Sentripod makes use of retro reflective technology set on a cylindrical target.
Mounted within a rotor arm the target can be set vertically or horizontally for the most convenient sighting. Observation is achieved by direct sighting to the centre point with cross hair optics and laser/infra-red distancing.
By using Total Stations such as Trimble and Leica the measurement to the centre point of the target is achieved by applying a user defined 4.4mm constant to that of the instrument.
Whatever instrument is used the surveyor may initially test on measured base lines to ensure the degree of accuracy and repeatability required.