Our local Auditor??s Office just issued a new ordinance requiring plats of more than 5 lots to have certain layers in dwg format and to be located the following ??coordinate system?:
NAD 1983 HARN StatePlane Indiana East FIPS 1301
i have only goggled a little bit so far. ?ÿSeems a little bit strange GIS~ish wording. ?ÿThe HARN notation is a little curious to me. ?ÿI do not know what FIPS stands for.
I hope this is equivalent to what I call:
NAD 83 Indiana State Plane Coordinate System, East Zone
FIPS
Federal Information Processing Standards
FIPS is a national standard.?ÿ
HARN datums are dependent on the state. Go to NCAT and click on the datum link midway down:
Looks like the HARN datum for Indiana was published in 1997:
NCAT can give you the nominal differences between HARN and current?ÿ NSRS NAD83(2011)[2010.00] values. Depending on the project, you might want to transform or not before submitting.
My experience is that the difference even way out here in the PNW is still less than the auditor's GIS folks will even notice. If they get snippy I will point out that their required datum is 20+ years out of date and does not align with the current NSRS.
My experience is that the difference even way out here in the PNW is still less than the auditor's GIS folks will even notice. If they get snippy I will point out that their required datum is 20+ years out of date and does not align with the current NSRS.
I'll buy you coffee and even a scone for doing that.?ÿ Not enough people push back on the snippy GIS people.
We're all supposed to be working on the same goals.?ÿ?ÿ
Not enough people push back
I am non-confrontational, to an extreme.?ÿ It is just who I am.?ÿ I do like to watch a good fight sometimes in a movie, though, or to listen to Kenny Rogers sing about one.
I'm?ÿ a big scary strong safety/linebacker sized guy, so I'm careful to not be confrontational unless absolutely necessary.
that being said, when I am forced to to be confrontational, something is off the rails....
HARN (High Accuracy Reference Network) points are similar to NAD27 monuments. They are actual monumented locations that are to be accessible and are usually older monuments with good elevations such as first order bench marks. They were occupied and placed into the data base as pre OPUS/CORS locations which could be used by local and government surveyors to continue to densify NAD83. There should be a number of them "nearby". Ours are spaced about 30-50 miles apart and often are along little used county roads. To truly "get-on" HARN you need to occupy the actual points. They should be up-dated to newer coordinates shown on a data sheet, but that doesn't mean they were reoccupied.?ÿ
I always think of the HARN system as a system of physical locations with good recorded Geodetic values. The real value to me of them is they usually are bench marks so they are often superior to OPUS/CORS for a NAVD 88 number.?ÿ
However, to use the HARN system for the basis of Geodetic ties is a mid 1990's plan. To do it you really should occupy at least one of the monuments and check how the data sheet relates to it with OPUS/CORS.
Also it's not proper to refer to the Indiana system as the NAD 83 Indiana State Plane Coordinate System, East Zone.
It should be referred to as the "Indiana coordinate system of 1983, east zone".
Sorry that's how the DOT would red-line our plan sets when we were doing lots of control for them. States actually created statutes to properly name the state coordinate systems and that's what I see on Justia Law for Indiana. IC 32-19-1-3.
I would confirm that language since it was a quick Google search for me.?ÿ
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A good explanation, except that I don't see the relationship to NAD27.?ÿ HARN is an old realization of NAD83 and a LOT closer to the latest NAD83 than NAD27 is to NAD83 (<1 foot vs 100 ft in some areas)
I don't get involved in precision location of points, but I do use GIS in connection with real estate taxes in my role as a justice of the peace in Vermont. If I were asked to follow a standard, I would research the authority of the entity that is trying to impose the standard, and compare that to any state statutes that might prevent the local entity from imposing the standard. For example, our state has a statute about what to call the state plane coordinate system and how it is defined.
It appears our state's statute will become obsolete when the new datums described (but not named) on this NGS page are issued.
A good explanation, except that I don't see the relationship to NAD27.?ÿ HARN is an old realization of NAD83 and a LOT closer to the latest NAD83 than NAD27 is to NAD83 (<1 foot vs 100 ft in some areas)
Transformations of HARNs to later realizations of NAD83 are also more rigorously defined, especially since legacy observations were often included in later readjustments. Running NCAT will show transformation uncertainties are pretty small, and very consistent across typical project areas.
NGS has some good docs on the topic here and here. The first deals specifically with HARN-to-CORS relationship, the second has a very good section breaking down everything from NAD27 to NSRS2007.
@bill93?ÿ
The relationship to NAD27 isn't mathematical, but it's that they are physical geodetic monuments. I wouldn't try to relate coordinates between them even though there are rough conversion programs to do that. I don't understand why you thought that since I explained it.?ÿ
HARN (High Accuracy Reference Network) points are similar to NAD27 monuments. They are actual monumented locations that are to be accessible and are usually older monuments with good elevations such as first order bench marks.?ÿ
Someone there is using Esri software or data that came from Esri software because the name is straight out of the Esri projection engine. We included the FIPS zone numbers in some state plane definition names because customers were used to using them in the prior software, ArcInfo Workstation. If I remember correctly, the FIPS for the State Plane zones didn't become official, but people used the numbers anyway.?ÿ
In Esri parlance, NAD 1983 HARN usually means the first re-adjustment of a state post-NAD 1983 (86) and the "xxhpgn" grid files published by NGS to move from the original NAD 1983. States that did second or third re-adjustments were unhappy with us that we didn't have any transformations supporting those. Those grid files only came out a few years ago.?ÿ
Melita
@rover83?ÿ
Don't forget this document on the last nationwide adjustment?ÿ https://www.ngs.noaa.gov/web/surveys/NA2011/?ÿ
See also the former NGS Chief Geodesist's discussion of NAD83(2007) here:
https://www.ngs.noaa.gov/PUBS_LIB/NSRS2007/NSRS2007Analysis.pdf
Most USC&GS/NGS monuments were EITHER horizontal or vertical NOT both. Until the advent of satellite-based positioning the emphasis when siting horizontal monuments was intervisibility NOT accessibility. Siting of benchmarks was to find "permanent" locations that met spacing requirements.?ÿ Lots of BMs next to power poles, near railroad lines and set vertically in courthouses and the like.?ÿ ?ÿ
Interrogating the NGSIDB for published sites with both high accuracy horizontal positions and second-order or better NAVD88 heights, I find surprisingly few. Perhaps things are different where you work.
