The Study On Patches Merging In Land Use Spatial Database Based On The Constrained Delaunay Triangular Irregular Network

Land use spatial database is a kind of geographic information database that built by government for effective management of land resources. It assists departments to plan and management the land resources in a reasonable way under the background of digital earth. Land use spatial database is based on the national land survey work and describes the present situation of land use, ownership, condition and plenty much details of the basic information of land and resources under the 1:10 thousands scale. However, in the huge amounts of information database, vary departments need different level of detail information in their application. To meet their needs, using cartographic generalization to produce a new database in different scale or different thematic based on original database in 1:10 thousands scale is crucial.A number of problems about polygons generalization in land use database were studied in this paper. The land use data is full coverage, not cracking and not overlapping in geometric, it also has abundant information in its attribute which makes it very different from graphic data. At this point, there are more constraints to follow in the process of land use data cartographic generalization, administrative boundaries is one of them. On the basis of the theory of cartographic generalization, we formulate rules of the land use database generalization according to the characteristics of the land use data. Analyzing the existing GIS software ArcGIS application in cartographic generalization, we find that its function is limited. Therefore, this paper built a Delaunay Triangular Irregular Network under the restriction of administrative boundaries to solve the problem in generalization, taking the advantage of the grid model based on space subdivision in cartographic generalization. Presenting a model to analyze the proximity between patches, then, and we generalize the small patches, narrow patches and island In identifying the nearest polygon premise. Finally, we discuss the way of patches docking in collapse dual lines to centerline in narrow patches generalization.