Editing historical maps: comparative cartography using maps as tools

Accurate European fine scale map-making was carried out from the late 18th century onwards, initially in France and then throughout the Austrian Empire. The first modern cadastral survey ever was the Napoleonic one (1809-15, 1:2.000) followed by the well-known Habsburg Cadastre (since 1817, 1:2.880). Both were the earliest modern cadastre. In this mainly methodological paper two related case-studies are presented: (i) the Napoleonic Cadastre at 1:2.000 scale (1809-1815) and (ii) the River Adige map (the so-called Nowack-Plan), a “cadastre-comparable” topographical map, contemporary (1803-1805) and at fine-scale (1:3.456), whereas the Habsburg Cadastre is used, for both case-studies, as a map as a tool. Thus, we are faced with cartographies composed of hundreds of map-sheets, with a lack of information about the native reference systems and mainly not yet georeferenced. In short, each map-sheet needs to be localizable (in a common reference system, ETRS89), avoiding a massive initial georeferencing/mosaicking process onto the whole data-set. Following this path, our current work centres on developing a methodology using the index-map sheet. The first case-study (the Napoleonic Cadastre) is characterized by a lack of index-map, so a new current one was implemented, fitting the grid of Habsburg Cadastre index-map. The second case-study (the Nowack-Plan) provides relevant index-maps, but no information about the native system, so we have georeferenced these index-map in the native system of the Habsburg Cadastre, successively performing the transformation in ETRS89, using the official parameters provided by the Region.