Spledeus asked a great question a couple of days ago about the next big adjustment of NAD83. It seems there will be no more big adjustment of NAD83, but a new datum, the Geometric Datum of 2022, which will also include a new vertical datum based on the Grav-D gravity measurements. This will be a great achievement for land surveyors because our datum will be in close alignment with the coordinate system of the GPS system (IGSxx/ITRFxx/WGS84). For example SBAS corrected positions (which are by nature consistent with IGSxx/ITRFxx/WGS84) will then be consistent with NAD2022. This could be particularly important as precise point positioning becomes more... well... precise.
When NAD83 was implemented, replacing NAD27, the State Plane Coordinate Systems were changed to reduce confusion. You'll remember that NAD83 and NAD27 are data (a reference ellipsoid and established geodetic coordinates of monuments on the ground) and that State Plane is a projection (this lat/long equals this grid N/E). So what happens in 2022? What change will take place with the State Plane Coordinate System?
Many States have already adopted county-wide projections which permit much less distortion than the larger State-wide projections. The change in datums (from NAD83 to NAD2022) seems like the optimum opportunity to nationalize this trend and to develop projections for every county in the United States.
> Spledeus asked a great question a couple of days ago about the next big adjustment of NAD83. It seems there will be no more big adjustment of NAD83, but a new datum, the Geometric Datum of 2022, which will also include a new vertical datum based on the Grav-D gravity measurements. This will be a great achievement for land surveyors because our datum will be in close alignment with the coordinate system of the GPS system (IGSxx/ITRFxx/WGS84). For example SBAS corrected positions (which are by nature consistent with IGSxx/ITRFxx/WGS84) will then be consistent with NAD2022. This could be particularly important as precise point positioning becomes more... well... precise.
>
> When NAD83 was implemented, replacing NAD27, the State Plane Coordinate Systems were changed to reduce confusion. You'll remember that NAD83 and NAD27 are data (a reference ellipsoid and established geodetic coordinates of monuments on the ground) and that State Plane is a projection (this lat/long equals this grid N/E). So what happens in 2022? What change will take place with the State Plane Coordinate System?
>
> Many States have already adopted county-wide projections which permit much less distortion than the larger State-wide projections. The change in datums (from NAD83 to NAD2022) seems like the optimum opportunity to nationalize this trend and to develop projections for every county in the United States.
I certainly hope it works, but the initiation of a county wide projection is already being confronted by resistance in my area. it probably happened with nad27 and nad83 in the same way. those that do not understand the benefits of a modern projection paired with modern instrumentation with appropriately fitting results, need to educate themselves. many will categorize the endorsement of a new projection as akin to needing burned at the stake.
i am hoping many of us publish carefully planned LDP's to be introduced with geometric 2022. many operations in this area are still clutching nad 83/91 in their cold, dying hands
I love the idea of a county based reference system, but I do not think it's completely feasible. It may work in the larger western states, but it would most likely cause chaos in small states, like mine (NJ).
From my viewpoint as an engineer, throwing (what amounts to be) 20+ reference systems at me would get tiresome and complex, especially when possibly involving projects that cross county lines (though I do not know how this is handled elsewhere in the country).
From my viewpoint as a land surveyor, scale factors are reduced greatly etc etc. I see all the benefits here.
In the end, I think it comes down to how well the engineering community accepts a new reference system.
Or maybe I'm just missing the point... if I am, anyone willing to show me the pros and cons of this?? :-S
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> In the end, I think it comes down to how well the engineering community accepts a new reference system.
>
It is time we surveyors grab life by any hanging part and tell the engineering community how the reference system will be delivered to them.
What about large western counties with large elevation differences? Consider Yellowstone County Montana for example.
Depending on your error tolerance, you will probably end up with 10 to 20 LDP's to cover this one county.
I certainly agree that for really flat places, it works like a dream.
But for large counties, or counties with large vertical relief you will end up with lots and lots of overlapping LDP's. Instead of having a separate system for each job, you might be able to group jobs by town.
If you had desktop and field software that realized that the earth was not flat (and I know that you already do have field software that does this), then you can just calculate a scale factor for every single vector and be done with it.
M
Why place yourself in any box. All I need is a consistent set of raw world coordinates. I can look at it how ever I wish from there or show it to any client in any manor they wish. So bring it on!
It was good to met you when you knew who I was!
Land Surveyors are minority users of reference frames. If we aren't careful Engineers will bypass us and get the data they need the way they want it...
If there isn't a rotational issue I'd think you could just redefine the origin point, say 500,000, 2,000,000 to be at the lat long in the 2022 version equal to be at the lat long in NAD83. That way the SPC coordinates would remain the same (or very close). The new lat long origin point wouldn't be some nice neat round number.
