Research On 3D Realistic Simulation Of Crude Oil Leakage Accident In Mountainous Area

The data of crude oil leakage in mountainous areas are generally obtained by numerical calculation with computational fluid dynamics method.This kind of software can only calculate the numerical simulation data in a small calculation domain,which can not be effectively displayed for the environment outside the calculation area.In the application of decision support,we usually use all kinds of information needed for largescale terrain bearing decision,and make a clear visualization of the actual situation by mapping the data to the terrain surface.This thesis presents a method to map the numerical simulation data of crude oil leakage to the large-scale topographic grid,and then optimize the visual effect of the leakage area on the topographic grid.It provides an effective solution to the problem that numerical simulation data can not be directly used for visual display in decision support applications.The primary problem studied in this thesis is the method of mapping the numerical simulation data of crude oil leakage in mountainous areas to topographic grid.Numerical simulation data are usually stored in the form of Irregular Triangulation,which is different from the terrain of quadtree structure composed of multi-resolution tiles,resulting in difficult mapping.In this thesis,a multi-stage optimized TIN to terrain grid mapping method is proposed.Firstly,tiles within TIN coverage are extracted by fast retrieval on quadtree terrain.For the terrain vertices on the covered tile,the mapping is completed by finding the triangle and interpolating,and calculating the vertex attribute value.A method of using k-d tree to find the nearest point and judge the most likely triangle first is proposed to optimize the mapping efficiency.A two-stage boundary optimization method is proposed to optimize the visual effect of the boundary shrinkage problem caused by only the internal point assignment of TIN.This thesis also focuses on the interpolation optimization method of visualization effect of leakage area on topographic grid.For the terrain grid with numerical mapping,the simple interpolation method causes jagged inner and outer boundaries,and the visualization effect is poor.Relatively complex smooth interpolation methods,such as bicubic interpolation,have many sampling points.When interpolating tiles,it is difficult to obtain the sampling points of tile edge elements that are not on this tile.In this thesis,a calculation method of bicubic interpolation algorithm on multi-resolution terrain tiles is proposed.A method is proposed to establish an expanded imaginary neighborhood of tiles,assign values to the vertices of imaginary tiles,and then obtain all the sampling points required for tile interpolation.The interpolation problem on multi-resolution terrain is decomposed into the assignment problem of imaginary neighborhood on each tile.The lower resolution of each hypothetical tile in the same direction is proposed.Bicubic interpolation on multi-resolution terrain is realized.The simulation of crude oil leakage accident on mountainous terrain is realized in three-dimensional experimental environment.The simulation results have smooth visualization effect and high realism,and the visualization efficiency can meet the needs of real-time simulation.