Encoding and querying historic map content

Abstract

Libraries have large collections of map documents with rich spatiotemporal information encoded in the visual representation of the map. Currently, historic map content is covered by the provided metadata only to a very limited degree, and thus is not available in a machine-readable form. A formal representation would support querying for and reasoning over detailed semantic contents of maps, instead of onlymap documents. From a historian’s perspective, thiswould support search for map resources which contain information that answers very specific questions, such as maps that show the cities of Prussia in 1830, without manually searching through maps. A particular challenge lies in the wealth and ambiguity of map content for queries. In this chapter, we propose an approach to describe map contents more explicitly. We suggest ways to formally encode historic map content in an approximate intensional manner which still allows useful queries. We discuss tools for georeferencing and enriching historic map descriptions by external sources, such as DBpedia. We demonstrate the use of this approach by content queries on map examples.