Research On DEM Fusion Method Based On SRTM3 DEM And ASTER GDEM

This paper uses data fusion technology to achieve the fusion of SRTM and ASTER DEM, making DEM further improve the horizontal resolution and elevation data accuracy. The research is divided into two parts: Firstly, the integration of DEM resolution, namely that the best grid size calculation on fusion of DEM; Secondly, the fusion of DEM elevation, namely that the compution of fused DEM elevation. The main contents are as follows:(1) The best grid size calculation on fusion of DEM. This research based on the platform of Arc GIS, SRTM and ASTER DEM are converted into discrete points and superimposed, generating different size of DEM grid. And we introduce the conception of information entropy, the terrain information(terrain factor) is extracted in different DEM.To determine the best size og DEM grid, we program by Mat Lab to calculate information entropy according to the calculation formula,and analyse the relationship between terrain information entropy and DEM grid size to find out the point when the terrain information entropy tends to be stable.The experiment showed that the fused DEM grid size from 90 MSRTM DEM and30 ASTER DEM fusing optimal applied to the experimental area is 40 m by extracting the information of slope, slope direction, section curvature and curvature of the DEMs.(2)The calculation of the fused DEM elevation data. This study bases on the flowing simulation method, the extraction of valley and ridge lines from SRTM DEM and ASTER DEM is achieved. From the perspective of integration, Multiimage feature extraction method is used in this paper to fuse the of valley and ridge lines from SRTM DEM and ASTER DEM. After the fusion, the valley and ridge lines will be the interpolation constraints, and then it will be inserted for each DEM to achieve the fused DEM with best grid size. Then, we improve the traditional weight gaining method, the performance index of RMSE is optimized through ergodic process of weight, by this method, the fused DEM is produced.Finally, we assume 1:10,000 as the true value of the experimental area and analyze the DEM accuracy by evaluating checkpoints and contour-matching methods. The experiments show that: although the the resolution of the fused DEM is relative higher than SRTM DEM and lower than ASTER DEM, the accuracy of the source data are improved than both of them,and the terrain contour matching is better that can be better reflect the form and its change. The fusion technology achieve the complementary of SRTM and ASTER DEM advantages,provides a feasible technical scheme for application of multi DEM to generate better accuracy,higher reliability of DEM products.