ESRI vs EPSG Which State Plane Coord System To Use in the USA?

If you are working with a large area, the state plane coordinate zones may not be appropriate because each is tailored to reduce distortion in that particular area and the coordinates do not match at the boundaries.?ÿ So Universal Transverse Mercator may be better.

If you are working in a small area, the particular SPC zone (California 1,California 6, etc) that covers that area may be the best choice.

With any of those projections, you need to be aware that the zone is projected on a flat plane that does NOT usually align with the elevation in the area, so a significant ground/grid ratio of distances may apply.?ÿ That is why people sometimes generate a custom Low Distortion Projection to cover the area of interest.

And you need to know what horizontal datum [NAD83(86), NAD83(HARN, NAD83(2011), etc.] your lat/lon or north/east coordinates are in.?ÿ The differences in those horizontal datums will usually be on the order of centimeters or fractions of a foot.?ÿ NAD27 as seen on the USGS topo maps will be different by 10's to 100's of feet.

Once you have all that figured out, you can then pick the corresponding number from the ESRI or EPSG list.

there is no "best"
what does the Consumer want? Ask, and present the options
What are the record values of the monuments used for field control?

I prefer Metric but that drives most Americans nuts.

In California most local agencies will dictate/desire a datum... go with the flow, but Always provide full metadata

Great feedback.?ÿ Let me pose the question a bit differently then.

For my example for California Zone 6, assuming the site area is 50 acres and is not near a Zone boundary, Imperial, not metric measurements, what would you say would be the most common coordinate system that an RPLS is using for a topo survey of that size if all surveyors were polled? (what EPSG or ESRI number?)

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ECEF

@andy-j

🙂  I was asking for best guess on a specific EPSG (or ESRI) code.  Just curious what people would guess.

EPSG, however ERSI should be using EPSG projections.?ÿ EPSG provides the metadata to 'move' to other projections and can be back checked.?ÿ I don't be ERSI puts out how they 'move' from projection to projection.

ERSI 'local' projections parameters are not necessarily found in EPSG.

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@bradl

Yes I have learned that.?ÿ When I look up ESRI numbers though I can't find a website that tells me which EPSG that ESRI is using.?ÿ?ÿ

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So I guess what I'm asking is which EPSG # would probably be most commonly used out of the 6 different EPSGs for Zone 6 listed on this page?

https://spatialreference.org/ref/?page=1&search=California+Zone+6

And then the second question would be, what EPSG is used for ESRI 102646??ÿ Looks like it's 2230 based on this discussion:

https://gis.stackexchange.com/questions/242684/unknown-srs-in-geoserver-for-nad-1983

I see EPSG 2875 is similar but I'm not sure what the difference is between that and 2230.?ÿ What is HARN? Are 2875 and 2230 essentially the same coordinate system? I think HARN is updated and more accurate version??ÿ So why would you even ever use 2230 instead of 2875?

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Disclosure: I work for Esri on coordinate reference systems. I'm also a member of the Geodesy subcommittee that maintains the EPSG registry.

spatialreference.org is crowd-sourced. If you're looking for EPSG information, you should go directly to http://www.epsg-registry.org. However, if you're looking for a well-known text version of a coordinate reference system, EPSG registry will give you version 2 of the WKT standard which is not supported in a lot of software yet, including Esri's.?ÿ

Esri's algorithms should match EPSG's if we support that particular projection. We've never had any complaints about Lambert conformal conic in California!

Melita

@consultant

By going to EPSG.io and searching 'NAD83 California' it shows many coordinate reference system.  Those reference systems are all different realizations of the NAD 83 datum. 

You appear to be looking for the commonly used definition of NAD83 to use in a State Plane projection, and as others have said, it depends. 

What I mean is, some NAD83 is based on the NSRS2007 (3500), others based on HARN (2875). (NGS does a good job of explaining the difference between NSRS2007 and HARN: https://www.ngs.noaa.gov/NationalReadjustment/ )

I would say the default realization is NAD83 (2230).  

Unlike most of the rest of the US, California is very dynamic so the different realizations will make a difference in location.  If I were to use 3500, when I needed to use 2230, my state plane coordinates would be roughly 1' different, because the difference in time.

If you open the .PRJ and review the how the projection is created you can typically find what projection you'd need.

