Research On Cartographic Generalization Method Considering Local Accuracy

GIS(Geographic Information System)is a computer system used to input,store,query,analyze and display geographic data.It inherits the knowledge of geography,surveying and mapping,map,information,communication and many other subjects.It is a comprehensive technology of interdisciplinary.In recent years,with the development of geographic information system,the demand for map data information is increasing.Automatic cartographic generalization has become a hot topic in the field of GIS,which is the difficulty and development direction of cartographic automation.Map generalization is mainly based on the basic principles of cartographic generalization,relying on the basic database of geographic information,through the map generalization algorithm to select,simplify and summarize various geographic information elements,using the computer model processing to complete the automatic generalization of map information.The purpose of this paper is to improve the ability to maintain the local accuracy of the simplified curve on the premise of ensuring the contour features of the simplified curve.Based on this,this paper focuses on the vector map simplification method.The main contents include: the related concepts and development of map generalization are introduced;This paper reviews and summarizes the research status of this topic at home and abroad,introduces the line element simplification algorithm in detail,and analyzes its advantages and disadvantages;This paper focuses on the map curve simplification method based on progressive iterative approximation,which can not only maintain the overall geometric shape of the simplified curve,but also achieve high-precision approximation at the feature points while meeting the requirements of global error;Based on this method and the multi-scale characteristics of DP algorithm,the relationship between the simplification results and the map scale is analyzed and studied,and the multi-scale representation hierarchy of geographic information data is established;Based on the multi-scale hierarchical structure of geographic information data,the BLG tree is transformed.Finally,the progressive transmission method of vector map data is proposed.The experimental results show that the proposed map curve simplification method based on progressive iterative approximation has better expression effect,and the local accuracy can be greatly improved compared with the traditional algorithm;Based on this,the multi-scale expression structure has obvious level difference and good scale;The incremental transmission method can significantly reduce the waiting time and improve the efficiency of data transmission on the premise of meeting the user’s demand for map quality.