Cesium-Based WebGIS And BIM Integration Study

With the development of the times and the progress of science and technology,the demand for urban geospatial informationization from all walks of life has become more and more urgent,and GIS(Geographic Information System)has gradually transitioned from the traditional object-oriented mode to the service-oriented mode.Along with the continuous development and improvement of geospatial information,multi-dimensionality,multi-source,multi-model,multi-scale and network of geographic information will become the future development trend of GIS.Although the traditional technology of GIS cannot meet these requirements,with the in-depth research of multi-source GIS data model and the further development of computer technology,the above difficulties will be solved.On the one hand,the emergence and development of Java Script and WebGL technology to overcome the Webfront-end rendering spatial data and visualization problems;3DTiles and other three-dimensional data standards to improve the speed of loading and rendering models of a large range of three-dimensional scenes,breaking through the limitations of the network transmission of large amounts of threedimensional data model is difficult.On the other hand,building information modeling(Building Information Modeling,BIM)can refine the expression of the internal details of the building,through the WebGIS integration of BIM technology will achieve a full range of application analysis of the three-dimensional scene model,which not only achieves the integration of internal and external modeling and application of large urban scenes,but also provides the spatial attribute information of the building model.make geospatial information realize comprehensive perception,sharing and integration.The purpose of this paper is to study the 3D model Webservice technology and the difficult research problems faced by the integration of BIM and WebGIS,and to study the technologies related to the conversion of BIM and GIS model data and 3D model loading and rendering,and to build a WebGIS Webservice platform based on Cesium that integrates BIM technology.The main work and results are as follows:1.Aiming at the data format difference between BIM model and GIS model,the key technical issues of data conversion and function realization in the integration process of WebGIS and BIM are proposed by studying the differences between the two data standards in geometric expression,data expression,semantic expression and spatial scale expression.2.For the data conversion problem in the process of WebGIS and BIM integration,the mapping method of geometric and semantic information between the two is studied based on model differences,and the IFC data model is converted into CityGML data model to realize the conversion of BIM data to GIS data.3.For WebGL to realize fast transmission and parsing and loading of 3D models on the web side,based on the characteristics of CityGML 3D model data,we further convert CityGML model to 3DTiles data model applicable to Cesium from the development and web service level,solving the problems of rendering efficiency and network transmission limitation of 3D model data,and realizing seamless conversion of BIM and WebGIS data visualization and sharing seamlessly integrated.4.Based on the conversion of BIM and GIS model data and solving the web service,the interactive technologies such as visualization and functional analysis of urban building spatial data are designed to realize the WebGIS and BIM integration system based on Cesium,which validates the theory of this paper and lays the foundation for the integrated application of BIM technology and GIS technology.