一种消除三维地质模型边界裂缝的锁边LOD方法  

An Edge-locking LOD Method for Eliminating Boundary Cracks in 3D Geological Models

作　　者：王振娟 花卫华[1] 刘修国[1] 郑鹏[1] 肖旖旎 闻龙 WANG Zhenjuan;HUA Weihua;LIU Xiuguo;ZHENG Peng;XIAO Yini;WEN Long(School of Geography and Information Engineering,China University of Geosciences,Wuhan 430074,China)

机构地区：[1]中国地质大学(武汉)地信学院,武汉430074

出　　处：《地球信息科学学报》2023年第5期967-981,共15页Journal of Geo-information Science

基　　金：国家重点研发计划课题(2019YFC0605102);国家自然科学基金项目(41972307)。

摘　　要：本文针对采用传统LOD生成算法快速渲染大范围三维地质模型时连续性差的问题,提出一种消除三维地质模型边界裂缝的锁边LOD方法。(1)使用多级图划分算法并通过并行计算将网格分块问题快速转化为图分区问题,根据空间相邻关系将三角网格划分为一系列大小相近的集群和集群组;(2)基于二次误差测量的网格简化算法锁定集群组边界进行简化以生成更高层级的LOD数据,在简化时通过增加边界边权值实现集群组的锁边简化,自下而上地构建起不同级别集群和集群组的依赖关系;(3)有效生成模型各级LOD渐进数据块,并采用分页机制编码数据块。本文使用基于钻孔数据所构建的三维地质模型,对模型执行集群和集群组的划分、约束外边界的网格简化等操作来构建LOD,并对LOD数据进行编码。实验结果表明本文方法可生成各级简化率约为50%的LOD以消除三维地质模型高低精度数据块之间的裂缝,实现了三维地质模型可视化时较好的连续性表达,为地下空间透明化和大范围地质模型可视化提供支撑。In response to the problem of poor continuity when using traditional LOD generation algorithms to render large-scale 3D geological models,this paper puts forward a kind of edge-locking LOD method to eliminate boundary cracks in 3D geological models.To begin with,the triangular grid partitioning issue is quickly transformed into a graph partitioning problem using a multi-level graph partitioning algorithm,which divides the triangular grid into a series of clusters and cluster groups of similar size based on spatial adjacency and executes the multi-level graph partitioning algorithm with parallel computation to improve the partitioning efficiency.Next,the grid simplification algorithm based on quadratic error metric locks the boundaries of cluster groups for simplification to generate higher level LOD.In the simplification phase,edge-locking simplification is achieved by increasing the boundary edge weights of cluster groups at each level of LOD,while at the same time,DAG dependencies of clusters and cluster groups at different levels of LOD are constructed from the bottom up.Finally,the LOD progressive data blocks at all levels of the model are efficiently generated and the paging mechanism is utilized to encode cluster and cluster group data blocks,thus taking full account of the spatial adjacency of the data and DAG dependencies so that a minimum number of Pages are loaded simultaneously at runtime.In this paper,the 3D geological models with different scales and complexity constructed from borehole data are selected for data validation,in which A is constructed from 189 borehole data to obtain 21 standard strata with a data size of 50MB and an area of 3337 km2;B is constructed from 6489 borehole data to obtain 43 standard strata with a data size of 139 MB and an area of 123 km2.After accessing the data file in Obj format,the LOD is constructed by performing operations on the model such as delineation of clusters and cluster groups,mesh simplification of constrained outer boundaries,as well as encoding the cluste

关 键 词：LOD 三维地质模型 裂缝 锁边 集群 集群组 多级图分区算法 QEM算法 

分 类 号：P628[天文地球—地质矿产勘探]