基于八叉树的复杂地质体块段模型建模技术

Study of Octree-Based Block Model of Complex Geological Bodies

为了有效地减少地质块段模型的数据量，提高建模过程中运算速度及准确性，采用八叉树结构表达块段模型，对三维目标空间进行块段细分；提出八叉树与有向有界箱（OBB）树相交测试算法以提高建模过程中的运算速度，同时改进射线法判断点在多面体内外及点在面状模型上下的算法，以确保复杂地质体块段模型建模的准确性．用C＋＋开发语言实现建模算法并与其它同类软件相比较，结果表明：采用该方法从表面模型到块段模型的转换速度比目前国际上常用的矿业软件要快30％～40％，结果准确，所需存储空间较小，便于空间检索与分析，对于地质模型的工程应用具有重要意义．

In order to reduce the data amount of geological block model, and improve the speed and accuracy of modeling, a block model was uses to subdivide the target area based on octree. An algorithm of the intersection test between octree and oriented bounding box （OBB） tree was proposed to improve the speed of modeling, and an algorithm for judgement a point in or out of a polyhedron and up or down of a face model was improved to avoid the false result. The algorithm of modeling was implemented with C＋＋. The results show that the algorithm have a time saving of 30%-40 %, compared with other mining software, during the conversion from the B-rep model to block model. The modeling result is accurate and easy for the query and analyze. It is significant to engineering application of the geological entity model.