反距离加权插值算法中插值参数对DEM插值误差的影响

插值算法是影响DEM精度的主要因素之一,对于插值参数如何影响插值算法并最终影响插值精度却研究较少。这里以反距离加权插值算法中的插值参数为实验对象,选取了6种不同地貌类型的离散点数据,基于中误差度量指标,运用交叉验证方法研究权指数、搜索点数、搜索方向对DEM插值精度的影响。实验结果表明:1)在搜索方向方面,四方向搜索和八方向搜索对提高DEM插值精度并不明显;2)搜索点数为8～12点是较好的选择;3)当权指数≥3时,对DEM插值精度的影响不明显,2或3是较好的选择;4)3因素对DEM插值精度的显著性影响顺序为"权指数>搜索点数>搜索方向"。

Effects of Interpolation Parameters in Inverse Distance Weighted Method on DEM Accuracy

Interpolation method is one of the most important factors which influence on the accuracy of DEM.However,there are few researches on how interpolation parameters influence interpolation method as well as the interpolation accuracy at last.The interpolation parameters of distance weighted interpolation method was considered as the research object,and respectively selected 6 kinds discrete data as the original data.Then metrics of RMSE was used to measure RMSE of the generated DEM in order to study that how interpolation parameters,including weighted index,search points,search directions,search radius in distance weighted interpolation method affected the accuracy of DEM interpolation.It was drawn: firstly,in the aspect of search directions,it was not obvious to use the four-direction and eight-direction to improve the accuracy of DEM interpolation;secondly,the best search points were 8~12 points;thirdly,when the weighted index was higher than 3,the impact of the change in weighted index on DEM accuracy tended to be not obvious,the best weighted index should be 2 or 3;finally,the degree of influence on the accuracy of DEM interpolation was "the power index>the search points>the search direction".