Cartographic Representation of the Italian Coasts: Analysis of Deformations Due to the Chosen Map Projection

Several scientific, technical and practical applications concerning the Italian coasts require the use of a unitary cartographic representation of the entire area. It is therefore necessary to select not only the geodetic datum itself, but also a single cartographic projection. This article aims to identify, among different possible solutions, the cartographic projection capable of guaranteeing minimal deformations. In fact, each projection introduces distortions (e.g., to distances, areas, angles between directions). In relation to the objectives pursued, a projection that limits or even nullifies the values of a specific type of deformation (for example those on areas or angles) may be preferable. It is clear that a study of the variability of distortions is useful: tools available in Geographic Information Systems (GISs) are suitable for this purpose. In this article the following representations, all conformal (i.e., without angle deformations), are considered and analysed using QGIS software: Universal Transverse Mercator (UTM) based on a single zone for the entire area considered, Mercator of the world, Mercator with one standard parallel, Lambert Conformal Conic with one standard parallel. The experiments demonstrate that UTM is the most suitable for the Italian coastal zones to limit both area and distance deformations preserving the shape.