Method Of Web Digital Earth Ocean Vector Field Data Dynamic Visualization Based On The Particle System

With the development of digital earth technology and the concept of "next generation digital earth",digital earth will focus more on platform construction and solving major problems such as environment,health and social welfare.The report of the 18 th National Congress of the Communist Party of China puts forward that "improving the capacity of marine resources development and resolutely safeguarding the national maritime rights and interests,building a strong marine power",based on the digital earth system to simulate the marine environment,it deeply excavates the laws behind the ocean and conformed to the development trend of digital earth significantly.As an important part of the marine environment simulation,the study on the dynamic visualization method of marine vector field data is indispensable.At present,there are three problems in the research of dynamic visualization for marine vector field data at domestic and abroad: one is visualization and effect,that is,we choose the appropriate method to model the ocean vector field so that it can be vivid and intuitive.And the status of vector field can dynamically and continuously show the basic trend and law of vector field.In addition,it is difficult to observe the vector field with three-dimensional,multi-angle.Second,the scalable visualization engine,many Web's marine environment data visualization engines are not a complete WebGIS engine,and it is difficult to freely expand the system.Third,the large-scale visual scene rendering efficiency,because the WebGL standard is newer,many Web threedimensional scene acceleration methods are not mature,so the common efficiency improvement method is as little as possible rendering scene content,so the efficiency of the increase is not large.In the view of above three problems,this paper introduces the SPH real-time fluid simulation method,SPH principle simplified marine vector field visualization method,the building of Web digital earth system based on Cesium and the rendering acceleration algorithm of large-scale 3D visualization scene Research and implementation,and the main results achieved are as follows:(1)A method of SPH real-time fluid simulation based on WebGL technology is proposed.This paper presents a SPH real-time fluid simulation method framework based on multi-frame buffer for WebGL technology.For the characteristics of WebGL technology,it should use the GPU with multiple texture buffer to store the particle location and the relevant intermediate information.At the same time,the search algorithm of domaining particles is optimized by dynamic attribute method,and the search efficiency of neighborhood particles is improved.The efficiency of this algorithm is twice as high as GPU-based Bayraktar algorithm,and it can meet the frame rate requirement of 3D scene rendering at Web front end.when the number of particles increases to 50 k,it will further increase.(2)A dynamic visualization method of marine vector field data with SPH principle is proposed.Based on the WebGL-based SPH real-time fluid simulation method,and according to the real-time characteristics of marine vector field data and its application range,the formula of SPH method is simplified.The algorithm formula Re-derivation,and finally gives the entire algorithm to achieve the flow chart.The core of complex SPH method is applied to the dynamic visualization of the ocean vector field,which makes the expression of ocean vector field more layered and realistic.(3)a large-scale vector field data visualization scene rendering acceleration method is achieved.This paper comprehensively studies and implements a variety of rendering optimization algorithms.WebWorker multithreading and V8 engine hierarchical memory reclamation algorithms are used to calculate and update the state of each particle in the particle system in real time,and the GPU is accelerated by multiframe buffer to realize the rapid update rendering of the scene.The experimental results show that the number of particles can be increased by more than 100,000,and WebCL can be used to enhance the efficiency of neighborhood particle search by 3 times,and the WebWorker multithreading is used to increase the speed by at least 2 times when calculating the current particle state information.when multi-frame buffer GPU acceleration is used,the speed of drawing and updating 200,000 particles is 2 times than the traditional CPU and GPU method,and the integrated above methods makes the rendering frame rate of entire scene from 5 frames increased by about 15 frames.