Research On Parametrization In Complex Three-dimensional Geological Modeling

With the continuous development of geological study,the three-dimensional modeling technology has been developed in a more realistic,accurate and scientific way in the aspects of spatial topology construction and internal attribute analysis,surface morphology and distribution of underground resources are presented in a visual way to provide a basis for resource development and utilization,has become a hot topic in computer science and technology,geostatistics,and digital multi-disciplinary research.The key problem of three-dimensional modeling technology is how to map the original discrete data obtained by exploration into the scientific geometric model data.Therefore,the establishment and perfection of the three-dimensional geometric model represented by the triangular mesh model have become the front and key issues of the three-dimensional modeling of the geological body.In recent years,3D geological modeling software has a rapid development,but there still exists the following problems:(1)Most of the modeling software has got some progress in the system functionality and diversity,but there is less attention in the model external beautiful degree,insufficient attention on inner quality optimization,such as the distortion exists in model texture map which cannot reflect the actual geological condition;(2)By reconstructing the sparse point clouds method or by other means,the triangular mesh model might capture the details of the object,but the grid vertex distribution,regularity,connectivity,triangle shape may not be able to meet the requirements of subsequent digital geometry processing,mesh simplification and Boolean operation also led to the quality problem of the grid model.(3)The geological structure modeling technology has mature was to deal with the common situation,but there are many shortcomings in the complex geological structure modeling which including the faults,fold structure,lack of deposition.In order to improve the grid quality and effect of geological model,this paper introduces the numerical geometric grid parameterization method into the geological modeling process.Although the research on grid parameterization has a great progress and there are a lot of parametric methods,but most of the parameterization method is based on simple grid,there are a lot of problem in the process of 3D modeling such as large amount of data and complex structure,and there is no parameterization method can well meet the requirements of the effect and time in digital geological model.For large grids,there still need for faster,less deformed parameterization methods,and the parameterization effects of many methods should be improved.For the complex situation in geology modeling such as texture mapping,surface reconstruction and fault,fold,we study different plane parameterization methods and the evaluation criteria of parameterization methods,based on this,we can find faster and optimized results to improve the quality of surface fitting,texture mapping and grid reconstruction,there is of great significance to promote the theory and method of 3d geological modeling and develop practical and commercial geological applications.The main research contents of this paper are summarized as follows:(1)Parametric theoretical study of three-dimensional model construction.There is investigation and analysis for the development of the parameterization and its application field,discussed the problems in geological model which is homeomorphic to a disk,roadway model and fault model such as deformation distortion in the texture mapping and overlapping cross of a triangle mesh,etc.,and the parameterization method is given to solve the problems.(2)The application of parameterization method in the process of complex geological modeling.Specifically studied the parameterization method of linear combination,harmonic mapping,conformal mapping,interval mapping and region growing,etc.,analyzed the features of the algorithm and the suitable areas,analyzed its applicable algorithm based on different geological model.The basic representation methods of the geological Grid are studied,and different parameterization methods for Tin and Grid meshes are designed.The general parameterization algorithm is used for the common geological surface which is homeomorphic to a disk,and texture mapping is used to evaluate the algorithm,the degree of deformation and the suitable situation.For the larger geological model,the initial curvature estimation and interaction segmentation are carried out.For the more complex fault,fold surface,we focused on analyzing its projection overlap,and for the roadway surface,combining with the geological characteristics,we adopt the regional growth method,we solved the problem such as the overlap in surface mapping,and the problem that complex geological model cannot be directly projected to the plane.(3)The research of point constraint texture mapping algorithm based on parameterization methods.For the problem of local positioning inaccuracies may arise in the process of texture mapping,the texture mapping algorithm based on feature points is studied.Using planar parameterization algorithm,3D complex geological model could be parameterized to the plane,through the system calculation and user interaction supplementary feature points as global parametric constraints,the geological surface feature point matching is achieved,and then the whole geological surface texture mapping is accomplished.(4)The research on complex geological surface regrid algorithm which is based on parameterization.Geological modeling using interpolation algorithm for initial data point interpolation processing to obtain a accurate 3D solid model,but common interpolation algorithm is not suitable for models which contains special terrain fault or fold,etc.In this paper,the complex geological surface regrid algorithm is studied.Combining the two dimensional plane domain resampling and inverse mapping algorithms,the common interpolation and triangulation algorithm of geological domain is chose to reconstruct a three-dimensional surface or topology.For complex geological model,such as fault or fold,2D reconstruction method to restore 3D surface is adopt,fault model based on TIN,is formed,the possible overlapping cross error conditions which occurred in reconstructing complex geological surface by common interpolation algorithm is avoid.(5)The parametric algorithm is verified and improved based on the actual geological modeling project.Take QuantyView as development platform,developed the complex three-dimensional geological model parameterized module,perfected the analysis module of 3D geological modeling and texture mapping function,designed and developed the function of complex geological surface heavy grids;After testing and integrating the various functions,take common geological surface,high curvature geological surface,the complex geological include fault and fold surface of Fuzhou,Nanjing,Changsha as example,the algorithm is analysis and verified.Results show that the method can be used to optimization and quality improvement of 3D geological model,based on the theory and application of model parameterization,further geological comprehensive analysis and research can be carried out,and the way how to solve other geological problems by parameterization principle can be discussed.This study is not only a subject in the field of geology,but also an interdisciplinary subject of comprehensive geology,differential geometry,geographic information system,computer graphics,etc.Therefore,this study helps to promote the application and development of the principles in all fields.Among them,the main innovation points are:(1)A texture mapping algorithm based on feature points is proposed.This method is used to carry out the geological feature point registration,in this way,the whole texture mapping of the geological surface is obtained,which can overcome the problem that the whole parameterized texture mapping method is difficult to accurately achieve local specific points.The problem that the existing equal-texture mapping method must be dependent on a limiting projective plane and the deformation of high curvature area has been solved.The texture mapping effect and accuracy of the complex geological surface model are improved.(2)A parameterized complex geological surface regrid algorithm is designed.For the distortion or overlap of the mapping grid,based on the parameterized algorithm,the 3D mesh is flattened to the two-dimensional plane domain and resample.The topology of triangulation network is constructed by using the reconstruction algorithm,a smooth surface grid is created.Finally,the spatial triangulation network is restored through the corresponding relationship between the sampling point and the original 3d grid,the complex geological surface regrid is accomplished and the internal details of the grid are not deformed or overlapping.(3)The application of parametric method in 3D geological modeling is explored.The complex 3D grid surface problem is reduced one dimension,the improved algorithm is in the process of texture mapping,grid editing and surface reconstruction,the geometry of the original grid is maintained and the distortion is reduced.A new method of computer science and technology is applied to the traditional geological modeling system.The system with new technology is improved and update,a new way to solve the problem is provides,the application level of geology is deepened.