Long-term goal
In geodesy, a long-term target is a clearly visible survey point which, because of its height, is either
- offers a good (indirect) line of sight between distant points,
- or can serve as an auxiliary point for precise orientation of the theodolite .
In the first case, the coordinates of the long-term destination ( church tower , high chimney , high-voltage mast, summit cross ...) do not necessarily have to be known if the high point can be integrated into a network by means of suitable measurements .
In the second - more frequent - case, the distant target (at least 1 kilometer) is used to stabilize a polygon course or a very local survey, which would otherwise not be precisely defined in its direction due to short distances. The practical process is that you only measure the far point when working in the field , while the evaluation proceeds in two steps:
First, the local measuring points are evaluated approximately (i.e. their Gauß-Krüger coordinates are calculated), then all the observed directions to the long-term target with this Measured preliminary position and compared with the (slightly "pivoted") measured values. Because the long-term target is much further away than the next measurement points, the "pivoting" (usually less than 0.01 °) can be reliably corrected.
In navigation there are comparable methods for iterative improvement of positioning , but different terms are used.