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I'm quite a ways outside my box on this one, but I would ceratinly appreciate any perspectives on this issue. I have some control points from NGS that are in NAD83 (NSRS 2007) that I would like to merge with the rest of our control point dataset, but our existing data are in NAD83(CORS 96) ... I think ... or it could be NAD83 (2001). Perhaps I should ask:

Which NAD83 is inherent in ESRI's NAD_1983_StatePlane_Georgia_West_FIPS_1002_Feet coordinate system (Geographic: GCS_North_American_1983 Datum: D_North_American_1983)?

In any case, does anyone know of any transformations for converting NAD83 (NSRS 2007) to one of the "regular" NAD83 datums? NGS will not be publishing any, and ESRI does not have a transformation filter for it. Any help would be appreciated. BTW, I did read the GIS-SE posts from last year regarding NAD83<-->HARN conversions, but I am wondering if anyone has dealt successfully with this issue since then.

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2 Answers

up vote 3 down vote accepted

Esri added HARN/NSRS2007, NSRS2007/WGS84 and CORS96/NSRS2007 transformations to ArcGIS 10.0, but they're all 'bookkeeping'--parameters are zeroes. I think you would have to get a geodetic surveyor to calculate a transformation by running a least squares fit using control points in both systems. I know of two cities on the west coast that have done so.

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thanks ... not what I wanted to hear, but thanks. Might you have any good references on how I might go about calculating the transformations myself? OPUS maybe? I have, I think, only seven control points that I need to transform, but they are critical ones. Thanks again for the help. –  celticflute Sep 1 '11 at 13:31
    
@celticflute I don't have the knowledge or background, I'm afraid. Particularly in this case, when the differences are very small. –  mkennedy Sep 1 '11 at 16:33
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In regard to the first question.
The vertical datum is managed seperately from the horizontal in Esri.
When configuring a new feature class check the "will contain Z values" and then there is another tab next to coordinate system "z coordinate system".

Picture1

And on existing feature classes with z enabled.
The dialog looks similar.

Picture2

The second question...
I can think of a way to accomplish it. As to the accuracy I cannot speak.
1. Create a personal or file geodatabase,
2. Create a feature data set and
3. define the target crs and vertical system,
4. create an empty feature class
5. using the original data to define the schema of the target feature class.
6. Use the load cammand to load the original data into the target feature class.

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Brad, I can't figure out why you brought heights (z) into it! celticflute is asking about the 'horizontal' datum. –  mkennedy Aug 31 '11 at 20:56
    
@mkennedy NAD83 (NSRS 2007) is an elevation datum as is CORS96. –  Brad Nesom Aug 31 '11 at 21:32
    
true, they're 3D but with ellipsoidal heights, not elevations (NAVD88 elevations have not been adjusted). I think we just have a terminology issue. –  mkennedy Aug 31 '11 at 23:55
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@Brad, thank you, your procedure above does work, and the "transformation" is done automatically; however, mkennedy is correct in the answer below; the internal transformations are "bookkeeping" only. Coordinates don't actually change ... bummer ... and me without the number for a geodetic surveyor programmed on my cell phone. –  celticflute Sep 1 '11 at 13:26
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