A Novel Evaluation Approach for Line Simplification Algorithms towards Vector Map Visualization

Line simplification is an important method in the context of cartographic generalization, which is helpful for improving the visualization of digital vector maps. The evaluation method for the simplification algorithms is still an open issue when facing applications of vector data, including progressive transmission, web mapping, and so on. This paper proposes a novel evaluation approach for line simplification algorithms based on several factors towards vector map visualization, including the features of displays, map scales, and the ability of the human eye to distinguish pixels. In order to ensure the evaluation of the line simplification algorithms is conducted under the consistent strength of simplification, a measurement approach for the difference between an original line and its simplified one is proposed in this study, and the method of solving the appropriate simplification threshold is presented. With this method, four simplification algorithms are evaluated at five map scales using three evaluation indicators: standard deviation, compression ratio, and simplification time. The experiment and results show the evaluation approach in this study is feasible, and represents a good means in which to facilitate the application of line simplification towards progressive transmission and visualization of vector maps.