An improved Douglas-Peucker algorithm aimed at simplifying natural shoreline into direction-line

The simplifying natural shoreline of vector data into direction-line is the basis of delineation of baselines of the territorial sea. Using classical algorithms of vector data compression, such as the Douglas-Peucker algorithm, to simplify the natural shoreline into direction-line, ignores the special requirements of a guarantee of national marine interests. To solve this problem, this paper proposed an improved Douglas-Peucker algorithm. Firstly choose the convex points of the natural shoreline as an alternative set of points; then filter segment points from convex points based on angle and distance; finally, divide the data into several parts in order to perform the Douglas-Peucker algorithm, and control the threshold of every part to effectively select feature points and protect national maritime interests. This paper uses ArcGIS 10.0, Visual Studio platform, and C# language to carry out the algorithm design, and choose a local coastline of Jiangsu province to conduct experiment. The results show that, compared with the Douglas-Peucker algorithm, the improved Douglas-Peucker algorithm improves the area ratio by 0.19%(0.17%-0.20%), and compression rate of coordinate points by 13.22% (9.48%-16.95%), and the accuracy of curve simplification also improved.