Analysis of Scale Effect Characteristics of DEM and Slope in Hilly Areas

Abstract

In order to reveal the scale effect characteristics of DEM and slope grid with different size in hilly areas, the paper uses the typical hilly areas in Chuanshan County in Suining City as the pilot-area. Multi-scale DEM and slope with the resolution of 1m, 2.5m, 5m, 10m, 15m, 20m, 25m and 30m are generated by using contours, elevations, rivers and other data from 1:10000 scale maps. The qualitative scale effect of elevation and slope is revealed by comparing the frequency distribution of multi-scale elevation and slope. The concept of standard frequency error for testing the loss or error of accuracy created by scaling is proposed here. The correlation between altitude error(y) and scale(x) is positively significant at 0.01 confidence level, and its coefficient is0.863. The model: y=-0.0004x2+0.0058x-0.0042 can be used to significantly describe the quantitative scale effect of altitude at 0.01 confidence level. The correlation between slope error(y) and scale(x) is positively significant at 0.01 confidence level, and its coefficient is 0.855. The model: y=-0.0001x2+0.0032x-0.0025 can be used to significantly describe the quantitative scale effect of slope at 0.01 confidence level. The research has important implication for selecting the optimal scale in specified terrain analysis of hilly areas.