Abstract: Without taking polyline global structure into consideration, current polyline tessellation methods tend to make low quality decomposition. It makes them difficult to support vector mapping with large dataset and dynamic mapping with high update rate. This paper proposed a polyline momentum function and designed a monotone decomposition and tessellation method. The monotonous increasing intervals of the momentum function, as the gradient intervals of polyline, are divided continuously into optimized triangle strips. The monotone decreasing intervals of the momentum function, as the mutational intervals of polyline, are divided discretely into optimized triangle fans. The experiment results show that the decomposition quality measured by the numbers of triangulation vertices, triangles and primitives using this method are better than that based on vertex and line segment and can significantly improve the drawing efficiency for polyline. This method is also applicable to closed, width gradient and smooth line style.

Key words: polyline, symbolization, monotone decomposition, tessellation, polyline smoothing