DEM Scaling Up Based On Algebraic Multigrid Method And Most Suitable Resolution Determination

Scale and scale conversion are the key issues in DEM terrain analysis.DEM terrain analysis has a large degree of scale dependence.According to the content of research objects,should selected corresponding scales DEM data.Therefore,Scale and scale conversion have always been the key points in Geo-science research.this paper is divided into two parts: The first is the DEM scaling up based on algebraic multigrid method,and evaluates experimental results from three aspects: data accuracy,shape retention,and spatial autocorrelation;The second is use the method based on information entropy to determine the most suitable resolution for the experimental results.The first is based on the algebraic multigrid method of DEM scaling up.The algebraic multigrid method is mainly divided into two parts: the smoothing process and the correction process.The smoothing process refers to the removal of high-frequency components in the data.The correction refers to helping to correct the smoothed low-frequency components.The DEM data can be viewed as a two-dimensional image,AMG method can retain basic skeleton information such as terrain feature lines and retain the details.This idea is consistent with DEM scaling up.In this research,DEM data with30 m resolution and size of(1001,1001)in SRTM DEM is selected as the experimental source data.After the source data is preprocessed,algebraic multigrid method is used to iteratively calculate the data.According to the basic principle of DEM scaling up,Selecting the checkpoint method,the valley ridge fitting method and the Moran index to evaluate the quality of the experimental results in terms of morphology,data accuracy and spatial autocorrelation.The experimental results show that the results of the DEM scale-up results based on the algebraic multigrid method are better in the three aspects of data accuracy,overall data morphology and spatial autocorrelation.The experimental results show that the scaling-up result of DEM based on algebraic multigrid method is reasonable.The second is use the method based on information entropy to determine the mostsuitable resolution for the experimental results.The results of the DEM scaling up experiments based on algebraic multigrid method must further determine the most suitable resolution.Firstly,Build different resolution DEMs.Extract terrain factors at different resolution DEMs and calculate information entropy.Draw information entropy and resolution polyline diagram.According to the relationship between information entropy and DEM resolution size,find the definite points where information entropy tends to be stable,and then determine the most suitable resolution of the experimental results.Experimental results show that the most suitable resolution of DEM for the first and second iterations of the algebraic multigrid method is 80 m and 160 m.