基于动态四叉树索引的三维地质模型组合剖切算法

A Combined Cutting Algorithm for 3D Geological Model Based on Dynamic Quadtree Index

三维地质体模型可直观展示地质构造的空间发育形态,而地质构造的内部特征及构造间的复杂空间关系需通过连续的组合剖切和开挖分析进行揭露,并依赖于高效的基础剖切算法与剖切过程中模型数据的动态管理。该文针对以三角面片为基本数据结构的三维地质体模型,提出一种支持水平面剖切、竖直剖切、空间任意平面剖切等多种基本剖切类型组合的连续剖切分析方法。该方法通过引入动态四叉树索引,可快速定位剖切影响域三角面片,并依据交线位置关系快速生成剖面的轮廓多边形集合,进而经过多边形三角剖分形成地质剖面图;在连续多次剖切时,通过实时更新四叉树索引和剖切单元属性值,优化了组合剖切效率。实验结果表明,该方法可显著提高剖切计算速度,满足栅栏剖切、连续圆弧剖切、台阶剖切和开挖分析等复杂组合剖切与连续剖切分析功能。

Three-dimensional(3D)geological models usually make an intuitive illustration of the spatial development form of geological structures,while the internal characteristics of geological structures and the complex spatial relationships between them need to be revealed through continuous multiple cutting and excavation analysis,which depend on efficient basic cutting algorithms and the dynamic management of model data during the cutting process.In this paper,a continuous cutting analysis method is proposed for 3D geological models composed of triangles,to support the combined multi-step basic section cuttings,including horizontal section,vertical section,spatial arbitrary plane section etc.In this method,dynamic quadtree index is introduced,which can quickly locate the influenced triangles while cutting.A set of outline polygons of sections are quickly generated according to the positional relationship of the intersection lines between cutting sections and geological model triangles,and then a geological body section can be generated based on triangulation.In the continuous multiple cutting process,the efficiency of combined cutting is optimized by updating the quadtree index and the attribute values of section units in real time.The experimental results show that the proposed method can significantly improve the calculation speed of cutting,and support the combined cutting and continuous cutting analysis functions such as fence cutting,continuous arc cutting,step cutting and excavation analysis.