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Fundamental trigonometric network

Fundamental trigonometric network, carried out by triangulation and trilateration, consists of more than 20.000 vertexes divided in 4 orders and located every 5 km. It covers uniformly all Italy and was first set up between the Italian unification (1861) and 1919. Other national networks such as the Cadastral one are derived from it. This network has a relative precision of some decimeters in planimetry and in height.

Immagine 26x26 per link riguardanti l'acquisto di prodottiBUY ONLINE: Geoproducts

Grigio, 26x26 HOW TO BUY ONLINE: Read How to use the geographic search engine and How to buy a trig-point monograph

In the geographic search engine, trig-points are represented by red or blue squares. These different symbols are described below:


trig-point of uncertain definition

Every monograph of trig-points consists of a sheet of useful information concerning the point. In each information sheet are indicated:

  • name and specification: name of the point location, a specification can be added in order to better identify the place of materialization;
  • order: indicates the hierarchy of the determination. The order of importance can be decreasing: I, II, III, IV, Tp5 (checked topographic point), TP (topographic point), CC (established by the state border commission);
  • number: the point is identified by an univocal six-number code; the first three numbers indicate the sheet of the Italian map at scale 1:100.000 where the point is located, the last three numbers are the sheet sequential numbering and the forth number can’t be more than five.;
  • cartographic elements: cartographic elements indicating the point location, both in the old series at 100.000 and in its sub-multiple map at 25.000, and in the new series at 50.000 and in its sub- multiple element at 25.000;
  • administrative information: nation, region, province, municipality and Carabinieri station where the trigonometric point is located;
  • property: name of the owner of the plot of land or building, address included, where the vertex is located;
  • reference plane: description of the horizontal element the height refers to;
  • adjustment: information about the computation that provided the planimetric determination;
  • trig point data: geographic coordinates based on ETRF2000 and ROMA40, plane coordinates indicated in TM and Gauss Boaga systems and point’s height;
  • history: main events in the vertex’s history
  • materialization: description of the elements (objects or symbols) indicating the vertex;
  • access: how to get to the place where the vertex is located (if an authorization is necessary or if there is any restriction);
  • additional information
  • astronomical observations: if any astronomical observation was performed on the point;
  • description sketch: floor plan or perspective drawing representing the vertex and its surroundings;
  • last intervention: description of the last intervention on the vertex.

The following monographs are available:

  • Trigonometric points
  • Trigonometric points of uncertain definition (Materialization was approximately established or with an order inferior to III and established before 1940)