引用本文: 魏小峰, 苗双喜, 濮国梁, 陈波, 程承旗. 应用于六边形网格的链码方法[J]. 武汉大学学报 ( 信息科学版), 2019, 44(11): 1700-1707.
WEI Xiaofeng, MIAO Shuangxi, PU Guoliang, CHEN Bo, CHENG Chengqi. Chain Code Methods for Hexagonal Grids[J]. Geomatics and Information Science of Wuhan University, 2019, 44(11): 1700-1707.
 Citation: WEI Xiaofeng, MIAO Shuangxi, PU Guoliang, CHEN Bo, CHENG Chengqi. Chain Code Methods for Hexagonal Grids[J]. Geomatics and Information Science of Wuhan University, 2019, 44(11): 1700-1707.

Chain Code Methods for Hexagonal Grids

• 摘要: 目前只有顶点链码能够直接用于表达六边形网格边界。将典型的四边形网格链码推广应用于六边形网格，并提出了新的链码方法，其中，六方向Freeman链码（F6）对边界网格中心连线的6个绝对方向进行编码；左右二方向链码（left right 2-direction chain code，2LR）通过记录外轮廓前进的两个相对偏转方向实现对边界的表达；单调性标识链码（monotonicity identify chain code，MICC）通过区分码标识沿网格边界的单调性变化；边链码（edge chain code，ECC）则是将每个边界网格在外轮廓上的边数作为其码值。对4种方法的几何特性、表达效率与压缩性能进行了全面比较与分析。实验结果表明，这4种方法均能有效应用于六边形网格形状的边界表达，其中，ECC和F6的表达效率最高，平均码数约为1；2LR与ECC的压缩性能最好，与F6相比，压缩率可达67%。

Abstract: Only vertex chain code can be used directly to express hexagonal grid boundary. The classical chain codes for quadrilateral grids are modified and extended to apply to hexagonal grids, and a new chain code is proposed. Among them, 6-direction chain code (F6) encodes the 6 absolute directions of the adjacent boundary grid. Left right 2-direction chain code (2LR) records the two deflections along the contour move direction to realize the expression of boundary. Monotonicity identify chain code (MICC) marks the changes of monotonicity along the grid boundary by distinguish code. Edge chain code (ECC) records the edge numbers in the outer contour of each boundary grid as its code value. Moreover, the geometric properties, the expression efficiencies and the compression performances of the four chain code methods are compared and analyzed comprehensively. Experimental results show that four methods can effectively express the shape boundary in hexagonal grids, where ECC and F6 have the highest expression efficiency, the average code number per grid is about 1; 2LR and ECC have the best compression performance, compared with F6, the compression rate of which can reach 67%.

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