Study On The Three-dimensional Dynamic Scenario Deduction In The Ice Flood Process

The ice flood disasters of the Yellow River are frequent,and the Inner Mongolia reach has become one of the most serious sections of the Yellow River ice flood disasters due to its special geographical location and climatic conditions.With the improvement of ice control requirements,the traditional two-dimensional ice flood process research has been difficult to meet the needs of ice control and disaster reduction.Therefore,it is important to realize the three-dimensional dynamic scene deduction of ice flood process,so that ice flood workers can intuitively understand the shape,layout and evolution law of ice movement in the three-dimensional virtual scene.It plays an important role in disaster prevention and mitigation and ice flood characteristics analysis.This work relies on the national key research and development program sub topic "R&D and demonstration of Yellow River intelligent ice flood prevention platform(No.2018YFC1508506)".In this paper,the Toudaoguai reach of the Yellow River in Inner Mongolia is taken as the research object.Based on the measured three-dimensional river topography,the numerical simulation of ice flood process under different conditions is carried out based on the mechanism of river ice dynamics.Combined with virtual simulation technology,three-dimensional dynamic visualization of two-dimensional simulation data of ice flood process is realized in the virtual scene.The development and optimization of ice flood simulation system are realized through script programming and system scenario optimization technology.The system has good interactive function and visual effect,and has been applied in the intelligent ice flood prevention platform.The main work and research results are as follows:(1)Numerical simulation of ice flood process:the numerical simulation mechanism of ice flood process is analyzed.Based on the measured river topography,three ice flood processes with given initial conditions are simulated and deduced,and the main transportation.law of the ice freezing in the study curve is obtained.The density of flow ice gradually increases from upstream to downstream,and flow ice accumulation is easy to appear on the concave bank with low velocity.The ice jam in the bend leads to the high water level in the upstream,and the water flows into the beach to form a solid ice sheet.The larger the flow rate is,the smaller the development of ice floating density is.Ice jam is easy to occur in the bend and narrow channel,resulting in high water level,and there is a significant positive correlation between discharge and water level;The water temperature changes dynamically below 0℃ and the water temperature in the river beach is obviously lower;The ice jam in the bend can reduce the velocity of the river.(2)Virtual scene construction:the terrain information of the study area is obtained by UAV oblique photography,single beam bathymetry and other technologies,and the river water and underwater terrain construction is completed with ContextCapture and other software;Based on BIM Technology,the parametric model of river related buildings is constructed,and the attribute information of BIM model is retained;The ice models of different sizes are built based on 3DMax,and the model optimization technology,UVW mapping and rendering technology are used to enrich the expressiveness of ice models;Finally,the above models are imported into unity3d to build a high degree of restoration three-dimensional scene model as the carrier of ice flood deduction.(3)Ice flood process scenario deduction:in order to optimize the expression of two-dimensional data,ArcGIS platform and VBA macro-processing technology are used to preprocess the ice flood process simulation data,and based on C#language,the two-dimensional output information can be read in the three-dimensional scene.Through unity3d virtual engine,based on fixed grid,the three-dimensional dynamic deduction of ice flood process multi elements(water depth,ice,water,flow velocity,flow direction,water temperature,ice floating density,etc.)in the virtual scene is realized.(4)Development of ice flood three-dimensional scene deduction system:in order to enhance the expressiveness,combination and practicability of three-dimensional dynamic scene deduction model,the ice flood simulation system is developed based on C#programming language.The system includes scene loading,user interface,virtual roaming,ice flood deduction,system interaction,data management and other functional modules;In order to ensure the smooth operation and display effect of the system,the system scene is optimized by using instantiation technology,occlusion culling technology,levers of detail technology,collision detection technology and so on.