Okay, so maybe this is a dumb (ignorant) question, but I don't mind admitting my ignorance concerning ESRI Products (I'm just a dumb surveyor, not a GIS Expert).
I have a client that needs a .prj file in order to get a recent Project (NAD83(2011) Epoch 2010.0000) into their database. They sent me a .prj file relating to the Coordinate System, Datum, Projection, that they are using (NAD83 UTM Zone 12);
Here's the "header" data from their .prj file (reformatted for clarity);
PROJCS["NAD_1983_UTM_Zone_12N",
GEOGCS["GCS_North_American_1983",
DATUM["D_North_American_1983",
SPHEROID["GRS_1980",
6378137.0,298.257222101]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]],
Okay, this appears to be a somewhat generic "definition" that leaves the question of NAD83 Realization (1986, HARN, 2007, 2011 etc.) open to interpretation. The variance between NAD83(1986) and NAD83(2011) is a non-trivial consideration IMO, but maybe I'm just splitting hairs.
I guess that my real QUESTION is...DOES ESRI have options embedded in the Software, that "handles" the DIFFERENT realizations of NAD83?
If so, what is EXACT ?ÿtext I need to replace;
GEOGCS["GCS_North_American_1983",
DATUM["D_North_American_1983",
with?
Thanks in advance,
Loyal
Loyal,
This is what I got from ArcGIS 10.2.2 with regards to the NAD83 2011 projection data.
NAD_1983_2011_UTM_Zone_12N
WKID: 6341 Authority: EPSG
Projection: Transverse_Mercator
False_Easting: 500000.0
False_Northing: 0.0
Central_Meridian: -111.0
Scale_Factor: 0.9996
Latitude_Of_Origin: 0.0
Linear Unit: Meter (1.0)
Geographic Coordinate System: GCS_NAD_1983_2011
Angular Unit: Degree (0.0174532925199433)
Prime Meridian: Greenwich (0.0)
Datum: D_NAD_1983_2011
Spheroid: GRS_1980
Semimajor Axis: 6378137.0
Semiminor Axis: 6356752.314140356
Inverse Flattening: 298.257222101
I see no difference in values, but I am not wearing my reading glasses.
I do see differences in the text.
Looking at the .prj file they provided you, they are not working in NAD83 2011.
I have had some projections that are sensitive, and some that are not.
I do not know for certain if the various iterations of the NAD83 datum are accounted for with each projection listed.
MKennedy on GIS Stack Exchange could answer this question, and she might even be here.
Michael Dennis wrote prj files are specifically referenced to the NAD 83(2011) epoch 2010.00 realization. Any particular ??realization? of NAD 83 results in an associated set of coordinates on the stations that provide access to the datum, without changing how the datum is related to the Earth. The projection parameters and reference ellipsoid (GRS-80) are identical for all realizations of NAD 83. In principle, lines of lati- tude and longitude are the same, but the coordinates differ due to the how they are determined, as well as to motion (such as plate tectonics). The NAD 83 realization is therefore associated with the data. If the data are referenced to NAD 83(2011) epoch 2010.00, that will result in coordinates at a point that differ from other realizations. The realization is a critical part of the metadata, but it has no effect on the map projection parameters. That is, the relationship between latitude and longitude and the LDP (or State Plane) northings and eastings is the same for all NAD 83 realizations.
?ÿ
To me this means the prj definition is good for all realizations. You could have two different coordinate pairs for the same point in the GIS depending on the realization however. Does this help??ÿ
?ÿ
Hi,?ÿ
So far we have generic definitions for the various NAD83 realizations: NAD 1983, HARN, CORS96, NSRS2007, 2011, PACP00, MARP00, PA11, MA11 but not yet the ability to include a specific epoch / date on the definition. We're working on it.
Here's the well-known text string for the NAD 1983 (2011) UTM zone 12N projected coordinate system:
PROJCS["NAD_1983_2011_UTM_Zone_12N",GEOGCS["GCS_NAD_1983_2011",DATUM["D_NAD_1983_2011",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-111.0],PARAMETER["Scale_Factor",0.9996],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0],AUTHORITY["Esri(EPSG)",6341]]
and here's the one for the geographic coordinate system:
GEOGCS["GCS_NAD_1983_2011",DATUM["D_NAD_1983_2011",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433],AUTHORITY["Esri(EPSG)",6318]]
Melita
Disclosure: I work for Esri.
Thanks folks (especially Melita), that's exactly what I thought to be the case.
Loyal