Study Of DEM Generation And Uncertainty

This thesis firstly gave a review and assessment on literature, and pointed out the limitations. Based on these limitations, this thesis started from theoretical lack of interpolation method, deduced a new theory of DEM generation that satisfied geometric structure on the surface, and studied the precision in experiment. This thesis investigated the propagation error of DEM, and investigated proportion between propagation error and terrain error in the global error of Digital Elevation Model, and settled the problem that the appropriate interpolation method is selected, and studied the spatial character of DEM's error.The major contributions are as the following:1. The Construction of The Coons Digital Elevation ModelThis thesis proposes a new theory of DEM generation and constructs the Coons DEM model based on the approximation of topographical profile curve corresponding to the grid boundary curve interpolated by some adjoining grid points. For the constructing method, the model will change according to the topographical profile curve's change. As shown in experiment the Coons DEM model has high precision, its terrain simulation error is better than other DEM models'constructed with bilinear interpolation and moving surface fitting, and it reduces the terrain simulation error 15%—28% comparing with bilinear interpolation DEM model.2. The Propagation Error of Digital Elevation ModelThis thesis investigated the propagation error of Digital Elevation Models. The propagation error of grid DEM has connection with grid points'quantities, the more grid points the model of grid DEM is based on, the bigger the propagation error of the DEM model based on same interpolation is.3. The Global Error Model of DEMThis thesis studied the global error of Digital Elevation Models based on the data appended stochastic errors obeyed normal school of mathematical surfaces. As shown in experiment the precision of Digital Elevation Model not only relates to sampling interval and terrain complexity but also relates to interpolation method and original data error. This is supplement that the precision of Digital Elevation Model lies on sampling interval and terrain complexity. 4. Terrain Adaptation of Digital Elevation ModelThe thesis studied that the terrain adaptation of Digital Elevation Models. The thesis presented the way to select appropriate interpolation method. People can select the appropriate Digital Elevation Model because of the study of the terrain adaptation of Digital Elevation Model.5. The Model of DEM's Global Error Based on Spatial AutocorrelationBased on Digital Elevation Model error model, this thesis testified that Digital Elevation Model error existed spatial correlation, and indicated spatial character of Digital Elevation Model error. The result obtained provides an important theoretical basic for simulation. The result provides an impersonal gist for estimation at practical work too.The thesis proposes a new idea of DEM generation that constructs the Coons DEM model, it perfect methods of existing Digital Elevation Models. The model of terrain adaptation of Digital Elevation Model provides a way to select appropriate interpolation method in different terrain and original data error. The models of DEM's global error and DEM's global error based on spatial autocorrelation provide more credible theoretical basic. The study provides a scientific gist for instituting sound quality standard of DEM.