Georeferencing Historical Cartography: a Quality-Control method

Using historical cartography inside a GIS environment in order to realize long term change detection studies of a certain area is nowadays an established and fairly generalised occurrence. As is well known, the starting condition for making these land analyses is the thorough rectification of the historical maps digital format. This paper offers a methodology for creating a form of “accuracy assessment” for georeferencing executed on a historical map, based on a comprehensible control procedure with a reasonable completion time. The fundamental idea is to use a set number of points to measure the gap between their positions on a georeferenced historical map from the reality of the territory. The control procedure creates a series of parameters to be added as metadata on the georeferenced map. These are constituted by the mean error distance and standard consequential deviation, and the percentage of an area examined on a map, drawn from a control grid superimposed on it.