You can also develop your own projection if you're looking to map a small area.  (The folks with our DPW department had this done : 7132)

Hope this helps

Well if a surveyor was having to submit a Record of Survey to a county, such as San Diego County, of course the answer to my question is, whatever the county required.?ÿ However I just looked up the ordinances in San Diego County and they specify:

"CALIFORNIA COORDINATE SYSTEM" means the coordinate system as
defined in Section 8801 through 8819 of the California Public
Resources Code. The specified zone for San Diego County is "Zone
6" and the official datum is the California Coordinate System
(CCS 83), based on the "North American Datum of 1983".

The public code says:

Zone 6 coordinates shall be named, and, on any map on which they are used, they shall be designated as ƒ??CCS27, Zone 6 or CCS83, Zone 6.ƒ?

On their respective spheroids of reference: (1) the standard parallels of CCS27, Zone 6 and CCS83, Zone 6 are at north latitudes 32 degrees 47 minutes and 33 degrees 53 minutes, along which parallels the scale shall be exact; and (2) the point of control of coordinates is at the intersection of the zoneƒ??s central meridian, which is at 116 degrees 15 minutes west longitude, with the parallel 32 degrees 10 minutes north latitude.

So @Bradl I find what you say about the 1-foot difference hard to believe because there are obviously more than one EPSG with NAD83 projection, yet the law is not that specific, so if there was indeed a 1-foot difference between different EPSG for Zone 6 that use NAD83 projection, this would cause inconsistency in the surveys submitted to the county that were not all using the same EPSG.?ÿ?ÿ

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@consultant

I don't have a clear or simple answer to that either.
"Imperial" has various flavors. International Foot and US Survey Foot.

then, the Epoch is Very significant.  Fault line and Pate boundaries.
I suggest you partner with a Land Surveyor local to your project, and make darn sure that he/she/it is very conversant with geodetic matters

@consultant  

Some things, like the @Bradl statement, are easy to check. Consider NGS mark AA7159 in Riverside County, CA, which is in California Zone 6. The Inverse calculation between the NAD83(2011) lat/lon and the superceded NAD(1992) lat/lon is shown below.

The ellipsoidal distance between the two realizations of the same point are 0.6119 meters, or just over 2 feet apart. If points stood still, or measuring precision never improved, there would be no need for all of those different projections. That's not the case, though, so we have to know what we're doing when we compare values.

The ellipsoid and its parameters are the same in both projections. The point, however, is positioned at different coordinates on that ellipsoid for the two realizations. There's no way the state can anticipate such changes, so it defines coordinate systems in terms that remain constant.

That's why a statement describing what you used is so important and one reason why NGS went to so much trouble to develop NCAT.

Output from INVERSE

   
  Ellipsoid : GRS80 / WGS84  (NAD83)        
  Equatorial axis,    a   =    6378137.0000
  Polar axis,         b   =    6356752.3141
  Inverse flattening, 1/f =  298.25722210088
   
  First  Station : AA7159 2011                   
   ---------------- 
    LAT =  33 57  2.01393 North 
    LON = 117 26 11.56252 West  
   
  Second Station : AA7159 1992                   
   ---------------- 
    LAT =  33 57  1.99902 North 
    LON = 117 26 11.54678 West  
   
  Forward azimuth        FAZ = 138 39 36.1337 From North
  Back azimuth           BAZ = 318 39 36.1424 From North
  Ellipsoidal distance     S =         0.6119 m

I thought @Bradl was referring to a potential difference (1ft he mentioned) between two EPSG codes that are both using NAD83.?ÿ The example would be EPSG 2230 and EPSG 2875.

I apologize if my questions have not made sense.?ÿ I'm not a Land Surveyor.?ÿ?ÿ

Regarding the county requirements, and my original intended question, which is, which one would you use for the county requirements, 2230 or 2875 or does it not make a difference since they are both NAD83??ÿ If it doesn't make a difference as far as meeting the county requirement, then what is the difference between EPSG 2875 and 2230? There has to be SOME difference otherwise why have separate EPSG codes?

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@consultant

I should have been more clear in stating if I used the epoch of 3500 (2007), I would get 1' different that if I used the current epoch. 

The definition of those two projections, appear to be the same.  This does not change the fact that state plane coordinates move, because California (and the rest of the world) move. 

