Map transformations

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)

Other map transformations used are:

1. Robust Helmert
2. Huber estimator
3. Vestimator and
4. Hampel estimator