Algorithm Research On Non-topologically Consistent Three Dimension Geological Block Modeling

3D Geological Modeling is a new technology of geological research,which combines Spatial information management,Geological interpretation,Spatial analysis and prediction,Geostatistics,Entity content analysis and Graphical visualiz ation with computer technology in virtual 3D space.Normally,the technology constructs a geological space model to describe geological regions through three sub-processes: Surface modeling,Block modeling and Attribute modeling.The model can visually display the geometric features to users and can also be used as the foundation of ohter works such as forward simulation after being filled the attributes.Therefore,this technology has great application value in many fields such as hydrology,engineering,environment,earthquake prediction,regional geological survey,mineral resource exploration,mine design,mine production and management,urban geological exploration,urban underground space management.Since the birth of 3D geological modeling,Geological block modeling has always been one of the difficulties and key points of this technology.According to the principle of realization,the traditional geological block modeling algorithm can be roughly divided into function fitting type,voxel split type,hybrid type and surface stitching type.Among all these types,the surface stitching type is one of the most common and intuitive algorithm.Before adopting the surface stitching algorithm to perform geological block modeling,it is usually necessary to perform a series of operations such as surface intersection and cutting to the target geological space model to make the geological space topologically consistent.After which the algorithm can find the outside surface of block based on the topological relationship among geological surfaces to achieve block modeling.When the geological model is complex,the topological operation may make the triangular mesh dense near the intersection line and the size of it vary greatly.At the same time,due to the float precision,computers may get distored results while calculating the float data with excessive different magnitude,which leads to the topological relationship error among the surfaces,and geological bolck modeling method that depends on the topological relationship invalid.In this paper,a series of researches on the geological block modeling algorit hm based on the surface-stitching type are carried out.The surface-stitching type algorithm has been improved after the implementation of the traditional method,the dependence on the topological relationship of intersection lines in geological space was reduced,and it can handle the geological space model with a few topological errors.In addition,this paper provides a new non-topologically consistent 3D geological block modeling algorithm,in which the geological space will be firstly lattice partitioned with octree grids division,then grouping the partitioned meshes to obtain the approximate shape of each block,at last an algorithm similar to visual observation and decesion mechanism will be used to extract the outer surface corresponding to each geological block.This algorit hm can perform geological block modeling without relying on the original inter section topological relationship during the geological surface,and the errors in the subsequent block modeling results due to the imprecision of the operations can be avoided.Experiment shows that he algorithm works fine for both topol ogically consistent models and non-topologically consistent models,and the correct and reliable results can be obtained with limited space-time resources.