Leveling
The geodesist calls leveling and centering the process after setting up the tripod, on which the theodolite or total station is fixed exactly above the surveying or fixed point . The instrument is centered when the extension of the vertical standing axis runs through the floor mark of the fixed point.
The centering of the instrument is carried out with the help of plumb bobs :
The rough leveling of the instrument is done with the circular level , then the fine leveling with the tubular level on the theodolite (alidaden level). If their accuracy (2–5 ″ for pars values around 20 ″) is not sufficient, a rider level can be placed on the tilt axis of the instrument.
For leveling instruments with an inclination compensator, only a rough leveling is necessary, which is done with the circular level.
Precise leveling is also required for many other measuring instruments , e.g. B. in astrometry , gravimeter , lasers or in sewer and hydraulic engineering . It can also be done using built-in inclination sensors (1- or 2D), a pendulous height compensator , setting vials or, for special tasks, using a hose level.