| 正六边形规则格网表达的DEM谷地线提取 |
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| 引用本文： | 王璐,艾廷华.正六边形规则格网表达的DEM谷地线提取[J].测绘学报,2019,48(6):780-790. |
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| 作者姓名： | 王璐 艾廷华 |
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| 作者单位： | 武汉大学资源与环境科学学院,湖北武汉,430079;武汉大学资源与环境科学学院,湖北武汉,430079 |
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| 基金项目： | 国家自然基金（41531180）；国家重点研发计划（2017YFB0503500） |
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| 摘 要： | 基于规则格网DEM谷地线提取受格网的几何形态、空间剖分和网格布局影响较大.传统的四边形格网D8 算法中,四边形网格的角邻域与边邻域存在的距离度量差异,影响了其计算结果对于地形变化的表达在两方向上的均衡性,从而影响了谷地线提取结果.六边形格网具有邻域一致、各向同性、紧凑、采样率高等优点,在空间场建模中越来越得到重用.本文旨在探求六边形格网结构在DEM谷地线提取中的性能特征,发现其与四边形格网比较的突出优势.基于六邻域处理单元,对六边形格网DEM谷地线提取过程中填洼、流向计算及平地区域流向判定作预处理,然后对流向线作拓扑连通组织,从而实现基于六边形DEM的谷地线提取.本文比较发现六边形方法在谷地线形状特征保持方面能力强,随着分辨率减小,六边形DEM所提取的谷地线与实测数据吻合程度高,弯曲特征继承性强.同时,在相同数据存储量条件下,六边形DEM数据精度更高,且其提取的谷地线网络的形状特征更为精细.
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| 关 键 词： | 六边形格网 DEM分析 D6算法 谷地线提取 |
| 收稿时间： | 2018-09-05 |
| 修稿时间： | 2019-03-25 |
The valley extraction based on the hexagonal grid-based DEM |
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| WANG Lu,AI Tinghua.The valley extraction based on the hexagonal grid-based DEM[J].Acta Geodaetica et Cartographica Sinica,2019,48(6):780-790. |
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| Authors: | WANG Lu AI Tinghua |
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| Institution: | School of Resource and Environmental Sciences, Wuhan University, Wuhan 430079, China |
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| Abstract: | Valley extraction from grid-based DEM depends on the geometrical shape, spatial tessellation and placement of grids. Traditional researches ignore that the shape of grid can influence the neighborhood relationship, impacting on the result of valley extraction. The traditional D8 algorithm is based on eight-neighborhood relationship, where the distance difference between node neighborhoods and edge neighborhoods results in the imbalance of topographic change expression in these two directions and further affects the extraction results of the valley lines. Hexagonal grid has been proved to be advantageous over square grid due to its consistent connectivity, isotropy of local neighborhoods, higher symmetry, more compact, and so on. Taking these merits into consideration, this paper tries to explore the advantage of hexagonal grid-based DEM on the results of valley extraction in comparison with traditional square structure. First, preprocess for valley extraction with depression filling, flow direction calculation and the flow direction in flat area based on the six-neighborhood relationship. Then, connect the flow lines according to the estimated flow direction. From the comparison between the results of hexagonal grid-based DEM and square grid-based DEM, we conclude that the hexagonal grid-based DEM has a superior capability in maintaining the detailed shape and the characteristics of extracted valley networks. That is to say, with the decrease of resolution, the valley lines extracted by hexagonal DEM have better spatial agreement with real river systems, and the shape loss characteristic of them is lower. In conclusion, the hexagonal grid-based DEM has higher data accuracy, and it can extract a finer valley networks with same data volume. |
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| Keywords: | Hexagonal grids DEM analysis D6 algorithm valley extraction |
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