Methods of High-Precision Vector Line Modeling in Discrete Global Grid Systems
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[目的]全球离散格网系统(Discrete Global Grid Systems,DGGS)本质上是多尺度栅格结构,地理空间矢量与格网的集成是难点,矢量线格网化是其中的基本问题.现有方案多以平面格网单元中心(格心)连线为矢量线建模结果,但扩展到球面后建模精度降低,本文针对这一缺陷提出矢量线全球离散格网系统高精度建模方法.[方法]首先选择与地球拟合程度更高的菱形三十面体构建六边形格网系统,以3个相邻菱形面构成组合结构并建立三轴整数坐标系描述单元空间位置;然后根据矢量线首尾端点所在单元确定最优方向编码以减少搜索范围,通过编码邻近运算搜索矢量线经过的球面单元,以球面格心连线为建模结果并提出跨面矢量线处理方法;最后增加单元顶点(格点)作为结构要素,实现多结构要素矢量线建模,进一步提高建模精度.[结果]实验结果表明:本文方案能正确实现全球各个大洲海岸线格网化建模,确保格网化单元与矢量线拓扑相交,且相较平面格网建模结果兼具精度和效率优势.[结论]针对传统矢量数据格网建模方法的几何精度损失和拓扑畸变问题,本文提出高精度球面格网化建模方法,为矢量数据转换至格网同构处理提供有力支撑.
[Objectives]Discrete Global Grid System(DGGS)is a hierarchical structure with seamless global coverage.It functions similarly to an electronic table covering the Earth,supporting the processing and analysis of heterogeneous geospatial data.However,the grid is essentially a multi-scale raster structure,and integrating geographic vector data into it remains a challenge in both research and application.Vector data includes points,lines,and polygons,among which vector line gridding is a fundamental problem.Most existing solutions express vector lines using the center lines of grid cells on a planar grid.However,when extended to spherical surfaces,the accuracy of vector data modeling decreases,making it difficult to meet application requirements.[Methods]This paper proposes a high-precision modeling method for vector lines in DGGS.First,a hexagonal global discrete grid is constructed based on the rhombic triacontahedron,which offers a higher degree of conformity to the sphere.Three adjacent rhombic faces are combined to form a composite structure,and a three-axis integer coordinate system is established to describe the spatial positions of hexagonal elements.Based on the grid cells corresponding to the start and end points of the vector line,optimal direction codes are determined to reduce the search range.The great arc of the vector line passing through the cells is identified using a neighborhood encoding operation.The resulting model is constructed based on the connecting line between grid centers,and a method for processing cross-surface vector lines is proposed.Finally,grid vertices are introduced as structural elements to enable vector line modeling using multiple structural elements,further improving the accuracy of hexagonal grid-based vector line modeling.Experiments show that the proposed method successfully models the grid representation of major coastlines across different continents.The results ensure that the grid model intersects with the original vector line topology,avoiding topological errors where original vector lines do not intersect with any grid cells.[Results]Compared with planar grid modeling,the proposed method achieves significantly higher accuracy in vector line gridding across various coastal regions worldwide.The modeling results demonstrate strong stability and are nearly unaffected by the resolution of the original vector data.Moreover,the method maintains an efficiency advantage,even after complex geometric operations on the spherical surface.[Conclusions]To address the geometric accuracy loss and topological distortion issues in traditional vector data grid modeling,this paper proposes a high-precision spherical grid modeling method.The approach shows strong potential to support the conversion of vector data to grid-based isomorphic representations.
vector linesrhombic triacontahedronDiscrete Global Grid Systemmulti-structural elementsdata modelinghigh precisionhexagonencoding operations
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