Research Of Isoline Generation Based On Grid Model

With the development of Geographic Information System (GIS), Digital Elevation Model (DEM) has become an important part of spatial information system, and one of the best important and basic data in these fields, such as constructing project and emulating battlefield environment.The isoline graph has been widely used in engineering and technique field, such as oil exploration development, mining, geology, physical geography, geochemistry and meteorology, and it is one of the important maps that the achievement of many fields show. It also unifies shape and data.The thesis mainly researches the following contents:algorithms of isoline generation and fill based on grid model.In the algorithm of isoline generation, the process of selecting and creating interval tree nodes is similar with the process of insert nodes in AVL tree, Interval tree's structure can be created by scaning all grids once.When searching the given altitude, we just sort those grids which are belonged to the nodes the search path passed, avoid sort all grids in the interval tree, reducing the search time。This thesis proposes an algorithm which can fill the isolines graph with random boundaries。When creating the location relationship between all isolines, this thesis utilizes the relationship between boundary of grid and isoline, use boundary of grid and isoline to create radials.By the theory of radial, we can get the location relationship between some isolines once time, and the algorithm is faster than the other algorithms.