Large-scale River Rendering Of Inland River Ship Handling Simulator

The reality of river scene is one of the important evaluation indexes for inland ship handling simulator,and the realistic river simulation scene is the key to improve the training quality of inland ship handling simulator for inland crew.So,aiming at the urgent demand of enhancing the reality of river scene in inland ship handling simulator,this thesis proposes the solving model for river velocity field on the basis of the river modeling theory and method,and realizes the real-time rendering with higher reality for large scale river scene of inland ship handling simulator.The modelling of river flowing and real-time rendering of river surface are two key issues in the river visual simulation of inland ship handling simulator.And the key premise is the modeling of river flowing which was based on the method of wave spectrum.However,this method cannot reflect the flowing character of river that is the main character distinct from sea water.The river simulation’s first concern is to build the model of river flowing which can generate realistic velocity field.Then a continuous river surface is necessary for reflecting river flowing in render stage.However,the river flowing will cause texture deformation of water surface,which lead to the river surface distortion in the process of rendering.Therefore,it is necessary to solve the contradiction between the river flowing and keeping texture attributes,and consider the requirement of real time rendering of river scene.Based on the above considerations,firstly in the aspect of river flowing modelling,the approach for building the river velocity field based on the procedural method is proposed.This method is mainly to use the stream function’s characteristics for solving river velocity field,which can reduce calculation and realistically express for the river flowing,the fundamental thought of solving the river velocity field is using inverse distance weighting method for building stream function in river channel.At last,several river channels in the electronic river map of inland ship handling simulator,such as single river channel,branching river channel and complex river channel with fixed obstacles,are used to simulate above models and algorithm,and the simulation result shows that the proposed model for solving river velocity field can be applied to various complex river terrain,the solved velocity field can reflect the river flowing characters realistically,and also conform with the coupling relationship of river velocity field and river width.Secondly,in the real-time rendering of river surface aspect,the texture mapping of river surface based on the texture block is proposed.In order to balance the display effects and simulation efficiency,a fast algorithm for generating Poisson disk sampling points based on the river boundary control is proposed,the samples in the river channel can be generated and be used to control the texture distribution,then the solved river velocity field can drive the texture block.This method can reflect the solved river velocity field realistically and generate the continuous moving river surface.Besides,in order to realize the real-time rendering for large scale river scene in inland ship handling simulator,the TDF algorithm is improved based on the solved velocity field,and with combining GPU,GLSL shader programming and LOD technique,the large scale river scene,such as river,terrain and various building,can be real-time rendered.The effect of river reflection can ben realized with the cube mapping and planar reflection.At last,the simulation results indicate that the proposed algorithm can be used to construct river scene with realistic virtual environment which also meet the real-time requirement in simulation.In conclusion,this thesis solves the difficulty of real-time river simulation in inland ship handling simulator,its research result can be applied in various complex river channels to present the river moving characteristics realistically and renderlarge-scale river scene in real time.Hence,the proposed method in this thesis can enhance the visual reality in the inland ship handling simulator,and provide high realistic simulation scene to operator.