GENERALIZATION OF DIGITAL TOPOGRAPHIC MAP USING HYBRID LINE SIMPLIFICATION

A cartographic line feature is a succession of segments with various geometric and visual properties. Thus, it is useful to segment and enrich the line data in order to apply the best algorithm and the appropriate parameters to each section. In this study, a hybrid method of line simplification that combines two different line simplification methods is proposed and applied to a topographic map. This method consists of three steps. First, it analyzes the relationship between the characteristics of lines and the error resulting from the application of the existing simplification methods. Second, it segments line features based on the analysis and allocates a suitable line simplification method which produces minimal positional errors on each segment by using expansible moving window. Finally, it applies the allocated simplification algorithm on each segment and merges all of the segments. During the test of the proposed method, 1:1000 scale topographic maps are generalized to a 1:5000 scale map. The simplified results are then analyzed by vector displacement. The results show that the hybrid line simplification method outperforms the two earlier line simplification algorithms.