Research On Non-simulation Dynamic Visualization Of City 3D Model Based On Cesium

3D geographic information system(GIS)is the main research direction of GIS technology current and future.With the policy promotion and development of building smart city,3D GIS technology not only brings richer visual expression effects,but also provides more effective auxiliary decision support for various industries.For example,urban planning and management,building light analysis,urban waterlogging simulation,and urban energy consumption analysis.With the increasing demand for smart cities and the generation of multiple structural data,simple simulation and visualization can no longer be supported.Therefore,it is necessary to take the city target as the carrier of multiple semantics to complete the non-simulation visualization of the structural and dynamic evolution laws behind the complex urban morphology.Building is an important part of the city,so how to simplify,organize and express the 3D building model data effectively is the key problem to be solved at present.In this paper,through the analysis of the data of city 3D building model,combined with the characteristics of non-simulation visualization of city 3D model,with the goal of model simplification and multi-level-of-detail model construction and fusion of multiple semantic non-simulation visualizations to establish a non-simulation visualization system with multiple levels of detail for the 3D model of the city based on Cesium.It mainly includes the following three aspects:(1)Research on the comprehensive simplified algorithm of the fine city 3D building model.By analyzing the advantages and disadvantages of the traditional threedimensional building model simplification method,combined with the data processing method,this paper proposes a city 3D building model simplification method based on K-Means,and the data volume is greatly reduced without affecting the visual effect of the building model.(2)The problems related to multiple levels of detail in the 3D city model are discussed.According to a certain standard of detail level division of the model,the models with different levels of detail are extracted from the high level of detail models.In addition,the improved quadtree tile segmentation is performed on models with different levels of detail,and finally the data organization of the multi-level of detail model is completed.(3)By analyzing the mapping method of the visual variables to the semantic information in non-simulation visualization and the data format and organization method of loading 3D model in Cesium,using the 3D Tiles technology that loads a large number of 3D models and the CZML language describing the spatiotemporal dynamic scenes,the non-simulation dynamic visualization of the city 3D model is completed,and the application of the non-simulation visualization in the actual system is realized based on this.Through experiments,the model simplification method proposed in this paper has a good simplification rate.The multi-level 3D city model has a good visualization effect on the Cesium platform,and the actual non-simulation visualization system is realized.It is verified that the non-simulation visualization platform established in this paper has good feasibility and effectiveness,and can meet the requirements of non-simulation visualization with multiple levels of detail.