27.3. Helmert 2D |
Also known as 4-parameter similarity transformation. The transformation process involves 3 steps: scaling, rotations and translations. The first two are defined by one parameter each and the translations include 2. At least two pairs of points are necessary.
Formulas:
where:
x', y' = Transformed X, Y coordinates
x,y = Original X,Y coordinates
S = Scale
= Rotation angleTx = Translation X
Ty = Translation Y
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