This kind of monitoring, where possible, is increasingly present in the controls of large structures.

The total stations available today, especially those of the robotic type, allow acceptable accuracy for many types of structures. These are instruments capable of automatically (or manually) detecting the position of a point, generally materialized in a reflecting prism, with respect to one or more fixed reference points. The instrument determines the position of the point (and therefore its variations over time) by measuring angles and distances. Since it is an absolute measurement (even if we are interested in relative values), it is clear that the precision of the result depends greatly on the distances between the total station and the point to be checked, on the atmospheric conditions, and on the number of measurements taken.

The measurement is not extremely precise, but if the instrument is kept in a fixed location and connected to a data processing platform, then the continuity and redundancy of the measurements, the selection and processing of an enormous quantity of data, can give measurements that approach 1-2mm of precision (only for measurements taken in automatic and continuous form). Trimble and Leica products are remembered for this. We, for our part, use these products for total stations, while we offer our products for the materialization part of the fixed and mobile points with 360° prisms, normal prisms with L-shaped support, leveling benchmarks, rod signals, bases for sights, prisms, target points, and miscellaneous.

The controls with GPS, which we can always include in the topographic controls, instead exploit the satellite control of the points. The instruments on the market today allow, with fairly relative figures, to obtain satisfactory results, if not always at a quantitative level, at least at a qualitative level, i.e., they allow the trend of the horizontal movements of a point to be obtained with a precision of a few millimetres.