Assessing the Planimetric Accuracy of Historical Maps (Sixteenth to Nineteenth Centuries): New Methods and Potential for Coastal Landscape Reconstruction

摘要

Historical maps are vital tools for landscape reconstruction from the late medieval period onwards. However, the planimetric accuracy of local and regional maps before the nineteenth century is often considered problematic. This paper proposes a method for the evaluation of these maps, through integration in multiple computer programs such as ArcGIS, MapAnalyst and statistical software (SPSS). This method has been tested on a sample of historical maps depicting coastal landscape change in an area at the present-day Dutch-Belgian border (ranging from the local to the supra-regional level and from the sixteenth to the nineteenth centuries), and variations in planimetric accuracy over time have been interpreted. Results point to an exceptionally high accuracy of earlier medium- and large-scale maps - scale being the first determinant of planimetric accuracy - since no significant rise in accuracy over time was found. Notwithstanding this overall accuracy, many maps display pronounced local distortions. However, rather than disqualifying maps for landscape reconstruction, systematic analysis of these distortions can help to facilitate the interpretation of the historical maps and their use for landscape reconstruction. Finally, a method for integrating map accuracies in landscape reconstructions based on multiple maps is proposed and illustrated.