Design And Realization Of BIM+GIS 3d Campus Visualization System

The construction of three-dimensional campus visualization has been widely valued and developed in the past few years.On the one hand,the content displayed by most of the three-dimensional campus visualization systems is relatively simple,and the systems aren’t able to show the internal structure and component information.On the other hand,some of the systems lack the design of suitable geographical space analysis,which makes it difficult to provide the reference for the management and planning of the campus.With the development of building information model(BIM)and geographic information system(GIS),carrying out the research on the key technologies of BIM + GIS Integration for social application has been put forward in the 13 th five-year plan of the development of Surveying and mapping geographic information technology.Aiming at the above problems,BIM + GIS technology was used in this paper to build a prototype system based on a university,which provided convenience for teachers and students in the University,and integration for the administrators of the buildings as well.In such way we can achieve the purpose of cultural publicity of the university.The main work of this paper is as follows:(1)Considering the lack of building internal structure and component information of the existing campus scene model,this paper studied the three-dimensional parametric modeling which based on BIM Technology.The campus remote sensing satellite map,CAD drawing,architectural texture and Revit modeling tools were used in this paper to complete the campus topography,building facade modeling,indoor Scene modeling and campus environment combined with the different characteristics of scene elements.(2)As for the selection between Bim and GIS platform and model differences,we used cesium.js as the mapping engine of which the Web GL is the bottom layer,to build a threedimensional Web GIS platform,we analyzed the data formats of gl TF,B3 DM and3DTiles.With the secondary development of Revit,we uesd the model element as a unit,uncoupled its geometry and texture data and then saved it into obj format.in consideration of the problem of loading delay caused by large amount of data and triangles in obj model,we used the spatial octree structure to manage and segment the model,and used the edge folding algorithm of approximate curvature to simplify the triangle mesh to achieve the lightweight of the model.After that,we studied the transform of data format from obj to3 DTiles in the perspective of geometry,coordinates and attribute data,and BIM model is loaded into Web GIS platform.(3)Design and development of 3D campus visualization system.We firstly analyzed the user needs and the design rules of BIM + GIS,and divided the system architecture into four layers.Secondly,from system function perspective,we designed the map display module,building BIM information query module,spatial GIS analysis module and the corresponding query module and then realize the sub functions of these modules.