Experiences on georeferencing of maps from the XIX century Gregorian Cadastre of Bologna (Italy)

The study focuses on the nineteenth century Gregorian Cadastre of Bologna, kept today at the State Archive of the city. In these maps the city is divided into several sectors; for each sector there are ground floor maps and maps for the floors above and below. In the study, results from metric analysis of these maps are reported. The analysis consists in a preliminary georeferencing of digital images derived from high quality scanning of the original documents, together with an assessment of map deformation. Moreover, digital mosaics from each floor were sequentially superimposed. Finally, a comparison with the original edition map kept at the State Archive of Rome was performed, in order to highlight possible differences between the two editions and digitally restore the worn maps of the Bologna edition.