DEM不确定性影响评价中的填洼分析

Effect of Sink Filling on DEM Uncertainty Evaluation

洼地广泛存在于DEM实现中,洼地的处理会影响DEM不确定性评价结果。该文利用蒙特卡罗方法模拟DEM不确定性,用偏差指标评价DEM不确定性对坡度和地形指数的影响,将填洼与不填洼情况下的偏差指标相减来量化填洼对DEM不确定性评价的影响。研究发现,洼地对不同参数DEM不确定性影响评价作用不同,随着DEM不确定性的增大,洼地的影响也增大。

Sinks are very comrnon in DEM realizations produced in DEM uncertainty evaluation,which is affected by sink filling. This paper aims to analyze quantitatively the impact of sink filling on DEM uncertainty evaluation. Slope and the topographic index were chose as research objects,and the bias index was used to evaluate the effect of DEM uncertainty on the selected topographic parameters. The investigation was carried out as followings. Firstly, the disturb values were produced according the assumptive Root Mean Square Error （RMSE） value based on the Monte Carlo simulation. The disturbed values were then added to original DEM to create the DEM realization. Secondly, the bias indexes of slope and the topographic index were computed based on filled and unfilled DEM realizations. Finally, the effect of sink filling on DEM uncertainty was quantified by comparing the mean bias indexes on filled and unfilled DEM realization conditions. The result shows that the sink filling effect on DEM uncertainty evaluation of different topographic parameters is different,and it is increased with the bigger DEM uncertainty.