Fetching

Anfeldung is a technical term coined by Karl Ledersteger around  1940 for the amalgamation of the geodetic surveying networks of neighboring regions or countries into a larger, uniform network. The prerequisite for this is a geometric overlap, i.e. H. the existence of common "identical points" at least at the national borders .

The main problems that arise and their most important solution steps are:

1. Inconsistent geodetic datum , ie different central points and calculation areas instead of a mean earth ellipsoid
   • Solution by means of "ellipsoid transition", ie slightly modified projection of each individual measuring network (" triangulation ") onto a common mathematical surface
2. Small contradictions in the orientation (alignment to astronomical north ) or in the network scale of the subnets, which in older measurements can be up to 0.001 ° or a few cm per km
   • differential rotation and expansion / compression of each subnetwork, each of which is introduced as an unknown in an overdetermined adjustment. The orientation is particularly accurate when there are Laplace points .
3. Small contradictions at the borders (identical points have slightly different geographical coordinates in the two countries )
   • Applying the coordinates as common unknowns , the coincidence of which is a conditional equation of the network calculation.

The Anfelderung is generally based on the exact compensation calculation by the method of least squares (largely eradicate the small, unavoidable contradictions) and the projection on a geodetic astro- clearly bearing reference surface (usually the reference ellipsoid of the largest country when it is reasonably central in the whole network) .