Research On Key Technology And Implementation Of The Cartography Generalization In Global Geographic Information Processing Of Scale 1:4000000

Study of cartographic generalization is an effective way to improve the efficiency and quality of geographic information process.At present,the research of automatic cartographic generalization mainly concentrated in using large scale topographic map data to generalize medium and small scale topographic map data.The research of using small scale topographic map data to generalize the smaller scale geographic map data is less and there is still no a set of complete automation solution to solve the generalization problem.Nowadays the cartographic generalization is mainly by the man-machine interactive operation at low degree of automation,so how to make computer to simulate the thinking of the human to generalize geographic information data automatically is also a problem to be solved.With the map scale becoming smaller,the graphical features of geographical elements have had the great change and the small scale cartographic generalization of geographic information has its own characteristics.Based on 1:4000000 global geographic information processing,this paper has a research on the key technologies of cartographic generalization with the full analyzing of the characteristics of the small scale geographic information data.The main research content is as follows:1.The paper analyzes the features of 1:4000000 global geographic information production from the use of the digital map and map contents,points out the graphic characteristics of geographic information in small scale map.The research clearly gives the objects of cartographic generalization,provides directions and guidelines of the geographical elements.The paper studies data integration processing: unifying data projection method to achieve seamless splicing;unifying the data formats and the coding systems of elements to make multi-source data integrate to a platform.2.The paper establishes a global grid model of geographic feature of areas.On the basis of analyzing the features of the existing grid model,this paper proposes a global grid model based on latitude and longitude,and sets up the global grid of geographic feature,which simplifies the complexity of cartographic generalization.Based on analyzed the influence factors of geographical elements selection,the paper determines the evaluation indexes of importance of the elements and the importance evaluation function of the elements,establishes the importance evaluation system of geographical elements.3.With the analysis of the composition and implementation process of selection rules,the selection rules are built,and according to 1:4000000 global geographic information production,the selection rules are classified and organized.The paper establishes selection models of settle places and rivers by three steps.Firstly the paper analyzes the graphic features of geographical elements and determines the priority of the elements.Then the paper uses analytic hierarchy process to consider the importance of both geographical elements itself and spatial distribution between elements.Finally the paper establishes models by expressing the selection knowledge formally by production rules and so the elements can be automatically selected.4.The paper analyzes the space conflict types of geographical elements in the really production,and studies the process to solve the space conflict between points and points,points and lines,lines and lines.By using buffer generation algorithm,the collision detection was carried out on the first and second conflict types.Then the paper analyzes conflict processing principle of the elements and gives the automatic process solutions.Considering the width of symbols and the minimum distance in map,the central line of line elements has translation process.Then the algorithm of BMN is used to detect the conflict of line elements and the conflict process of line elements is given.5.The paper establishes an experiment system with the models and the methods which are put forward in the paper.And also the basic condition and the main function of the experiment system are introduced.