Research On SCSG-OSM Data Model And Its Application In Urban 3D Modeling

With the continuous advancement and innovation of the application of spatial information technology and the urgent need of Geographic Information System(GIS)theoretical methods in "digital cities",the theory and application of urban three-dimensional(3D)spatial models are particularly critical.In recent decades,the emergence of urban 3D modeling technology has provided basic data for digital/smart cities.Urban 3D modeling is different from traditional data,which has been transformed from two-dimensional(2D)data to 3D or higher dimensional data.It not only makes the map scene realistic and three-dimensional,but also facilitates spatial analysis and spatial decision making.In the process of urban 3D modeling,the building as the main body of urban construction,its modeling quality will affect the effect of the 3D model,so how to effectively integrate the urban building data,how to quickly update the 3D model in real time,how to achieve the detail analysis and dynamic processing of spatial objects have become the focus of research in the field of geographic information.Therefore,this paper studies the construction of urban 3D building model based on the research status of urban 3D modeling at home and abroad,and proposes the SCSG-OSM data model to reasonably express urban data.This data model has a simple structure and a small amount of data,which not only can accurately represent the topological relationship of spatial objects,but also quickly load texture images to achieve fast and accurate modeling effects,which has great research value.The SCSG-OSM data model proposed in this paper and its application in urban 3D modeling have the following aspects:Firstly,this paper conducts an in-depth study on the urban 3D modeling space model based on the current research status of urban 3D modeling at home and abroad,reviews a Simple Spatial Model(SSM),focuses on the definition and expression of 3D spatial objects,expounds the importance of the 3D model described in this paper using datasets to describe urban 3D modeling,and then discusses the necessity of constructing a reasonable urban 3D model of data organization.Secondly,this paper proposes an Object-based Spatial Model(OSM)method based on points,lines,surfaces and body objects.Firstly,based on the object-oriented thinking,the objects are summarized into four types of points,lines,faces and bodies,and are defined by data sets to form an OSM consisting of nine basic definitions.OSM is suitable for representing the elements inside the building model,and is relatively weak in representing the external shape of objects.Therefore,this paper uses the extended Dimensionally Extended Nine-Intersection model(DE-9IM)to judge the spatial relationship of ordinary bodies,and obtains the SCSG model to represent the shape of building.The SCSG-OSM data model is finally formed to collectively represent the urban 3D building model.Then,according to the SCSG-OSM data model,the data organization framework is constructed to organize and manage the data,and a spatial database is designed based on textures and SCSG-OSM.The database treats the texture as attribute data for the wall and top faces,and manages 3D building model by joint management based on file and object-oriented relational database.This joint management changes the complex process of traditional methods when calling texture images.Finally,according to the method proposed in this paper,the urban data is used to carry out the 3D modeling experiment,the process of 3D data visualization is analyzed,and the urban data is visualized in VRML,then a realistic urban 3D model is obtained.At the same time,the SCSG-OSM methods of this paper are summarized and analyzed by comparing the experimental results with the traditional methods,and the effectiveness of the method is demonstrated.