地球信息科学学报 ›› 2022, Vol. 24 ›› Issue (4): 643-656.doi: 10.12082/dqxxkx.2022.210405

• 地球信息科学理论与方法 • 上一篇    下一篇

正六边形格网DEM下的等高线生成算法及质量评价

肖坤(), 艾廷华*(), 王璐   

  1. 武汉大学 资源与环境科学学院,武汉 430072
  • 收稿日期:2021-07-17 修回日期:2021-08-13 出版日期:2022-04-25 发布日期:2022-06-25
  • 通讯作者: *艾廷华(1969— ),男,湖北宜昌人,博士,教授,主要从事空间数据挖掘,地图综合与尺度变换,可视分析。 E-mail: tinghuaai@whu.edu.cn
  • 作者简介:肖 坤(1996— ),男,河北沧州人,硕士生,主要从事地图综合、六边形DEM格网研究。E-mail: 2019202050048@whu.edu.cn
  • 基金资助:
    国家自然科学基金重点项目(41531180)

Contour Generation Algorithm and Quality Evaluation of Regular Hexagon Grid DEM

XIAO Kun(), AI Tinghua*(), WANG Lu   

  1. College of Resources and Environmental Sciences, Wuhan University, Wuhan 430072, China
  • Received:2021-07-17 Revised:2021-08-13 Online:2022-04-25 Published:2022-06-25
  • Supported by:
    Key Projects of National Natural Science Foundation of China National Natural Science Foundation of China(41531180)

摘要:

正六边形格网由于各向同性、邻接等效、拟合精度高等优点,被作为规则格网DEM数据结构的格网单元,已应用到流向分析、谷地线提取等数字地形分析中,但是其质量检测评价仍没有得到很好的研究,DEM的质量直接影响到后续数据分析结果以及相关决策的正确性与可靠性。使用常规的方法如检查点法、剖面法只能在局部评价DEM的误差情况,无法全面的评价DEM的质量。而等高线能够反映地形地貌的整体情况,因此等高线回放法通过分析回放等高线的质量,进而检测评价DEM的质量,是评价DEM质量的一种相对全面准确的方法。因此,本文将顶点高差标记法应用到六边形DEM格网结构中,为正六边形规则格网DEM提出了一种等高线生成算法,并对正六边形格网DEM的数据质量进行评价和分析。首先,本文利用生成等高线拓扑正确性、与原始等高线贴合度以及弯曲特征保持情况3个指标以评价六边形格网结构下的基于顶点高差标记法所追踪的等高线,其具有无自相交等拓扑错误、与原始等高线贴合度高、弯曲特征保持情况良好等特点,证明了该算法的可行性。此外,本文将该生成方法应用到不同规则格网DEM质量对比中,即基于顶点高差标记方法分别生成四边形DEM和六边形DEM的等高线,并基于上述3个指标对比六边形DEM和四边形DEM生成等高线的质量,从而进行六边形DEM和四边形DEM的质量差异比较,实验比较表明,在相同分辨率下,六边形DEM回放的等高线与原始等高线的贴合度更高,弯曲特征保持情况更好,并且随着分辨率的降低,其贴合度降低幅度较小,弯曲特征丧失较少,并未出现尖角化、形状过度变形等情况,因此六边形DEM的质量优于四边形DEM,并且随着分辨率降低,六边形DEM的精度折损程度更小。

关键词: 六边形格网结构, 六边形DEM, 顶点高差标记, 等高线回放法, 等高线生成算法, DEM质量评价, 等高线质量评价, 规则格网高程模型

Abstract:

Due to the advantages of isotropy, adjacency equivalence, and high fitting accuracy, regular hexagonal grid is used as the grid unit of regular grid DEM data structure and has been applied to digital terrain analysis such as flow direction analysis and valley line extraction. However, its quality detection and evaluation has not been well studied, and the quality of DEM directly affects the correctness and reliability of subsequent data analysis results and related decisions. Conventional methods such as checkpoint method and profile method can only evaluate the error of DEM locally, and cannot comprehensively evaluate the quality of DEM. Contour lines can reflect the overall situation of topography. Therefore, contour playback method is a relatively comprehensive and accurate method to evaluate the quality of DEM by analyzing the quality of playback contour lines and then detecting and evaluating the quality of DEM. Therefore, this paper applies the vertex height difference marking method to the grid structure of hexagonal DEM, proposes a contour generation algorithm for regular hexagonal grid DEM, and evaluates and analyzes the data quality of regular hexagonal grid DEM. Firstly, this paper uses three indexes: the topological correctness of the generated contour, the fit with the original contour, and the maintenance of bending features to evaluate the contour tracked by the vertex height difference marking method under the hexagonal grid structure. It has no topological errors such as self-intersection, fits well with the original contour, and maintains the bending features well, which proves the feasibility of the algorithm. In addition, this generation method is applied to the quality comparison of DEM with different regular grids, that is, the contour lines of quadrilateral DEM and hexagonal DEM are generated respectively based on the vertex height difference marking method, and the quality of contour lines generated by hexagonal DEM and quadrilateral DEM is compared based on the above three indexes, so as to compare the quality difference between hexagonal DEM and quadrilateral DEM. The experimental comparison shows that under the same resolution, the contour played back by hexagonal DEM has a higher fit with the original contour, and the bending feature is maintained better, and with the decrease of resolution, the decrease of fit is smaller, the loss of bending feature is less, there is no sharp angle, excessive shape deformation, etc. Therefore, the quality of hexagonal DEM is better than that of quadrilateral DEM, and with the decrease of resolution, the accuracy loss of hexagonal DEM is smaller.

Key words: hexagonal grid structure, hexagonal DEM, vertex height difference mark, contour playback method, contour generation algorithm, DEM quality evaluation, contour quality evaluation, grid DEM