The Study On DEM Modeling Based On AutoCAD Advanced Development Technology

With the development of application of DEM on various fields,the DEM modeling technology's been studied by many scholars.An important application of DEM is on engineering project design field.This paper mainly studies the DEM modeling theories and methods basing on graphic design platform AutoCAD.First this paper introduces existing AutoCAD advanced developing technologies and the feature of ObjectARX technology,and the advantage of AutoCAD DEM modelling.Then,discusses the key algorithms and relevant key technologies of AutoCAD DEM modelling:1.The drawing of scattered points:discusses on the key algorithm and technology of drawing scattered points onto AutoCAD,and the goal of preprocessing of scattered points.The drawing of scattered points is the base of AutoCAD DEM modelling.The scattered points set is a simple point cloud DEM.2.The generating of DTIN:discusses on the features of DTIN and its advantages and disadvantages of terrain modelling.Compares the qualities of the main DTIN generating methods.And finally chooses the super triangle insert point by point method,and discusses its algorithm in detail.DTIN DEM is closest to the real terrain,so it has highest DEM precision.3.The generating of Grid Network:discusses on the difference between DTIN and Grid Network DEM and tne algorithm of generating Grid Network basing on DTIN insert point by point.And about the relationship of sampling desity of Grid Network DEM,the processing speed and the DEM precision.Grid Network DEM and DTIN are two common forms of DEM,DTIN to Grid Network is a transform of DEM display form.4.The smoothen of Grid Network:discusses the significance and the method of DEM smoothening.AutoCAD does not support Spline Surface,then uses Splines instead,generating smooth Splines DEM wireframe model.Then,three DEM application examples are given,usage of DEM on the area and volume statistics,3D visualization and engineering project aid design,and 3D virtual sight.They show AutoCAD DEM modeling is feasible,and advantages of the AutoCAD DEM modelling is powerful.Finally this paper analysises the advantages and some existing problems of AutoCAD DEM modelling.Then comes out with the resolve thinking and anticipate DEM modelling will develop alone the real time,high precision,full information,and large extent direction.