Research On The Method Of Oblique Photography Monomer Based On Cesium Framework

With the rapid development in the construction of “Smart City” in China,the urban correct 3d model has a broad application prospect and inestimable economic value in the current social development.As an important infrastructure for the construction of the “smart city,” the actual 3d model of the city bears the basic data information of the city.The development of oblique photogrammetry technology(OP)and the continuous progress of 3d visualization makes it possible to achieve large area 3d modeling in high efficiency and short time,which provide important basic data for the construction of “smart city” in China.However,the technical mechanism of OP automatic modeling determines that the output model can't distinguish individual features physically,whereas it is a continuous TIN network.However,for most applications of the OP 3d model,the most fundamental GIS functions like the selection of single features and the assignment and query of the attribute are needed,which makes the monomer of 3d model a complex problem in GIS.The realization of monomer can break the limited function that oblique photographing 3D model can only roam and browse,and carry out more precise ground feature management.In this paper,the treatment method of the monomeric OP 3d model is deeply introduced,and the WebGIS platform built by Cesium open-source framework is put forward combined with the existing methods.Finally,the monomer of OP 3d model is accomplished on these bases.Main work of this paper is as follows:(1)In this paper,the OP technology,acquisition process,and data processing key technologies of OP data,application of OP technology,data format,and conversion methods of OSGB and 3DTiles are introduced in detail.The mechanism of data conversion is stated definitely,while the actual data is displayed under the data convert method.(2)The related technologies of WebGIS visualization,Ceisum open-source earth platform,and its framework structure are presented in particular.This paper mainly introduces the technical basis of Cesium open-source digital earth platform from the aspects of visualization technology,Web-related technology,WebGL technology,3d WebGIS technology,etc.,in which the rendering principle and process are explained in detail in WebGL technology,and the theoretical basis of web rendering techniques are provided to the Cesium framework.(3)This paper focuses on the causes of the monomer problem of the OP 3d model,then the realization methods of monomer are classified and explained from the aspects of cutting object monomeric method,ID monomeric method,dynamic rendering monomeric method,and the others.Several methods are compared and analyzed after the explanation of the implementation principle and technical core.Finally,the Cesium framework is used to construct a WebGIS platform to realize dynamic monomer rendering of inclined photographic 3d model.(4)In this paper,the method of constructing a WebGIS platform is programmed and explained based on the Cesium framework,and finally,a prototype system of the local WebGIS platform is formed.The method and process of the monomer module are described,while the module is embedded into the WebGIS platform system based on the Cesium framework.Then the transformed 3DTiles data is loaded,and the effect of the monomer is finally demonstrated.Finally,the length measurement module and perspective analysis module are embedded in the platform for improving the application,and the effects are shown by examples.The results show that the effect of the monomer presents good feasibility,which indicates a high practical value of the method.With the better openness of the Cesium framework,different modules can be added to it in the actual project application.