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Experimenting “fisheye-lens functions” in studying digitally particular historic maps

2012; Professor Emer. Evangelos Livieratos; Volume: 7; Linguagem: Inglês

1790-3769

Chrysoula Boutoura, Angeliki Tsorlini, Vassilios Tsioukas,

Satellite Image Processing and Photogrammetry

Summary Historical maps are rich in the way their cartographic content is represented both in the geometric - projection component of the representation and in the thematic counterpart. Focusing into the geometric content of old maps, we can identify exceptional examples of maps designed in par- ticular projections of non-conventional types, as they are e.g. the bird-eye view projections re- lated, in general, to the perspective representation, or the more complicated fisheye view projec- tions, which is the very interesting case of some rare and thus important old city maps. Dealing with the second case of representations, the projection properties are not known and the only evidence which could assist the analysis is based on an initially intuitive approach, associ- ated to the phenomenological assimilation of the map geometry pattern. The analysis can only be based on a test-and-trial procedure, i.e., by comparing the degree of agreement of the original map with models developed using relevant mapping functions which are generally known in the modern photographic image capturing literature as fisheye-lens functions. In this study the fa- mous city map of Argentoratum (Strasbourg) is used, in digital form, taken from Braun and Ho- genberg's Civitates Orbis Terrarum (1572) in order to study the apparent non linear projection, of a fisheye view type, of this map. A digital analysis using types of appropriate fisheye lens functions, combining cartographic and photogrammetric methods, shows the projection type in- herent in the map representation, in association to a comparative study using relevant modern maps in regular projections.