Find datum transformation parameters 

Select transformation method 
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This second page of the Datum transformation parameters wizard allows you to choose the method you wish to use to calculate the datum transformation parameters between the two sets of control points.
The concept of each calculation method is shortly explained.
Dialog box options:
Geocentric datum shift: 

Calculates the translation vector (dX, dY, dZ, i.e. differences in geocentric coordinates in meters) between:
so that the pointcoordinates of the first point map can be transformed to the second. 

Molodensky: 

Calculates the translation vector (dX, dY, dZ, i.e. differences in geocentric coordinates in meters) between:
so that the pointcoordinates of the first point map can be transformed to the second. 

Bursa Wolf: 

Calculates translations (dX, dY, dZ, i.e. differences in geocentric coordinates in meters), calculates rotations (Rot X, Rot Y, Rot Z in microradians and in arc seconds), and calculates the scale difference factor (dScale) between:
so that the pointcoordinates of the first point map can be transformed to the second. 

Compute scale and rotations first: 

When you selected the Bursa Wolf or the Molodensky Badekas method:


Molodensky Badekas: 

Calculates translations (dX, dY, dZ, i.e. differences in geocentric coordinates), calculates rotations (Rot X, Rot Y, Rot Z in microradians and in arc seconds), and calculates the scale factor (dScale) between:
so that the pointcoordinates of the first point map can be transformed to the second. 

Xo, Yo, Zo: 

When you selected the Molodensky Badekas method, you must specify a rotation center.

When you click the Next button, you will go to the Output page where you can inspect, and optionally save, the calculated datum transformation parameters.
The general process of the calculations is presented below. Conversions take place between map coordinates, latlon coordinates on the (local) ellipsoid, and geocentric coordinates.

Geocentric coordinates are XYZ coordinates (in meters) where the center of the earth is taken as 0,0,0. Figure 1 below shows the octant of the world where the XYZgeocentric coordinates are positive.
The geodetic latitude is larger than the geographic latitude due to the ellipsoidal flattening as the perpendicular onto the ellipsoid does not pass through the center of the ellipsoid.
The formula to perform the Bursa Wolf datum transformation reads:
The formula to perform the Molodensky Badekas datum transformation reads:
where:
t_{x }, t_{y }, t_{z }  are the translations between both datums (in geocentric coordinates). 
a, b, g  are the rotation angles between both datums; rotations about the X, Y and Z axes respectively. On the Output page, a, b, g are called Rot X, Rot Y, and Rot Z. 
d  is the scale difference between both datums. On the Output page, d is called dScale. 
 
X_{0 }, Y_{0 }, Z_{0 }  is the rotation center of the local datum (in geocentric coordinates). 
I, II  are the local and global datum respectively (geocentric coordinates). 
See also: