**MAP TRANSFORMATIONS**

Map transformation involves transformation of points from one map to points on another map while minimizing the differences between the two sets of points.

- The '
**Helmert transformation**' is the best choice for the vast majority of applications. - The '
**Helmert transformation**' translates the points of one map horizontally and vertically and also rotates and scales the points (**it uses 4 parameters**). - The '
**affine transformation**' is useful in cases where the paper has pronounced**directional shrinking**due to orientation of the fibers. - The '
**affine transformation**' is also useful to**compensate for some shearing**in the map or for computing the shearing angle. - The '
**affine transformation**' with**five parameters**translates points in the x direction and y direction, a rotation and two scale factors (one in the x direction and one in the y direction) - The '
**affine transformation**' with**six parameters**consists of: - translation in x direction
- translation in y direction
- two rotation and two scale factors (both axes are rotated and scaled separately)

- Robust Helmert
- Huber estimator
- Vestimator and
- Hampel estimator