Three-dimensional Expansion Model Of Contour Tree And The Application In The Analysis Of Geomorphologic

The surface of the earth is composed of various topographical features and undulating topography.It may seem as if there is no law on the surface.However,it contains abundant geographical information and is closely related to people's production and life.The analysis of geomorphologic is an important foothold for human to understand and transform nature.With the development of computer technology,GIS(Geographic Information System)plays an important role in the analysis of geomorphologic.The large and cumbersome geospatial data can be effectively organized and managed with its help.Also,accurate and quantitative analysis of geomorphologic could be provided by it.As an important role in GIS,DEM(Digital Elevation Model)is the main means for quantitatively and automatically expressing the topography.As for the three common types of DEM—Grid(regular grid),Tin(irregular triangulation)and contour—play different roles in ananlysis of geomorphologic.Due to the simple data structure,Grid and Tin could be easily processed by computer.Terrain indices,for example,slope and aspect could be easily extract by them.Thus,they are now highly used in geomorphological analysis.Contour lines are ofter used as data source for the other two types of data.From the theoretical perspective of the data conceptual model,DEM is the field model.It is pointed out by some scholars that the analysis of geomorphologic based on the field model would run some errors.The discrete data of DEM should be converted to solid objects.Under this view,contour lines are significantly superior to the other two.That could be see when someone read contour maps.People could easily find some real geo-object from contour maps,such as ridges,valleys and depressions.However,the contour lines are now rarely applied to the analysis of geomorphological.The main reason is that the contour data structure is complex and it is difficult for computer to recognize the special information contained in it.In order to satisfy the need of analysis of geomorphologic,this paper proposes a three-dimensional extension model of contour tree.What's more,some analysis would be provided based on the information extracted from the model.The traditional contour analysis process uses the contour tree model to construct the topological relationship between contour lines in a two-dimensional plane.In this paper,the three-dimensional extension model of contour tree is proposed to build the topological relationship,azimuth relation and measurement relationship among contour lines in true three-dimensional space,which would make the morphological features of the model have a certain geographical significance.Around the three-dimensional extension model of contour trees,the main contents of this paper are:1.Research on the knowledge system of the model.Base on the topological relationship,azimuth relations,and metric relationships of contour lines in threedimensional space,the knowledge structure system of the model is made.The concept,construction method and basic elements of the model are defined and explanation.2.Research on the index of the model.Following the principle of scientific,systematic,and accurate index selection,the indicators were extracted from the new model,and the quantitative formulas of indicators were clearly defined.3.The geomorphological character extraction method research based on the new model.Using the three-dimensional extension model of contour tree,the landforms are divided into independent units,the morphological characteristics of the contours are matched with the morphological indicators of the contour trees.Based on these them,the geomorphological characteristics of the interior and exterior of the geographic object are studied.4.Geomorphological analysis experiments based on the model.The Lushan region was used as an experimental area to construct a three-dimensional extension model of contour trees.Based on the above theoretical research,the three-dimensional extension model of contour tree are used to extract and analyze the topographical features of Lushan Mountain.Through the above research,the theoretical framework of the three-dimensional extension model of the contour tree is established.The practice has proved that the contour line tree three-dimensional expansion model can extract the topographical morphological features contained in the contour lines in an object-oriented manner.At the same time,through the extraction and analysis of the morphological information of Lushan geomorphology,the applicability of the three-dimensional extension model of contour tree in geomorphological analysis is proved.