New algorithm on merging graphic elements of ENC

In order to improve the efficiency of path planning and auto collision avoidance of unmanned surface vehicle (USV), the standard electric nautical/navigational chart (ENC) needs to be simplified. This paper introduces a universal algorithm for merging graphic elements of ENC. The algorithm focus on the merging operation on polygonal lines and polygons, as while as the binary tree search algorithm is utilized to solve the merging problem of the enclosed areas after the first merging operation. The proposed algorithm can easily be adapted to Boolean operations between regions composed of other shape sets.