Pickup point

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Pick- up points  (AP) are fixed position points that condense the TP network of the lowest order (usually 4th order) and - together with these trigonometric points - enable measurements to be coordinated with the higher-level reference system for national surveying . A distinction is made between 1st and 2nd order pick-up points, with the latter - in analogy to the TPs - representing the higher compression level.

APs should be placed in such a way that they are in public space and can be easily seen from different directions. A typical place is the footpath at a street crossing.

determination

Pick-up points can be determined with the help of polygons , classic single point determination or satellite geodesy ( GPS ). Since the latter method allows determination accuracies that are independent of the order of the respective AP and is therefore increasingly used, the distinction between 1st and 2nd order APs is gradually becoming less important.

Fuse

In order to be able to locate a pick-up point in the location again, the distance ( tension ) to prominent topographical points such as building corners, masts, fence pillars, etc. must be measured with decimeter or centimeter accuracy. Distances to three such backup points are set to within five millimeters for restoration.

Furthermore, the angles on the AP are determined in the resulting security triangles in order to ensure sufficient testing. The security points must not be in the same danger zone as the AP itself. If the marking of the AP is lost, one of the security points can be declared the new AP, which in turn requires the above-mentioned work steps.

presentation

The dimensioning sketches are made according to the crack regulations applicable in the respective federal state and are called AP maps or AP descriptions . A5 and A4 formats proved to be useful (see also point description ). Pick-up points that were used for a property survey are to be shown graphically in the continuation plan as well as in the head of the plan ( legend ). The deck breaks of the DGK5 or, in the new federal states , the  TK10 serve as an AP overview . The different orders and determination accuracies can be highlighted in the AP overviews with appropriate symbols.

In island maps admission points were shown as they were essential as the start and end points of measurement lines for manual mapping of the card's content. In today's common frame maps or in the inventory of ALK data, APs are more informative.

Others

Occasionally, pick-up points served as boundary points . This is problematic as re-branding the AP requires border negotiation with the affected owners. Nowadays one avoids such double functions of survey points .

Historically, APs served as an instrument point for recording the new points ; today, in the time of the free stationing , only the network connection . Therefore, the term “pick-up point” is currently taking a back seat in favor of “connection point” - while keeping the established abbreviation AP.

In Thuringia , recording points are called cadastral  fixed points (KFP), and the survey sketches are accordingly called KFP description .

Individual evidence

  1. ↑ The length of these polygon sides and thus the distance between the recording points varies between 50 m to about 1 km. (Heribert Kahmen, surveying, 19th edition, Berlin; New York: de Gruyter, 1997, p. 335, ISBN 3-11-015399-8 )

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