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WGS84 to NAD 83 Confusion

Question asked by Toddn51 on Apr 22, 2015
Latest reply on Jul 30, 2015 by jborgion

I don't think I'm understanding how the wgs84 to nad83 tranformations work.  I'm using ArcMap/ArcPad 10.


From a Gnss-enabled personal geodatabase my ArcPad project properties are:

- Projection = NAD_1983_StatePlane_South_Dakota_South_FIPS_4002

- GPS Datum = D_WGS_1984

- Datum Transformation = NAD_1983_To_WGS_1984_5

I post process thru Trimble GPS Analyst using the "reference positon from base provider" option.


Am I in the State Plane NAD83(1986) realization or a newer realization of NAD83(Harn) or (Cors96)?  The transformations differnces beteween the NAD_1983_To_WGS_1984_1 and NAD_1983_To_WGS_1984_5 options confuse me.  Wasn't sure if the _1 trans keeps everything in the NAD83(86) version and the _5 transformation places me in the later versions (Harn...Cors96)?  I check into published S. Dakota State Plane HARN control fairly well (about a half foot), which is about as accurate as our Geo XH can get.  I need to be on the State Plane NAD 83(Harn) system, so I may need to re-project my data and start using a  _HARN transformation.  Just need to figure out where I'm starting from first.


Any help is appreciated. Thanks, Todd