Application Research Of 3D Model Visualization Of Oblique Photography Based On WebGIS

With the rapid development of digital earth and smart city,urban spatial data has attracted extensive attention from all walks of life.How to integrate and analyze the massive urban data is the current focus of research on the establishment of smart cities.Urban 3D model has a high degree of scene restoration and 3D visualization.The construction of urban 3D model and the management and utilization of 3D model have a high application value for the construction of smart city.The traditional manual modeling method is no longer suitable for building large-scale urban models.Oblique photogrammetry has become an important means of acquiring three-dimensional geospatial information in smart cities.The rapid development of computer technology and the maturity of 3D technology brought opportunities for using oblique photography model.The 3D WebGIS technology can be combined with the 3D model of tilt photography effectively to realize the efficient utilization and management of the 3D models.In this paper,based on the tilt photography data and other urban spatial data,Cesium 3D visualization framework and B/S framework are adopted to establish a 3D model visualization platform to realize the dynamic visualization analysis of the tilt 3D model and provide auxiliary decision support for urban planning.The main content and research results of this paper include:(1)This paper introduces the related theories of tilt photography in detail;the acquisition of oblique photography data,reconstruction of 3D model and data format are introduced and analyzed in detail;the 3D reconstruction technology is used to realize the construction of 3D basic data scene and the transformation of the inclined model data to the data supported by Cesium.(2)In this paper,the monomer model of tilt photography is studied in detail,three common monomer methods of tilt photography are introduced,and a dynamic monomer model is realized by combining WebGIS technology and tilt model through comparative analysis.The dynamic monomer of the tilt model requires the acquisition of the bottom data of the building.This paper starts from the three-dimensional point cloud and uses the combination of Ran SAC algorithm and Alpha Shape algorithm to extract the boundary of the point cloud.Then,B-spline curve fitting is used to achieve the fitting of the contour of the three-dimensional point cloud.Experimental results show that this method can effectively extract the building contour and provide basic data for the subsequent implementation of query management module of inclined model.(3)This paper builds 3D WebGIS visualization platform based on Cesium framework,uses B/S framework to realize visualization application of urban spatial data,and designs and builds three modules in detail: 3D measurement module,3D analysis module and query management module.The three dimensional measurement modules include two dimensional plane measurement and three dimensional space measurement functions.The 3D analysis module contains five commonly used 3D GIS analysis functions,including sunshine analysis,inundation analysis,height acquisition,buffer analysis and viewable range analysis.The main function of the query management module is to query the information of the building.By superimposing the contour extracted from the 3D point cloud experiment and the inclined 3D model,the query relation is constructed,and the relevant information of the 2D plane layer is presented on the client through 3D rendering.The WebGIS 3D model visualization platform built in this paper can conduct comprehensive and multi-level analysis and management of 3D models,and it can provide powerful technical support for urban management,which has high practical value.