Analytical methods for the projective content of Coronelli’s central Europe maps

Historical cartography constitutes a factual basis for a diachronic analysis of the city, land an places. Historical maps often contain information that cannot be found in other written sources, such as, for example, place names, boundaries, and physical characteristics that have been altered or completely erased by modern development. Analyzing historical maps makes it possible to understand the territory’s current configuration – which is the result of choices made in the past – and to critically assess evolutionary dynamics. The interventions of the past influence the present-day conformation in the same way that today’s interventions may someday influence the future. The development of information technology has recently allowed an evolution in the methods of investigation and dissemination of historical maps, thanks to the introduction of intuitive and immediate interfaces, giving immediate access to complex functions and making them easier to be used than they were in the past. Generally, we are witnessing to a wide spread of new applications, even in disciplinary fields traditionally not involved in computer science, which are characterized by the simplicity in managing complex analysis and by the presence of tools for the visualization of results from a non expert wide public. Descriptive and cognitive aspects of historical maps can be emphasized in a system where historical, geographical or economic data can be integrated; this tools, which are able to relate heterogeneous information in order to increase and improve their management and communicability, represent, in our time, the basic equipment for every research. This paper deals with the Europe maps of Coronelli, contained in the Atlante Veneto, and wants to better understand which is the projective system better suitable to these historical cartography. Recently a collection of ancient maps was found in the Institute of Marine Sciences of CNR in Venice. The collection includes maps, perspective views, pilot books, atlas (such as the Coronelli’s one that was used for the projective analyses) and ancient manuscripts: this work took into account a selection of maps and documents representing the Venice Lagoon, the Adriatic coast and a part of Europe. The first part of this research focused on the application of a scientific method for digital acquisition of historical cartography; thanks to the Geomatic tools and especially to digital photogrammetry it is possible to acquire metric, semantic and symbolic information and also the three-dimensional shape of the geometrical support to correct the deformations occurred over time. The applied procedure of recovery and valorisation of historical cartography is divided into three different phases: acquisition, georeferencing and data elaboration of maps in a digital environment. This paper underlines the application of a scientific procedure for the conservation and valorisation of the historical Cartographic Heritage, particularly considering the geodetical and projective content of european maps of Coronelli: as often stated in literature, most of the maps are topographically not accurate, especially regarding the north-south orientation (mainly because the magnetic declination was not known yet), and the projective system is not well defined. The georeferencing process and the residual analyses can offer some considerations on this topic.