As for accessible monuments, it was lots more fun packing to mountaintop sites than driving to points along roadways. Maybe it is me but I always seemed to find pack times to be rather optimistic...
You also write: "The relationship to NAD27 isn't mathematical, but it's that they are physical geodetic monuments. I wouldn't try to relate coordinates between them even though there are rough conversion programs to do that."?ÿ ?ÿ
After the completion of NAD83(1986) (the original version of NAD83 that did NOT include ANY GPS) tools were developed to mathematically relate it to NAD27. Internal program like LEFTI and CLUSTER were more rigorous than the NADCON tool but were intended for expert users. NADCON was developed to support GIS and other lower accuracy applications. NADCON was later modified to account for the HARN surveys. If you read the NADCON documentation it recommends readjusting original observations with the updated adjustment coordinates.
NCAT was developed after my time but takes advantage of improvements in modeling and data. Relationships between the more recent versions of NAD83 are much easier to determine and model.
For me, the definitive reference for NAD83(1986) remains https://geodesy.noaa.gov/library/pdfs/NOAA_PP_NOS_0002.pdf
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Yes, but when one uses NCAT to convert between NAD83 and NAD27, one should look carefully at the uncertainty numbers. Here's a simple one from Piedmont NC, with NAD27 as the input:
There's both an ellipsoid change and a change in assumptions involved, and that makes a tough hill for any conversion mathematics to climb.
With one exception all the HARN points locally were placed on Bench Marks, I think they were all first order, although the one on the mountain might not have been, I don't think that line was a first order bench run.
There was one that happened to be a first order Triangulation point and a first order bench mark so it has good NAD83, NAVD88, NGVD29 and NAD27 numbers. No doubt it's very rare to find that combination, two other NAD27 triangulation points are bench marks. One is a first order bench mark and a second order horizontal point (it was removed during construction recently), the other is a first order horizontal point and a second order bench mark.?ÿ
I figured using bench marks when possible would be a nation wide policy, but like you say most bench marks aren't very good for GPS points since they are full of multi-path or awkward to occupy. Here in the big open it's easier to find them I would imagine.?ÿ
The idea that there were elevation points with good GPS values was helpful in the early days of GPS but it became way more important when Geoid models became more accurate. As the HARN points lost value for horizontal control when CORS was densified they became more important since the NAVD88 values could be more utilized. The HARN points were clearly better as elevation points than the CORS points.
Still today we occupy the main HARN point because of it's elevation value, in fact it normally will check across town to nearby bench marks using Geoid18 less than .05' with an RTK check, often .02' or less, and the last PPK check I did with it was .01' using Geoid18 and holding the NAVD88 value of the HARN point. We need to set some drone photo-control tomorrow and will use a combination of CORS and a first order bench mark to get values. It's been a while since I've looked at the accuracy vertically of the local CORS point so it will be interesting to see where that comes out.?ÿ
While I wanted to point out the tools available to transform data between datums, I would not use these tools for surveying. As the documentation for the old NADCON tool advises, the best way to put a point into the new datum is to resurvey it or adjust it using the original observations and the coordinates updated for the fixed control.
As for the problem of dealing with multiple records for a point in a data sheet, I like to use the example of AH1762. This is a Cooperative Base Network (CBN), a Height Modernization Station as well as a Tidal station. It has participated in a number of projects.
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Examining the ?ÿdata sheet we see a predictable improvement in ellipsoid heights due to improvements in receivers, antennas and processing software. While comments in this thread refer to the HARN surveys, the impetus for a subsequent campaign known as the FBN, was to improve ellipsoid heights that were not well determined in the HARN campaigns. For example, antenna phase models were not part of the HARN surveys. https://www.ngs.noaa.gov/PROJECTS/FBN/
This data sheet also shows a questionable decision at NGS to supersede a well-determined NAVD88 orthometric height (first-order class II) first with a third-order height then with values based on an ellipsoid height and geoid model. Note that superceded values are listed in descending data order.
AH1762 is on a barrier island and impacted by some slow coastal faulting. Note as well that someone has labeled this point as unsuitable for GPS observations. Sheesh??
As you know coordinates also change as a result of the choices made during adjustments.?ÿ
Note as well that someone has labeled this point as unsuitable for GPS observations. Sheesh??
That may have become the case long after the GPS observations?
AH1762'RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 2018 (JDW)
AH1762'NOT GPS OBSERVABLE, OVERSHADOWED BY PALM TREES.
@bill93?ÿ
The orange paddle marks station "DAISY" (AJ8169) near my home . When it was established in the 1990's, by GPS observation, it was in the clear. That building in the background didn't even exist until about 1995.?ÿ Shown in 2016:
And in 2019:
There would have to be quite a bit of logging done to make this GPS-able in 2022.
