为完成海洋项目总图编绘任务,在海底成图系统MBChart的基础上进行技术开发,提出面向海底地貌图编制的拓扑构建流程:通过曲线自相交、互相交来判断和删除悬挂弧段等操作,编辑不满足拓扑构建要求的弧段;以角度为序构建弧段的结点网络,建立弧段与结点间的双向联系;以结点为序跟踪相关弧段,构建封闭拓扑面;按照最小包围框初步建立各拓扑面间的嵌套关系,用射线法或转角法排除假嵌套关系,建立完整的拓扑树结构;在MBChart软件平台基础上,采用人机交互的方式编辑已构建的拓扑面,按照规范要求实现地貌图填色.已采用该技术方案完成海洋项目总图和《南海图集》中海底地貌图的编绘工作,同时该项技术还有望应用到地学研究的可视化展示和定量运算.
To design the maps of China's marine project, a mapping technology is explored on the basis of map software of MBChart, which has been established during a China's high-tech project from 1996 to 2000, a program of five-steps to establish topological tree is proposed to design submarine geomorphologic map. (1) Self-intersecting curves and intersecting curves and isolated arcs are found and edited until these arcs meet the rule of establishing the topological tree. (2) A nodes-network is established which is composed of the arcs extreme points, these arcs are appended to the node chain structure by the order of azimuth angle of closed two arc points, so the bidirectional relationship between the nodes and the arcs is established. (3)The topological area is established which is composed of the arcs traced from the nodes network. (4) The nested relationship of polygons is established through minimum external rectangle of polygons and the method of counting angles which are used to determine the relationship between the point and the polygon, the topological tree is established finally. (5) The topological areas are edited and the submarine geomorphologic maps are designed through man-machine conversation on the basis of map software of MBChart. The geomorphologic maps of China's marine project have been accomplished based on this program. The topological technology will be applied to the geology and geophysics study such as data display and complex area count.