Instead of subclassing "NavigationDataToNavigationDataFilter" and calculating the transform by it's own, the filter now subclasses "NavigationDataLandmarkTransformFilter" and provides the source and target points for the registration to it. The registration itself is done by the "NavigationDataLandmarkTransformFilter".
One or more NavigationDatas can be set to the "NavigationDataReferenceTransformFilter" and if there are less than 3 datas the filter calculates the rest of the required points for the landmark transform.