Sampling-Based Multi-Level Representation of Plotting Curves on Web Map

With the development of the Internet and the enhanced rendering ability of browser end, electronic map based on the Internet, which is called web map, has been visited and plotted by more and more users. Normally, the representation of the plotting results such as the markers and curves are changed with the map level, and the traditional method is to take a strategy to select the composition points. In this paper, instead, an adaptive sampling method of plotting curves which preserves the characteristic points is proposed and a relationship between map level and the number of sampling points is established based on the Radical Law in cartography. Experiments are conducted to compare the proposed sampling method with others to validate the simplicity and accuracy. The result indicates that the proposed method can realize the sampling of plotting curves on the web map at different levels in terms of simplicity and accuracy for the multi-level representation.