The Study Of Auto Generalization Algorithm And Application For Spatial Objects Based On Least Squares Adjustment

The study of Automated Generalization algorithm for spatial objects is a key problem in the field of GIS, and it's also a hot point in cartography.In this paper, I haved studied the multi-scale automated generalization algorithm for buildings in the city, with reviewing and analyzing the progresses of the generalization algorithm over the world.Firstly, I systematically analyze the characteristic and problems, which exist in the three stages of map generalization: man-maded cartographic generalization, digital artographic generalization, and automated generalization for spatial objects in GIS.I apply the least squares adjustment to map generalization, and bring forward generalization model based on least squares adjustment aimed at the questions,Secondly, I systematically studythe process of the automated generalization for spatial objects , I point out two key problems in the model, one is the detecting shape of spatial objects, and the other is the set-up of the constraints by analysing of the process of modeling. In view of the characteristic of the buildings in the city, I offer two methods for shape detecting: tracking and cutting, and then contrastively analyze them; I also offer some applicable constraints according to the geometrical characteristic of urban buildings, such as the minimum visible length or area, the characteristic of objects, the constraint for reposition, and so on.Generalization assessment is a key aspect in the application of the result of generalization, Furtherly, I set up a set of indexs system ,and offer the way of calculating them.based on them ,1 set up two assessment way:indexes assessing and fuzzy assessment, and carry out the assessment for the result of generalization.Finally, the software modules of automated generalization for spatial objects have been empoldered using MapX under the circumstance of visual basic6.0, including simplifying a building, and simplifying, merging, displacing building group. At the same time, each module is verified with several examples.