EPSG 2230 and 3500 are the definition of those projections.  EPSG states 2230 has an accuracy of 4m, while 3500 has an accuracy of 1m, while 2875 has .1m.  Their definitions may be the same, but the stations they validated the projection against are probably different.

Consistency comes from using acceptable control with Geodetic Coordinates published by the NGS or CRSC. The definition of NAD83 (legal or EPSG) won't necessarily change per the different projections, however projections are just a way of making a round object flat. So there is inherent error whenever using a projection.

It sounds like you are getting too caught up with EPSG, when you need to be focusing on the epoch as others have stated.  Are you trying to set up a coordinate system in Civil 3d?

@bradl

I would think given multiple options that meet county requirements at any given time, you'd want to go with the coordinate system with the highest accuracy, which in this case is EPSG 2875.  Does that make sense?

@consultant

To me it would make sense if my survey was tied to HARN monuments, or HPGN as they are typically called here in CA.?ÿ The reason it has such high accuracy is because it only references specific passive stations.

If you are just projecting NAD83 Lat & Long on the current epoch, I would suggest using 2230.

See the definition below (important to look at the datum and authority info):

EPSG: 2875

PROJCS["NAD83(HARN) / California zone 6 (ftUS)",
    GEOGCS["NAD83(HARN)",
        DATUM["NAD83_High_Accuracy_Reference_Network",
            SPHEROID["GRS 1980",6378137,298.257222101,
                AUTHORITY["EPSG","7019"]],
            TOWGS84[0,0,0,0,0,0,0],
            AUTHORITY["EPSG","6152"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9122"]],
        AUTHORITY["EPSG","4152"]],
    PROJECTION["Lambert_Conformal_Conic_2SP"],
    PARAMETER["standard_parallel_1",33.88333333333333],
    PARAMETER["standard_parallel_2",32.78333333333333],
    PARAMETER["latitude_of_origin",32.16666666666666],
    PARAMETER["central_meridian",-116.25],
    PARAMETER["false_easting",6561666.667],
    PARAMETER["false_northing",1640416.667],
    UNIT["US survey foot",0.3048006096012192,
        AUTHORITY["EPSG","9003"]],
    AXIS["X",EAST],
    AXIS["Y",NORTH],
    AUTHORITY["EPSG","2875"]]


EPGS: 2230

PROJCS["NAD83 / California zone 6 (ftUS)",
    GEOGCS["NAD83",
        DATUM["North_American_Datum_1983",
            SPHEROID["GRS 1980",6378137,298.257222101,
                AUTHORITY["EPSG","7019"]],
            TOWGS84[0,0,0,0,0,0,0],
            AUTHORITY["EPSG","6269"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9122"]],
        AUTHORITY["EPSG","4269"]],
    PROJECTION["Lambert_Conformal_Conic_2SP"],
    PARAMETER["standard_parallel_1",33.88333333333333],
    PARAMETER["standard_parallel_2",32.78333333333333],
    PARAMETER["latitude_of_origin",32.16666666666666],
    PARAMETER["central_meridian",-116.25],
    PARAMETER["false_easting",6561666.667],
    PARAMETER["false_northing",1640416.667],
    UNIT["US survey foot",0.3048006096012192,
        AUTHORITY["EPSG","9003"]],
    AXIS["X",EAST],
    AXIS["Y",NORTH],
    AUTHORITY["EPSG","2230"]]

I'm terribly sorry if I have only confused the issue.  It make sense in my head, but even I don't like to be in there too much!   :wink:  ?ÿ

@consultant

So why not use EPSG:6317? It corresponds to NAD83(2011), the most up to date state plane projection.

Have you tried multiple EPSG definitions and noted the differences?

@mathteacher

Sounds good to me.?ÿ Interestingly the website didn't show that one when doing a search for "California Zone 6" because it's tied to Puerto Rico but then lists a gazillion US States along with it.?ÿ If it's more appropriate for wide-spread usage including official county records in California, then it seems to make sense to use the latest data.?ÿ But I thought though an EPSG specifc to a more localized area would be preferable?

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@consultant

Try EPSG:6425 or 6426 which are the projected CRS for California zone 6 based on NAD83 (2011). The first uses meters. The second uses US survey feet.