your system) to move all lines, boundaries and other marked features in one process.
I have done this successfully with Trimble files exported as shape files (the older AgGPS format that the FMX uses). Other systems should be possible too, it depends on how lines can be imported, exported and edited.
I did it using GIS tools. I was able to load around 60 fields with boundaries, features and guidance lines and shift them all at once with two mouse clicks. A bit easier and faster than spending weeks remapping all the fields.
What I needed was the export of all the fields, and two calibration points (like a fence post, but with one coordinate measured with the old datum and a second coordinate with the new datum)
Please feel free to ask any questions, and to correct me if you think something I wrote above is incorrect.
I am mainly writing this post to help, because I think it is an enormous waste of time if someone is spending two reeks remapping a farm if the problem could be fixed with a few hours in the field and a few hours in the office, depending on the specific situation.
Nikolaj Nielsen
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NAD83 and shifting guidance lines and boundaries
