Georeferencing means that the internal coordinate system of a raster image, like a digital map or aerial photo, can be related to a ground system of geographic coordinates. Thus, we can make it appear “in place” in GIS.

We’ll use an archaeological map of the area around Xanten, with the Roman base camps Vetera I and ||, and the Roman city of Colonia Ulpia Traiana, so we can work with its geographical data.