The Orthophotomap of Lublin 1944: from Luftwaffe photographs to map application – idea, methods, contemporary challenges of processing and publishing archival aerial photographs

Abstract The origins of aerial photography can be traced back to the second half of the 19th century, and periods of World Wars contributed to the development of techniques for developing and disseminating aerial photographs for military purposes. In the literature, we find descriptions of the Polish Military Geographical Institute’s (WIG) use of aerial photography to update topographic maps of nearly 40% of the country’s area at the time. Unfortunately, the fate of the pre-war collection of photographs is difficult to establish. Given this, the aerial photographs from the period of the Second World War (German and Allied) constitute the oldest possible complete and consistent photographic documentation of Poland. The series of German prints (373-GXPRINTS) collected at the National Archives and Records Administration in College Park (NARA, USA) are maintained according to the most liberal policy on access and further use. At the same time, the organisation of the NARA archive and the extent to which the collection has been digitised (over one million images) leave a deficiency, and searching for images requires knowledge, methods and experience. In 2020–2021, the Department of Geomatics and Cartography of the Maria Curie-Skłodowska University implemented the project Development of the Ortophotomap of Lublin 1939–1945 (NCN, Miniatura 4.0. No. 2020/04/X/HS4/00382). The result of the project is a dedicated web portal https://ortolub.umcs.pl, consisting of a digital repository of aerial images, a map application and standardised GIS raster data services. The author believes this is a unique source base, with unprecedented detail. The publication of the project results under the Creative Commons CC-BY-SA 4.0 licence is intended to foster the widest possible use of wartime aerial images in scientific research and popularisation activities. The process of developing a historical orthophotomap, as presented in the article, is universal and can be repeated on any set of aerial photographs. At the same time, development work is needed to automate the operations as fully as possible. In conclusion, current challenges and prospects for the development of historical orthophotomaps of national coverage are indicated.