Research On Simplification And Aggregation Algorithm Of Island Polygon In Electronic Chart

Along with the gradual development of electronic chart technology, its application domain expands unceasingly. In the background of the specific application of the electronic chart for path planning in the flight vehicle route where the islands are the main obstacles, this paper makes the thorough research in view of the islands' simplification and aggregation. As the vector electronic chart uses a series of separated spot data to describe islands, the goal of islands' simplification and aggregation lies in reducing the data point of describing islands and the number of islands as far as possible, reducing the computation complexity of implementing the route design using the islands data, and raising the application efficiency.In view of the islands' characteristics of different shape and complex curve, this paper has carried on detailed analysis to the shape characteristic of islands, proposed the islands' recognition method based on moving in a straight line around the paragraph direction and the islands' whole shape recognition method based on convex hull, then established the effective mathematical model to implement the reasonable expression of the islands' shape. First, the paper carries on comparative analysis to many kinds of classical curve simplification algorithms and chooses the Douglas-Peucker algorithm as the basic islands' simplification algorithm model. Then, in order to satisfy the specific application fully, some improvement to the fundamental model are made. For the sake of improving the implementation efficiency of algorithm, this paper has studied the realization method of the improved algorithm, and proposed the practical, feasible, high efficiency realization method. In islands' aggregation aspect, We has conducted thorough research in view of the examination method of the conflict between the neighboring polygon and the islands' aggregation method, then proposed the method of analyzing the conflict relationship between islands based on building constrained delaunay triangulation net, and solved the difficult problem of detecting collision among polygons. This paper also proposes "the tangent evolvement" algorithm as the method of islands aggregation. In this way we can obtain satisfying aggregation results which conform to the application condition by controlling the evolution threshold value.We use the simplification and aggregation algorithm of island that proposed in this paper and adopt data from the actual electronic chart to simplify and aggregate islands, after that we analyze the accuracy and the rationality of the new algorithm. Through the actual application example, the new algorithm is proved valid and progressive.