Datum Shifts

Shifting coordinates from one datum to another uses a set of equations. 

The datum shift with the Molendenski transformation must always be done in Lat/Long coordinates.  For UTM coordinates, they are first projected to Lat/Long, converted to the new datum, and then converted back to UTM.  The magnitude of the shift depends on which type of coordinates are used.  In the continental United States,  Lat/Long coordinates vary by up to 100 meters, in a rough bull's eye pattern about Michigan.  This is the difference between where the same lat/long coordinates project in NAD27 and NAD83.  UTM coordinates in the United States everywhere differ by more than 200 m, depending mostly on latitude, although the change does not differ as much by location as the Lat/Long shifts.

Last revision 8/20/2007