基于分数进制小波变换的分辨率可指定的DEM综合方法

DEM的尺度效应研究需要分辨率连续变化的,空间定位基础一致的DEM数据作为数据源.针对这种需求,本文基于采样定理与分数进制小波变换,探讨了一种由较高分辨率DEM生成较低分辨率DEM的有效综合方法.首先基于采样定理分析了DEM分辨率与最高频率的关系,提出了通过降低DEM有效最高频率获得分辨率指定的DEM的新思路;然后基于该思路,探讨了分数进制小波变换自由精细的时频分解性能,以及对各分解部分的基于能量的阈值处理过程,进而实现了一种分辨率可指定的DEM综合方法;最后,对所指定的分辨率的合理性、空间定位的一致性、所生成DEM的综合效果进行了实验论证,并将所得DEM与由地形图派生的DEM以及由常规方法所得的DEM进行了对比分析,结果验证了该方法的有效性.

Resolution-assignable DEM Generalization Based on Rational-dilation Wavelet Transform

A DEM generalization method to obtain lower-resolution DEM based on higher-resolution DEM was proposed by applying sampling theory and rational-dilation wavelet transform(RWT),as scale impact researches require the DEM dataset possessing continuously changeable resolutions and uniformly spatial location base.The relation between DEM resolution and sampling theory was analyzed and a new way to obtain resolution-assignable DEM by reducing the efficient max frequency in frequency-domain was presented.The freely and finely time-frequency decomposition via RWT was studied,and the energy-based threshold processing to the decomposed parts was proposed.A generalization method to generate resolution-assignable DEM was then obtained.The assigned resolution’s validity,the spatial location consistency and the generalized effectiveness were proved,and the generalized result’s advantage over the interpolated DEM from topographic map and the DEM from conventional methods were analyzed,via experiments.The result shows the method’s effectiveness.