Global DEM Accuracy Evaluation Method Based On Glas Laser Altimetry Data

With the construction of global geographic information resources in countries around the world,the global DEM is also becoming extensively used in various industries.And during the process of application,the accuracy evaluation of DEM is of great significance.Currently,the global DEM data products in China mainly come from domestic stereo mapping satellite ZY-3 image data,whose accuracy verification is made mainly on the basis of ground control points and third-party data evaluation.While for existing methods,there are obvious defects in the data availability,efficiency and reliability.Therefore,this paper proposes a method of referring to GLAS laser altimetry data to evaluate the accuracy of ZY-3 global DEM.After systematically summarizing the overview of global geographic information resources construction,the basic provisions of DEM accuracy evaluation,related indicators,and existing technologies and methods,this paper designs a DEM accuracy evaluation method based on GLAS laser altimetry data.It selects ZY-3 global DEM data of three different types of terrain areas of the Thailand-Laos border,Henan province in China,Bangladesh,and adopts the method of evaluating DEM accuracy with corresponding ICESat / GLAS laser altimetry data.The main aspects are as follows:(1)For the problems of inconsistent modalities and sampling densities of ICESat /GLAS laser altimetry data and ZY-3 global DEM data,this paper normalizes them according to their characteristics,and proposes a moving average method for DEM data with laser spot data as a reference.(2)Through the method of vectorizing the target area by establishing buffers,mask extraction,and grid turning points,and the way of performing GLAS strip traversal to construct a sliding window least squares search by considering the changing trends of the distance,direction and elevation into consideration,it can correct the plane offset of GLAS data relative to ZY-3 DEM data,which lays a solid foundation for subsequent accuracy evaluation.(3)By matching the strip comparison chart,the trend of section line-elevation point,and statistics of elevation difference distribution with the three accuracy evaluation indicators of mean error(Mean),standard deviation(STD),and root mean square error(RMSE),it helps to carry out reliable accuracy evaluations on the three selected test areas from both qualitative and quantitative perspectives.(4)With C # as the development language,sliding window least squares search of GLAS laser altimetry data and ZY-3 global DEM data as the method,it makes the automated,versatile and extensible ZY-3 global DEM data accuracy evaluation tool a reality.According to experiments,the ZY-3 DEM accuracy evaluation method based on GLAS laser altimetry data in this paper possesses stronger versatility,better suitability and higher efficiency than the existing global DEM accuracy evaluation method,which provides certain theoretical support for the practical application of ZY-3 global DEM in China.At the same time,the ZY-3 global DEM accuracy evaluation tool developed in this paper also has practical application value for production units.