DEM地形简化指标的分析研究

该文对基于局部误差、曲率和法向量的5个地形简化指标进行分析评价，用离散的高斯合成曲面来模拟真实DEM，以解析得到的高斯曲率作为地形简化指标“真值”，通过对各个指标“保特征性”可信度的分析，获得对这5个指标的整体评价：1)基于法向量的地形简化指标更能反映地形特征；2)各指标的“保特征性”随简化比的减小呈线性上升；3)各指标的优劣排序对地表形状和分辨率不敏感；4)各指标“保特征性”可信度在同一分辨率下较为稳定。并用实例验证结论的正确性。

Comparison of Terrain Simplification Indices Based on Grid DEM

Terrain simplification algorithms are widely applied to digital elevation model as important technology of compressive data.How well the effect will be acquired depends upon terrain simplification index,which is one of the core parts among these algorithms.This paper analyzes five indices,which are based on local error,curvature and normal vector and estimates their capability of preserving terrain characteristic.Firstly,the authors construct gauss mesh which is used to simulate real terrain by gauss curved surface and calculate total gauss curvature of each grid point,which is regarded as true value to terrain simplification index.Secondly,reliabilities to preserve terrain characteristics are obtained by comparing these indices with gauss curvature.Macro-estimate of the five terrain simplification indices are gained by analysing their reliabilities and so do when changing gauss mesh's shape and resolution.The macro-estimation includes:1)as to the potential of reflecting terrain characteristic,the index based on normal vector is better than the others;2)their reliabilities linearly ascend as terrain simplification ratio reduces;3)their sorts are liable to terrain and resolution;4)their reliabilities are steady at the same resolution.Finally,the authors testify research result based on a lot of real terrain and find that it is all right.