The Results Of Analysis And Quality Control Of Construction Of DEM Process By DLG Data

Digital elevation model(DEM)as a collection of surface information is an important part of GIS spatial database of geographic information system.And in the engineering foundation construction,digital city,military simulation and other terrain analysis,DEM is one of the most important basic data.Therefore,the large-scale construction of high quality digital elevation model has become a hot issue in the current research.At present,the methods of constructing DEM mainly include field measurement,aerial photogrammetry,synthetic aperture radar interferometry,and the existing topographic map digitization.Although with the rapid development of Surveying and mapping technology,build high precision DEM emerge in an endless stream,however,in meet the accuracy requirements,from the engineering actual operation,cost,efficiency factors considered,the existing topographic maps of various scales of digitally generated DEM is still one of the most important methods.This paper starts from the definition of digital elevation model(DEM),comparative analysis using a variety of data sources construction of the advantages and disadvantages of the methods of DEM,and draws a conclusion that the DLG Data Source Method to construct DEM is applied in current production practice is one of the most widely used method.In order to better ensure the production practice project get the accuracy of DEM,this paper systematically describes the theory and method of constructing DEM,details of the digital elevation model(DEM)sampling theory and contrastive analysis of the mathematical model of DEM Interpolation,so as to provide a theoretical basis for quality assessment of digital elevation model(DEM).And focus on the production of high quality DLG data based on DEM.In this paper,Zhangjiajie City,Hunan Province construction project of the production practice in DEM Based on DLG Data,and puts forward the following measures to ensure the DEM accuracy: Based on the secondary development of Auto CAD software GEOONE of DLG Data Source for data check to reduce the error of original data.Design a set of automatic extraction algorithm of feature points in order to build out to take into account information on terrain features of tin;tin in the regular grid DEM.Finally,using the relevant knowledge of the experimental data and mathematical statistics,the quality evaluation of DEM was performed by using the method of inspection points and contour line playback.From the experimental data can be introduced in this paper,the quality of the content and method can control the quality of DEM results,improve the inspection efficiency and operational.Thereforethis paper uses the semi-automatic half manual production high precision DEM the way is has the practical significance.