Extracting and Identifying Point Symbols Based on Distance Transform

A new method for extracting and identifying pointshaped symbols of scanned topographic maps based on map algebra is presened.The extracting results of element maps are optimized and the lines which do not meet the features of point symbols are filtered according to curve density and line density.Weighed distance function,and identify symbols using the method of template matching are put forward according to the function results.The algorithm can work out the problems of extracting and identifying point symbols in the condition of character & line conglutination or complex background,and it achieves a high level of recognition accuracy.