Abstract
The detection method determines 7 parameters of the map projection, a map rotation is involved. It is invariant against all map parameters, the scale, shifts, and rotation.
It solves a situation, when the analyzed map is rotated due to the incorrect insertion into the scanner, or a switched orientation of the page (portrait vs landscape). For futher initial guess x0, the method has a slower convergence.
The optimizing procedure is based on the hybrid BFGS. The method is also applicable to early maps.