In my imagination SPC's by 2022 will be in the museum of data history, sort of like NAD27 is today. You will still need to deal with it from time to time, but it probably won't be an every day thing.
Considering my county is still using ngvd29, I am guessing they will accept the 2022 a few decades after I retire.
I am not yet 40.
>SPC coordinates would remain the same (or very close)
"Close" is how you create MAXIMUM confusion. Please use different false N & E values.
> From my viewpoint as an engineer, throwing (what amounts to be) 20+ reference systems at me would get tiresome and complex, especially when possibly involving projects that cross county lines (though I do not know how this is handled elsewhere in the country).
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Great comments. Projects that cross county wide systems would be no different than crossing State Plane Zones now. Pick a system and stick with it, even if part of the project does not lie in that zone. Some projects may not be suitable for the county wide system, in which case, a custom system tailor made for the project would be needed.
> What about large western counties with large elevation differences? Consider Yellowstone County Montana for example.
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> Depending on your error tolerance, you will probably end up with 10 to 20 LDP's to cover this one county.
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> I certainly agree that for really flat places, it works like a dream.
>
> But for large counties, or counties with large vertical relief you will end up with lots and lots of overlapping LDP's. Instead of having a separate system for each job, you might be able to group jobs by town.
>
> If you had desktop and field software that realized that the earth was not flat (and I know that you already do have field software that does this), then you can just calculate a scale factor for every single vector and be done with it.
>
Great comments, Mark. And all true.
I would envision that the scale factor for a county wide system would be weighted toward population, such that the greatest "elevation per capita" would be used. If users want to still employ numerous LDP's for a given geographic area for different elevation zones, those users would still be free to do so. A single scale factor for a county with a lot of relief would allow for some out of tolerance scale factors, but this is already the case for State Plane, so the county system gives up nothing to the State Plane System in this regard (in my opinion).
1
What I'm thinking is that you could replicate a SPC in the new 20122 system by setting up a projection with all the same parameters as the current SPC (false northing and easting, etc). The 2022 and NAD83 are not all that much different (a meter or so center of earth) same ellipsoid. There is some rotational difference. In your new replicated SPC you set the lat and long for the origin at the place in the 2022 system equal to the lat and long in NAD83. I don't think the coordinates you would see on a GPS controller would vary enough from the actual in NAD83 original SPC to make any real difference. Of course if you are a strict gotta be sub centimeter precise this is probably a no go for you. For most of my career, when ever the survey equipment put me down within a centimeter of a mark I have been able to recognize it.
But as I stated before I'm mostly indifferent to this. All I need is the real world coordinates (ECEF or lat, long, and Ht). It's easy to look at the data how ever you wish and in any projected coordinate system you like from this data. So I don't see this as any real big deal.
Also, there is no direct mathematical conversion from NAD27 to NAD83. I don't think this is so with NAD83 or the new 2022 system. Our computers will be able to handle it just fine. You probably won't want to do it with a hand held calculator but I expect the programmers will be able to accommodate us just fine.
This is an interesting topic/thread - lots of ideas are floated some good and some not so good. Good or bad, I invite serious consideration of the following:
1. Map projections are strictly two-dimensional.
2. We (surveyors and spatial data users) work with three-dimensional measurement systems, data, and models.
3. Low Distortion Projections (LDPs) are the source of great confusion for a number of reasons.
4. Rather than address all those reasons, please know that there is a better way.
5. As stated before and repeatedly, the global spatial data model (GSDM) provides all the benefits of a LDP while preserving the 3-D integrity of our data.
6. I'm giving a presentation on LDPs at the Colorado Surveyors Summit on February 26th. How many of you might be there?
7. Item #70 at the list of posted articles is a summary of LDPs. You should read it!
Have a great week and happy reading!
Whoops, I should have replied to the original post instead of here.
I think what you are proposing is a fine solution for users to adopt for themselves, but I don't think an official NGS option like this would be a good idea. Maybe I'm wrong. Converting between NAD83 and NAD2022 will be important (to that I agree) and it will be much, much more robust than NADCON was for converting between NAD27 and NAD83. So we agree there, too.
The solution you describe is not unlike what users have been doing with ITRF based coordinates in an NAD83 world for a while (particularly when using SBAS such as OmniStar and WAAS). It's messy though.
We're on the same page regarding Geodetic coordinates.
Beyond nice! I will post that picture in a separate thread.
You are exactly correct. The underlying database should be geodetic , our data collectors are fast enought to convert on the fly.
+1 x10
Mr. Burkholder,
I've visited your website several times. I can tell you know what you are talking about, but I've struggled to follow it entirely. The information you provide tells about what GSDM can do, but is kind of fuzzy on how it does it.
Perhaps I've not investigated it enough.
Is the software computing a projection on the fly for each origin point and then discarding it?
:good:
