Automated Extraction Of The Characteristics Of Topography From Grid DEM

Automated extraction of the topographic feature is a kind of geographic analysis methods, which extracts the earth surface features from DEM in GIS. It's not only widely used in geology, geography, agriculture, forestry, urban construction, regional planning and so on, but also significant to understand the knowledge of the earth surface.After comparing the research before widely, the dissertation analyzed the methods, system structure and data flow of automatic extraction approach based DEM, developed a program and tested it on data. It has drawn several conclusions below:(一) Summary on the basic theories and system structure of watershed basin analysis.Applying the globe approach and D8 algorithm, the dissertation presents the frame of watershed basin analysis and system structure of its model according the geomorphologic features, distributed hydrological models and data flow relationship.(二) The classification on DEM data shape and approaches for data conditioning procedures.Because DEM contains plentiful data shapes, the dissertation classified the data shape and discussed in details the reason and correlative relationship with real geomorphologic features of it.And then a new approach for data conditioning procedures is proposed, while discussing the research methods, asserting the implicit assumptions, arguing some problem currently, as well as presenting the solution of every section respectively.(三) Application of watershed basin analysis and its data test.The approach of watershed basin analysis is coded in a VC++ computer program, which solves several key problems, such as the design of the model function, the arrangement of data structure, the memory structure of 2D array, the search algorithm for array and so on. Then it's tested on data to automatic extract the drainage networks and watershed basin, whose results show that the approach solves the data conditioning procedures successfully and improves the computer efficiency.The conclusions of the dissertation proved that, the theories and techniques of watershed basin analysis and application are of theoretical significance and have a splendid perspective.