Identification of digital elevation annotation in scanned map

It has been several years since the research of vector topographical map, and there have been some progresses in this field. However, most of the researches focus on the identification of contour lines; ignoring another important element of the map - the spot elevation. As a kind of element of map, the spot elevation is rather like a single point. It should be of significance to the comprehension of map, combining with the contour lines. By analyzing the features of annotation of the contour and elevation point, the paper gives a method of identifying the elevation annotation of a scanned topographical map and discusses the principle of the method, including separating character series on the basis of morphological translating and splitting of the individual character based on the vertical projection. Finally, the performance evaluation is presented.