Elements of Cartography

Abstract

Cartography is of fundamental importance for all geographic data characterized by a spatial attribute, i.e. datum coordinates, as it provides a possible description of the shape and size of the Earth and its natural and artificial details. The role of cartogra-phy is to map geographic facts and phenomena (e.g. places) which are identifiable by their position and which can be georeferenced, archived and referred onto maps. The basic functions of cartography are • to give both a punctual knowledge of the territory, based on the observation of every single object, and a general one, for a global vision; • to allow and develop deductive and inductive logical processes, related by con-comitance, proximity, frequency, etc.; • to act as basic support for classification, planning and land management. A cartographic map is a flat, approximate, reduced and symbolic representation of the Earth's surface or of its parts. This is achieved according to systems, or representations , that turn ellipsoidal figures into plane figures and that, through appropriate signs, can reproduce information about the shape and measure of the ground elements, as well as the relative representation of real or abstract phenomena which can be located in space. A map is a cartographic product realized by integrating different disciplines and techniques. The phases of the cartographic process can be summarized as follows: • survey, selection and annotation of spatial data; • data standardization; • data generalization; • transformation of the points belonging to the terrestrial surface into the corresponding points on the reference surface (geoid: altimetry, ellipsoid: planimetry) through biunivocal correspondence. The terrestrial surface, and of the gravity field, is approximated by choosing a specific coordinate reference system; • representation of the reference surface on the map according to a cartographic reference system, namely the mathematical equations enabling one to represent the terrestrial surface on map plane or screen; • realization of the map, defining its typology, legend and symbols.