A contour generating algorithm for solving excursion of geochemical concentration focus
REN Ze1, LIU Xiu-Guo1, ZHANG Jian-Bo1, GAO Yan-Fang2
1. Faculty of Information Engineering, China University of Geosciences, Wuhan 430074, China;
2. Institute of Geophysical and Geochemical Exploration, CAGS, Langfang 065000, China
Grid and TIN are usually used during the computer graphics of medium-large scale geochemical contour maps; nevertheless, the former generates the problem of "excursion of geochemical concentration focus", while the latter can't ensure smooth contours as well as regular border. Aimed at solving these problems, this paper presents a contour generating algorithm for discrete data based on extreme points constraint. Firstly, the original sampling points and grid points are merged. Secondly, the abnormal grid points are rejected. Finally, triangulated irregular networks and track contour lines are built. The original sampling points and grid points are merged to improve accuracy and visualization of contour lines. The experimental results show that geochemical concentration focus coincides with extreme points in the contour map generated by this method, which is visually smooth and edge-expanded.
[1] 吕国安.成矿区带地球化学异常评价方法[M].北京:冶金工业出版社, 2002:17-19.[2] 韩小明,张晓梅,王瑞,等.地球化学等值线图生成方法研究及相关软件使用对比[J].新疆地质, 2007(3): 327-330.[3] Wang Z W, Zhu C Q, Wang Y G.The reconstruction and applications of the contour lines based on TINs[C]// Proceedings of the 8th International Symposium on Spatial Accuracy Assessment in Natural Resources and Environmental Sciences. Shanghai: 2008: 100-106.[4] Sohler C.Fast reconstruction of delaunay triangulations[J].ComPutationalGeometry,2005,31:166-178.[5] 王万银,邱之云,刘金兰,等.位场数据处理中的最小曲率扩边和补空方法研究[J].地球物理学进展, 2009(4): 1327-1338.[6] 宋敏,张见明,覃先云.基于格网DEM的自适应等值线图及UG实现[J].微计算机信息, 2010(30): 181-182.[7] 胡金虎.基于不规则三角网的高精度等值线生成方法[J].工程勘察, 2011,(02): 64-68.[8] 王学春,尚继宏.三次贝塞尔曲线拼接模型的折线式等值线曲线化应用[J].测绘科学, 2011(2): 192-194.[9] 边淑莉,柳佳佳,王海龙,等.基于规则格网DEM的等高线提取算法的优化与实现[J].测绘科学. 2008(6): 151-153.[10] 胡德鹏,黄晓萍,任年海.基于不规则三角网(TIN)的追踪等值线算法及对等值线光滑算法的研究[J].计算机与信息技术, 2006(3): 46-48.[11] 吴凡,粟卫民,杨英伟,等.基于联合Delaunay三角网的等高线地形特征提取研究[J].中国矿业大学学报. 2007, 36(2): 172-176.[12] 郑春燕,郭庆胜,胡华科,等.基于约束Delaunay三角网建立等高线层次结构的方法[J].武汉大学学报:信息科学版.2008, 33(5): 524-527.[13] 罗明良,汤国安.地貌认知及空间剖分的山顶点提取[J].测绘科学, 2010(5): 126-128[14] 陈仁喜,龙毅.顾及三角形处理的TIN建立算法[J].武汉大学学报:信息科学版.2003(5): 619-622.[15] 徐道柱,刘海砚.大量约束边条件下Delaunay三角网的快速生成[J].测绘工程.2007(3): 6-10.