Dem Grid Cell Heterogeneity In Multi-scale Terrain Analysis

Digital Elevation Model (DEM) is an approximate description of the surface configuration, which describes the directional distribution of landscape in certain region by discrete data. Digital Terrain Analysis (DTA) is a landform analysis method on the basis of Digital Elevation Model. With the widespread use of computer and digital technique, DTA has become the main method of acquiring the surface configuration parameter, which is on the basis of Digital Elevation Model,and the achievement has been widely used in hydrology, soil, environmental and many other fields. In Digital Terrain Analysis, the internal of the grid is believed to be homogeneous, and the real surface configuration of the area which it represents doesn't change. In fact, the terrain which is represented by grids is very intricate. And any ignoring the topographical changing might deviate the analysis results, then affecting the application of the results of the analysis, and bring loss to the practical work.Therefore, this paper taking the heterogeneity of DEM grids and its impact on the terrain analysis as the object of study, and taking the typical landform types in the Loess Plateau as example, describe the heterogeneity of DEM grids, and analysis the discipline of the influence that the heterogeneity of DEM grids causes to landform analysis. This paper use six different kinds of methods to quantify the heterogeneity of DEM grids on the basis of GIS, digital terrain analysis, landscape ecology and other disciplines. At the same time, this paper analysis the gradient extraction, curvature extraction, roughness of surface extraction and cleugh extraction reckoning without the heterogeneity of DEM grids and taking it into account, and study experimentally the discipline of the influence that the heterogeneity of DEM grids causes to landform analysis with the comparative analysising and mathematical statistics.Results shows that the heterogeneity of DEM grids would have affected the landform analysis, and make analysis results deviate from the practical situation. And the more complicated the landform is, the more deviation it makes. Therefore, the heterogeneity of DEM grids should be fully taken into consideration during the landform analysis by DEM terrain data. This paper provides experience in considering the influence that the heterogeneity of DEM grids causes in digital terrain analysis. The heterogeneity index of DEM grids extracted from this paper can be used to describe the heterogeneity of DEM grids, and it also has a certain significance to improving the accuracy of terrain analysis.