Comparison And Applications Of Automated Generalization Algorithms For Roads On Maps

In recent years，to automatic map generalization, people at home and abroad haveachieved a lot of success in many aspects，including quality evaluation model had beenestablished. At the same time, a large number of practical algorithms and models came outfrom the lab and a batch of automatic map generalization software had been developed.However, cartographic generalization involving multiple disciplines, for example,Cartography, computer science, mathematics, psychology, engineering and so on, mappingprocess has the characteristics, such as objective, quantitative modeling, algorithms,intelligent, systematic, and collaborative, and it is lack of strict quality assessment andmanagement system of automatic map generalization, as a result, it is very hard to realize thetrue meaning of "automation" completely.Because road network has many characteristics, including throughout the full map,diverse in shape, complex relationship, grade range and the use of high frequency inautomatic map generalization, Automatic generalization of the road network become a focusof research in the field of automatic map generalization and occupy a very important positionin the automatic map generalization in the total factor.Based on the principle of automatic map generalization and combined the research statusof automated generalization algorithms for road network on maps at home and abroad, Thispaper analysis mainly the principle of the three road selection algorithms, including theresearch of selective omission of road features based on topology, selective omission of roadfeatures based on mesh density for digital map generalization and a generalization of roadnetworks based on topological similarity, obtains some useful conclusions and promotes thedeveloping of automated generalization for road network on maps. The main contents of thispaper are as follows:(1)The basic concepts of the three road selection algorithms are introduced. Describe thefour principles which automated generalization algorithms for road netwo rk on maps shouldbe followed, they are the principle of topological constraints, the principle of geometricconstrains, the principles of structural and the principle of Gestalt constraints.(2)Discuss the basic principle of the three road selection algorithms completely. Therules which the every algorithm should be followed and the selection process are the point ofdiscussion.(3)Elaborate the basic connotation and some problems of quality evaluation of automaticmap generalization. Based on the basic principle of the three road selection algorithms, andthen combine the basic principles which automated generalization for road network on mapsshould be followed and the overall assessment strategy of the automatic map generalization, discuss quality assessment strategies of road selection algorithm based on the constraints, andnext analyse basis for this assessment and guiding ideology of quality assessment strategies,and the standards and emphases for the assessment are given.(4)Quantify the standards and emphases for the quality assessment strategies, andclassification and grading assessment indicators, geometric accuracy assessment indicators,topological consistency assessment indicators, structure morphology assessment indicatorsand applicable scope assessment indicators are given. Obtains some useful conclusions basedon experimentation by comparative analysis the three road selection algorithms based onthese five assessment indicators.