Map Layered Vector Research And Realization

For many years, research and development of GIS home and abroad show that data entry is the biggest "bottleneck" in application and development of GIS. That is to say, there is no a absolutely effective method that can recognize automatically every ingredient of paper map and digitize it. Special focus is given to the dedicated systems for the applications of certain aspect. In this paper, the subject is researched and discussed.The paper begins with the history and present condition of research and application of GIS. Then 3D GIS and its construct is introduces briefly, and the relevant background and theory are studied, such as picture segmentation, pattern recognition and vectorization technology, etc.It is discussed in detail how to realize the data entry of contour lines(include extraction, pretreatment, vectorization and making DEM) in 3D GIS by using computer graphics, image processing and visualization programming technology, and a complete set of concrete scheme to design a system recognizing automatically contour lines from scanned data of map is put forward. In this scheme, HSV model & threshold segmentation method is used for contour line extraction, and the method combining automatic trace and manually trace is used for vectorization. Finally, we use component interpolation to make DEM data. All algorithms are realized in terrain modeling and synthetically analysis software developed by VC, OpenGL and Oracle. This software is characterized by fastness and friend interface, and is a data entry platform of contour lines in map that can fill need of practical applications verified by theoretical analysis and practical use.