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NAD83 to NAD83 HARN Florida transformation seems off

Question asked by keithaddison on Oct 15, 2019
Latest reply on Oct 16, 2019 by joel_cusick

Depending on which transformation I use I get inconsistent results when converting points from NAD83 Florida State Plane East (SPE) (the vanilla 1986 one) to NAD83 HARN Florida State Plane East.

 

The below graphic was made by clearing the data frame coordinate system so I can get a visual on the projection differences.  (ie to get rid of the on the fly projection) The big blue dot is the original point in vanilla NAD83 SPE.  The green dot is the same point in NAD83 SPE HARN, projected using the NAD_1983_to_HARN_Florida transformation (which is the one Arc suggests)  The magenta dot is the same point in NAD83 SPE HARN but transformed using the WGS_84(ITRF00)_To_NAD_1983 + WGS_1984_(ITRF00)_To_NAD_1983_HARN transformation.  There's 1.5' of difference between the two, why do they differ?

 

I've been comparing different transformation from NAD83 SPE to other non-HARN realizations, and I'm increasingly suspect of the transformations that involve HARN when used as an intermediate, they seem to give inconsistent results when compared to transformations that don't involve HARN and use WGS84 as in intermediate instead.

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