Do You Ever Talk With GIS Technicians Working Out In The Field?

National files available here (which may or may not be the same as your state files):

https://geodesy.noaa.gov/datasheets/

I was actually just going through my files the other day, deciding which benchmarks to include in a map I'm making.

[edit] Also, to answer the question of whether I ever talk to GIS technicians in the field, the only time that comes to mind was about 4 years ago, when someone from the Forest Inventory and Analysis Program pulled up to my house and asked permission to visit a location on my land. He only wanted to collect data about the trees in s 24-foot diameter circle which was right on the edge of my property, next to my neighbor (and he also had two locations on their land).

I told him he was gonna get a lot of ticks if he walked through the woods over there, he said "I know, I've already had lyme disease once!"

For a large portion of my career I was involved in airborne remote sensing, primarily LIDAR and imagery. Georeferencing airborne data is significantly more complicated because you need to know the precise attitude of a moving aircraft in addition to the precise position of the moving aircraft. The airborne GPS/INS system cost was in the mid six figures and required post processing with a ground base station data to achieve sub meter aircraft position accuracy. Learned a lot about converting between different datums and projections. Lately, in retirement I have been having fun with RTK receivers.
Mark

I know how to make maps from LIDAR DEM and orthoimagery, but not very much about how it is captured. That must have been a fascinating career! I think there are a lot of changes in how all of this is done, thanks to inexpensive drones and advanced software however. I was "discussing" ways to use AI in my workflow to georeference historical aerial imagery with Gemini, after realizing that I needed to start thinking about it in a different way (in a way that leverages what computers are good at and humans are not).

Recently, I spent weeks georeferencing about 400 photographic plates of 1970's aerials in a traditional way, by matching features on 1980's imagery that I already have. That was a tedious process that took around 20 minutes per plate but still wasn't as accurate as I would have liked. Thinking about how AI might help, I realized that I could just give an AI the whole set of plates, have it match features between them and create a big mosaic - without having any clue as to the geographic coordinates. It would just make one big image, then that could be georeferenced afterwards. The problem is, it would get very expensive to upload all the data to the cloud and pay for the resources that AI uses to combine the imagery.

Gemini agreed that this was the right approach, but pointed me to free open source linux software that i could run on my own server. This might be slower than using the resources of a big data center, but it's free and what's the hurry? I can just let it churn away for hours doing its thing. Have been busy with other things, but will circle back to this in the future. Gemini would just guide me through the process, which is something I can do with a $5/month subscription.

One of the cool open source project that supports this kind of thing is called openDroneMap (ODM)

https://www.opendronemap.org/odm/

On the national level, I've talked with several NGS (National Geodetic Survey) employees. I actually do volunteer work for the NGS by locating and "recovering" US coast & geodetic survey benchmarks (USCGS). It's been a hobby of mine for many years. I post new location details, handheld GPS coordinates and photos of the benchmarks I locate on their website.

https://geodesy.noaa.gov/surveys/mark-recovery/index.shtml

I met a crew about 10 years ago at a benchmark location. They were using high quality Trimble equipment to "Bluebook" the benchmark location to a high degree of accuracy, usually within a quarter inch or better. I found it an excellent way to test the accuracy of my handheld GPS receivers. I posted an FAQ on the process here:

http://www.poi-factory.com/node/53299

Useful, thanks!

My impression is that pure un-assisted GPS can't get that kind of accuracy, ever.

My impression is that the route to super-accurate positions partly employing GPS involves differencing--from a "known" position, with equipment located at both the "known" location and the one for which one desires a really good position.

Is that what they were doing? Where was the "known" location.

I'm not an expert but I have talked to several surveyors in the area. All seem to prefer Trimble GPS equipment, which can achieve 10 mm accuracy with a clear horizon. RTK and known location points are also used when a clear horizon isn't possible.

https://geomaticslandsurveying.com/trimble-gps-equipment/