| Dam-break flood simulation can provide information like flood depth and flow velocity,and construct 3d flood disaster scene by using flood simulation results,which can help to provide auxiliary decision support for flood control and disaster reduction,so as to minimize disaster loss.However,the existing 3D flood disaster visualization scenes have problems such as low efficiency of large-scale evolution simulation,simple disaster information and unclear expression,which are difficult to effectively support efficient simulation and analysis of large-scale dam-break flood disaster.Therefore,this paper focuses on the study of visualization optimization simulation method of large-scale dambreak flood disaster,breakthroughs in key technologies such as flood evolution simulation calculation efficiency optimization and 3d flood disaster scene visualization guided by disaster information constraint rules,and develops prototype system and carries out case analysis.The main research results and concrete work are as follows:(1)A parallel calculation method for dam-break flood evolution simulation based on Open MP is designed.Firstly,the method of flood evolution calculation based on cellular automata is discussed,and the parallel principle and method of Open MP are introduced.Then,a dynamic parallel method considering load balancing is proposed.The design and implementation of parallel scheme are given.The data interaction mechanism and access conflict control strategy of parallel threads are designed.Finally,the performance of Open MP parallel computing is further optimized by merging parallel regions and privatizating the variables of reduce operation.(2)A visualization method of 3d flood disaster scene suitability constrained by disaster information is proposed.Firstly,the general idea of 3d flood disaster scene visualization is given,the flood disaster conceptual scene is constructed,and the disaster composition and characteristics are analyzed.Then,the disaster information constraint rules considering spatial semantics,attribute category,disaster association and disaster expression are established.Finally,the visualization process and fusion modeling strategy of 3d flood disaster are designed to realize the construction and fusion of basic geographical scene,3d flood model and disaster information model,and complete the suitability visualization expression of disaster information in 3d flood disaster scene.(3)Design and develop a prototype system and conduct case experimental analysis.Based on the above research results,Visual Studio 2013,Qt5.8.0,Open MP,OSG and GDAL are used to design and develop the dam-break flood disaster evolution simulation prototype system with 4170×4680 data.The 3d dam-break flood evolution model and visualization scene are constructed,and the experiments are carried out.Experimental results show that the final speed-up ratio of the dynamic parallel method presented in this paper reaches 8.13,saving 87.7% of the calculation time at the highest,and improving 10.6%of the speed-up ratio compared with the static parallel method.Through qualitative comparison and analysis with other visualization methods of flood disaster scene,the suitability visualization proposed in this paper can achieve reasonable and clear expression of disaster information in the 3d disaster scene,and enhance the readability of disaster information. |
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