Neighborhood accuracy
In geodesy and in geometric applications of the compensation calculation, a measure of accuracy is referred to as proximity accuracy, which describes the mutual accuracy of neighboring points or measured values.
In a survey network , a distinction must be made between its large-scale and its local accuracy. In modern networks, the former already reaches a few centimeters per 100 km and is therefore more precise than a millionth (<10 −6 ). A few centimeters at distances of a few hectares or kilometers, on the other hand, make up a relative error of 10 −4 , which is immediately noticeable in the accuracy of today's measuring instruments. The (inherently unavoidable) small contradictions are particularly unpleasant when a larger area has been surveyed in several parts (“ operations ”) and the geodesist is just at the border of two operations. Then when a measurement is connected to two fixed points originating from different operations, a few centimeters of deviation, which are individually within the measurement tolerance , add up to a difference of 6 to 10 cm in a single distance.
If, for example, a number of streets are re-measured in the course of construction projects , a large area within can be reduced or increased by a few square meters as a result of such gaps . In order to avoid such effects of unfavorable neighborhood accuracy - especially in areas with high property prices - larger operations are now calculated “in one go” and the individual parts are subjected to a joint adjustment.
Similar effects of local discrepancies or exceeding of technical tolerances can e.g. B. occur in construction or when repeatedly attaching prefabricated parts .
See also
literature
- Dirk Donath: Building survey and planning in the existing stock , Chapter 6. Vieweg-Verlag, Wiesbaden 2008
- Heribert Kahmen: Surveying, 19th edition, De Gruyter-Verlag, Berlin and New York 1997 (especially chapter 8, determination of position points)