Use Of Lidar Data In The 3d/4d Analyses Of The Krakow Fortress Objects

The article presents partial results of studies within the framework of the international project "Cultural Heritage Through Time" (CHT2). The subject of the study were forts of the Krakow Fortress, which had been built by the Austrians between 1849-1914 in order to provide defence against the Russians. Research works were aimed at identifying architectural changes occurring in different time periods in relation to selected objects of the Krakow Fortress. For the analysis, the following LIDAR (Light Detection and Ranging) data was applied: Digital Terrain Models (DTM), Digital Surface Model (DSM), as well as the cartographic data: maps and orthophotomaps. All spatial data was obtained from the Polish Main Office of Geodesy and Cartography (Glowny Urzad Geodezji i Kartografii - GUGIK). The majority of the cartographic data is available in the form of Web Map Services (WMS) on Geoportal (www. geoportal.gov.pl). The archival data was made available by the Historical Museum of the City of Krakow, or obtained from private collections. In order to conduct a thorough analysis of objects of the Krakow fortress, DTM and DSM data was obtained, either in ASCII format, or in the source *. las (LIDAR) format. On the basis of DTM and DSM, the degree of destruction of selected fortress objects was determined, occurring as a result of the action of demolishing those objects in the interwar period (1920-1939) and in the 1950s. The research has been made on the basis of all available cartographic materials, both archival (plans, maps, photos) and current (topographic map, orthophotomap, etc.) ones. Verification of archival maps and plans was carried out by comparing current digital images of the existing forms of fortifications with designs developed by the Austrians. As a result, it was possible to identify the differences between the original design, and the current state of the objects concerned. The analyses, which have been conducted, also allowed checking the legitimacy of locating the forts in terms of the object visibility from the enemy's side (foreground), presence and number of "dead fields" in the foreground, the effectiveness of blurring characteristic military forms by means of masks formed from tree rows and shrubs. Furthermore, the analyses involved examination of the impact of erosion resulting from the natural process of silting drains of forts' ground forms, as well as processes of obliterating of the slopes, sliding of the scarps, and flooding of moats and caponieres.