Abstract:

Modern maps drawn using scientific surveying and mapping technology are precious historical geographical data source, directly showing land cover information in the past. Digitization is a necessary way to extract the historical land cover and its changes from old maps. This paper proposes an old map digitization method based on machine learning and image morphology analysis, and takes the “Eastern China: Shanghai” map as an example to elaborate its implementation process and verify the effectiveness. Results show that the method can fully utilize the color information and morphological information in the map, and extract the surface water information quickly and accurately in a semi-automatic manner. The proposed method can be applied to the digital extraction of land cover information with color characteristics in most color modern maps. It shows great potential to provide both data and method basis for accurately restoring land cover changes and understanding the evolution in man-land relationship since modern times.

Key words: digitization of old maps, modern Shanghai, surface water bodies, machine learning, image morphology