A Precision Evaluating Method of DEM Using Map Spots Generated by Contour Superposition

摘要

Aiming at the shortcomings of traditional contour superposition analysis in quantitative evaluation of DEM error, the purpose of this paper is to propose a new method to measure the DEM accuracy by using the map spots of contour superposition. To begin with, the concepts of the difference rate and the matching rate for contour overlaying was described, and the calculating methods about the two indices were illustrated in accordance with the map spots generated by contour overlaying. Then, this paper comparatively illustrated the consistency between the terrain coincidence reflected by the matching rate of the same name contour lines and the mean elevation difference of the reconstructed DEM and the original DEM. Finally, this paper analyzed the influence of contour interval to the difference rate of the contour superposition. Meanwhile, taking slope as the complexity factor of terrain and selecting different experimental areas with different average slope, the correlation between the difference rate of contour superposition and the average slope of experimental area was quantitatively measured by regression analysis method. The experimental results show that map spots generated by contour superposition can be used to reflect the terrain coincidence between reconstructed DEM and original DEM, and the matching rate of contours is positively correlated with the total number of the map spots, but negatively correlated with the relevant indexes of the area of the map spots. The method proposed in this paper not only can reflect the statistical characteristics of DEM error, but also can describe the spatial distribution of error.