干热河谷冲沟DEM插值误差的空间分布研究

Study on Spatial Distribution of DEM Interpolation Errors in the Gully of Dry-Hot Valley

  • 摘要: 为了分析云南元谋干热河谷典型冲沟插值误差的空间分布特征,采用反距离加权(inverse distance weighting,IDW)、局部多项式(local polynomial interpolation,LPI)、张力样条(spline with tension,ST)、析取克里格(disjunctive Kriging,DK)以及不规则三角网(triangulated irregular network,TIN)模型方法对高程采样点进行插值,用交叉验证法、相对差系数及沟谷线差异衡量其插值精度。遴选高程误差大于1 m的误差点,用变异系数(coefficient of variation,CV)、全局Moran指数和Getis-Ord Gi*指数分析其空间格局特征。结果表明:TIN和DK精度较高,IDW精度最低;高程误差均呈聚集分布,聚集程度TIN > LPI > DK > ST > IDW;高程误差均呈空间正自相关,TIN模型插值误差的自相关程度最高;误差热点位于坡度大的区域。

     

    Abstract: To analyze the interpolation errors spatial distribution characteristics of the typical gully of Yuanmou dry-hot valley, the measured elevation points were interpolated by inverse distance weighting (IDW), local polynomial interpolation (LPI), spline with tension (ST), disjunctive Kriging (DK) and triangulated irregular network (TIN)model to generate DEM. Cross validation, relative difference coefficient and the valley lines discrepancy were used to evaluate the interpolation accuracy. The error points with elevation error greater than 1 m were extracted, and their spatial distribution characteristics were analyzed by coefficient of variation(CV), global Moran's index and Getis-Ord Gi* index. The results show that DK and TIN model had higher interpolation accuracy, the height error points of five interpolation methods were overall aggregating distribution, and the degree was TIN > LPI > DK > ST > IDW. Height errors were significantly positive spatial autocorrelation and TIN model had the highest autocorrelation degree, the hot spots of errors were distributed in the area with large slope.

     

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