DEM径向基插值搜索方式优选分析

Research on search parameters optimization for constructing DEM with radial basis functions interpolation

针对径向基函数插值算法中搜索参数优化选择问题,基于3种不同地形样区离散点数据,使用中误差度量指标,研究搜索点数与搜索方向对DEM插值精度的影响。实验结果表明:平原样区和丘陵样区适宜采用自然三次样条曲面函数和薄板样条曲面函数,搜索点数上下限值控制在10~21之间(自然三次样条曲面函数在平原样区上限值以18为佳),搜索方向对插值精度影响不显著;山地样区适宜采用多重二次曲面函数插值,搜索点数上下限值设置为16~21,应用四方向45°旋转搜索。该研究可消除径向基插值搜索方式参数选择的随意性,为不同地貌类型区DEM构建提供参考。

Aiming at discrete points collected from three geomorphic area, the influence of search points and directions on the interpolation accuracy of DEMs was investigated using Root Mean Square Error (RMSE) to select the parameters properly when constructing DEMs with radial basis functions. The results show that: for the plain and hill sites, Natural Cubic Splines Function (NCSF) and Thin Plate Splines Function (TPSF) are of higher accuracy with search points between 10 and 21 (the maximum being less than 18 for NCSF in plain area) and search directions have a little impact on the results. For the mountain site, multi quadric function (MQF) is the best choice with search points between 16 and 21 and orienting in four-directions 45° rotation. The research is helpful to optimizing the interpolation parameters and acquiring better output DEMs.