A Presentation Method Of 3D Dynamic Natural Disaster Symbol Based On Particle System

In recent years,natural disasters have occurred frequently all over the world,and countries have paid more and more attention to disaster prevention and mitigation.Using surveying and geographic information methods to assist emergency rescue is an effective means of strengthening emergency surveying and mapping service capabilities.As an important part of the system,the map representation of natural disasters can intuitively present disaster information through electronic maps,providing a spatial reference and visual expression basis for disaster prevention and mitigation applications.Driven by information and communication technology,maps have broken through the two-dimensional and paper-based limitations,realized three-dimensional and multi-dimensional expressions in digital space,and opened many emerging visualization methods.Symbols of natural disaster maps have also been developed from two-dimensional and static abstract expressions to three-dimensional and dynamic image expressions.However,the current research on the symbolic representation of natural disaster maps remains at the two-dimensional and static level,and there is a lack of research on the three-dimensional symbolic representation of the natural disaster phenomenon ontology.Moreover,due to the characteristics of irregular and dynamic changes in natural disasters,it is difficult to express them effectively by traditional geometric modeling methods only,so new symbolic modeling methods need to be introduced.Aiming at the shortcomings of the existing research on the representation of threedimensional map symbols of natural disasters.This thesis draws on the expression of natural phenomena in the 3D game engine,chooses to use particle system technology to realize the modeling of 3D natural disaster map symbols,and proposes a 3D dynamic natural disaster symbol representation method based on particle system.This thesis first studies the principle of symbolic modeling of natural disasters based on particle systems,expounds the basic ideas of particle systems,focuses on the general structure and model building principles of particle system parameter models,and explores the billboard algorithm for particle system model rendering.In addition,according to the characteristics of visual expression of natural disasters,the common expression patterns of particle systems in the construction of natural disaster symbol models are classified,which lays a theoretical foundation for the construction of natural disaster map symbol models.Secondly,the thesis explores the natural disaster symbol design method based on particle system,summarizes the static,dynamic and interactive visual variables of 3D map symbols,and discusses the overall and individual visual expression parameters of particle system.And the mapping relationship between visual variables and particle system visualization parameters is summarized.Based on this,this study explores the application of visual variables in the design of natural disaster map symbols,and supports the symbolic representation method proposed in this thesis from the perspective of map symbol visual variables.Finally,this thesis sorts out the Web GL,Web animation and other related technologies needed to realize the particle system in the network environment.Based on the three.js three-dimensional visualization framework,the prototype system of the symbolic representation method proposed in this thesis is designed and implemented.And the prototype system is used to verify the symbolic representation method proposed in this thesis.