Multi-scale And Multi-attribute Coupling Mechanism Of Urban Geological 3D Modeling

Focusing on the problem of multi-scale and multi-attribute coupling mechanism faced by urban geological 3D modeling,taking Wuhan urban geology as the background,applying the theories of fractal geometry,cartography and vector grid integrated 3D geological modeling technology,the following innovative achievements have been achieved:1.Introduce fractal geometry and relevant theories of cartography to solve the multi-scale coupling mechanism of urban geological 3D modeling.Due to the complexity of geological conditions,the scarcity of modeling data and the difference of modeling requirements,it is urgent to solve the problem of multi-scale and multi-attribute coupling mechanism in urban geological 3D modeling.Based on the criterion that the aspect ratio represents the distribution shape characteristics of geological body,this study determines the two-dimensional minimum modeling object representing the horizontal modeling scale.On the basis of revealing the mechanism of the horizontal and vertical grid fitting geological body error of urban geological three-dimensional modeling voxel,based on the minimum modeling object on the two-dimensional plane and the thinnest modeling stratum in the vertical direction,the multi-scale characteristics of voxel in threedimensional spatial grid division are determined,The multi-scale feature coupling mechanism of modeling voxels in three-dimensional space is revealed,and the problem that it is difficult to determine the size of modeling voxels under the constraint of equal error between horizontal distribution and vertical thickness fitting of mass in grid is solved.2.Based on the attribute of "knowledge element",a multi-attribute fusion mechanism of 3D geological modeling at different scales is established to realize the unified management of "knowledge element" at different scales.Based on the "knowledge element" with model voxel attributes that store different geological attribute information,the multi-attribute fusion mechanism of three-dimensional geological modeling with different scales is established by using octree data structure method;Taking the three-dimensional spatial location information and scale information of "knowledge element" as the only spatial index code,the unified management of geological information stored in all "knowledge elements" of different scales in the construction of three-dimensional geological model database is realized,and the big data technology is applied to solve the management efficiency problems of data storage,query and retrieval of threedimensional model database.3.Based on the requirements of modeling accuracy and model application for modeling scheme and later model management and updating,as well as the constraints of modeling data,scale,geological background and software and hardware environment on the formulation,accuracy and application of modeling scheme,the suitability evaluation system of urban geological 3D modeling is developed.The abundance and deficiency of modeling data is analyzed by borehole density,and the evaluation standard of abundance and deficiency of modeling data is constructed based on the relevant standards and technical specifications of hydraulic environmental geological survey and urban geological survey with different scales in China;The complexity evaluation index factors of geological background conditions in the modeling area are obtained by using the fractal dimensions of all map spots.Based on the multi-scale analysis of modeling voxels,the positive correlation between different voxel subdivision scales and modeling accuracy is determined and tested.On the basis of revealing the restriction mechanism of each index on modeling quality and modeling efficiency,the suitability evaluation index system of urban geological 3D modeling is constructed.4.The quantitative evaluation system of the multi-scale 3D geological model accuracy based on the stratum equal depth sampling and comparison of strata thickness solves the problem of automation and batch by simple calculation and programming,avoids the influence of human subjective factors,and the application verification and accuracy rate is 95.24%;Using python programming method,the automatic algorithm of quantifying the accuracy of 3D geological model is realized,and the key technical problems of urban geological 3D modeling are solved.