利用局部Morans I指数进行DEM地形简化
Terrain Simplification from Grid DEMs Based on Local Moran’s I Index
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摘要: 地形简化是构建多尺度DEM数据库的重要技术。基于DEM地形数据空间自相关特征,提出了一种利用Moran’s I指数的DEM简化方案,即在计算DEM格网单元局部Moran’s I指数的基础上,通过设定阈值提取候选地形特征点,进而重构结果DEM。以黄土丘陵沟壑区为实验样区,将重要点法作为对比算法,从候选特征点分布、高程统计参数、地形结构特征等方面,对该方法的地形简化效果进行了分析。实验结果表明,基于地形空间自相关特征的DEM地形简化方法原理明确,技术方案易于实现,执行效率高,相对于重要点VIP地形简化算法,重构DEM能较好地保持地形的结构特征。Abstract: Terrain simplification algorithms from grid DEMs of high resolution offer an effective solution for constructing multi-scale DEMs. This paper presents a simple method for simplifying terrain from dense grid DEMs based on a grid cell’s spatial autocorrelation. A simplified DEMs is reconstructed by calculating local Moran’s I index for DEM cells with terrain feature points obtained with an appropriate Moran’s I threshold value. The effect of reconstructed DEMs was evaluated for a test site in an area in loess hilly-gully region with 5 m DEMs.The values for elevation statistical parameters，the structure of terrain feature lines and slope values are aquired from the DEMs reconstructed by the local Moran’s I index and very important points(VIP) algorithm.Experiment results with a comparison to the VIP method show that the proposed algorithm is clear easy procedure，and highly efficient;it delivers near-perfect precision retaining the geo-morphological skeleton by analyzing spatial distribution of surface-specific structural points used to reconstruct new DEMs.
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