基于三方向搜索的DEM中洼地处理方法
Depression removal method for grid DEM based on three-direction search
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摘要: 数字高程模型(DEM)是流域参数提取的基础,然而DEM中普遍存在的洼地和平地影响了流域水系的自动提取,因此洼地去除方法成为研究的热点。针对现有洼地去处方法存在的问题,提出了一种基于"三方向搜索"的洼地处理方法。该方法通过对洼地及其周围网格高程值增减来达到去除洼地的目的,避免了传统填洼方法大规模的对DEM进行增高处理。实验结果表明,该算法简单易行,能有效的去除洼地,消除DEM提取的河网中的伪河道及"平行线"现象;且对DEM中高程值的改动较小,从而较大限度的保留了原始地形信息。Abstract: The Digital Elevation Model(DEM)is the fundamental data source to extract the watershed parameters. However, the depressions and flat areas commonly exist due to the errors in the production of DEM. Various methods are thus proposed to remove the depressions and flat area in DEM. Most of the methods assume that the depressions are caused mainly by the underestimation of DEM values. In fact,the overestimation can also cause the depressions in the nearby grid cells. In this paper, a new method based on three-direction search is presented to handle the problems by both raising and reducing the DEM values. The result suggests that the proposed method is easy to implement and can eliminate the "parallel river" in the result,and makes less modification of the original DEM values only to keep the original information to the largest extent.