Study On Algorithms For Three-dimensional Modeling Of Complex Strata

As a critical part of3D GIS and digital mine, algorithms for strata3D modelingplay a very important role in production, safety, management and decision-makingof coal mine, and have become a hot spot. The algorithms based on facial models cannot nicely express the stratum’s solidness. Among algorithms based on volumetricmodels, a voxel only expressing one geo-body and allowing no fault across it.therefore, when modeling for strata containing special geo-bodies, either wrongresults were generated(when not taking boundary constraints into account) or theautomation level of them were decreased greatly(when taking boundary constraintsinto account), Moreover, many algorithms process special geo-bodies independently,and the models of special geo-bodies were not fused with the models of stratacontaining them.Referencing modeling methods based on facial models and volumetric models,regarding3D modeling for strata of coal mine as research object, aiming at highautomation of modeling, with volumetric models as the core, highlighting thesolidness of stratum, emphasizing the idea of seamless fusion, innovative studies on3D modeling of complex strata have been undertaken.(1) Aiming at the problems that a single GTP(Generalized Tri-Prism) can notcontain two or more kinds of geo-bodies and can not be passed through by faults, avolumetric model which can solve them named virtual Generalized Tri-Prism ispresented. Based on it, a3D hierarchical structure model named " virtual GeneralizedTri-Prism-Polyhedron-Tetrahedron " is put forward which rightly solved theproblems of modeling of all special geo-bodies and the seamless fusion with strata.(2) Quickly and reasonably constructing stratum surface TIN, fault surface TINforms the basis of3D modeling for complex strata. After importing TIN template andputting forward methods of contour elevation interpolation and points elevationinterpolation of stratum containing faults based on the idea of polygon partition, anintegrated solution of creating continuous stratum surface TIN, surface TIN of stratumcontaining faults and fault surface TIN is proposed. The constructed TINs havestructured feature and provide great facilities for VGTP generating.(3) Adopting divide-and-rule idea, based on regular block grid and quadtree, twopractical methods for dividing strata space are presented, which can reduce difficultyand complexity of3D modeling for large area containing multiple faults and can make results reasonable and accurate. A method for seamless fusion among models ofsub-blocks is put forward.(4)3D hierarchical structure models expressing single-fault strata, multi-faultsstrata, strata containing lenticular-body and intrusive-body, wedge-out-body andfolding-body are brought forward separately and relevant modeling algorithms arealso designed which can greatly reduce manually interactive operations and gainhigher automation level.(5) The basic requirement of3D-Hierarchical-Structure-Model is the procedure oftransformation from polyhedron into tetrahedron, therefore, the transformationalgorithm is of importance in the paper. From two angles of polyhedron’sgeometrical feature and Constrained Delaunay Tetrahedralization of arbitrary region,after analysing current typical algorithms, two highly-efficient algorithms fortransformation from polyhedron into tetrahedrons are presented.The modeling algorithms have been applied to modeling for actual complex strataof coal mine and expectant effects have been gained.