| With the increasing demand for spatial data services,the construction of smart cities and smart campuses has gradually unfolded.In the construction of smart campuses,the establishment of a 3D navigation system is crucial.Compared to traditional 2D map navigation,the spatial queries and path planning functions of a 3D navigation system can present more intuitive and accurate geographic information,helping users better understand building layouts,traffic flow lines,and service facilities,bringing users more efficient and convenient experiences.Therefore,the construction of a high-precision and realistic indoor-outdoor 3D navigation system is one of the important contents of urban digital construction,which is of great significance and role in the construction of smart cities and smart campuses.The core technologies of 3D navigation include spatial positioning,3D model visualization and its publication,and road network construction and pathfinding.In this thesis,an outdoor 3D model was constructed using oblique photogrammetry measurement technology,and an indoor3 D model was constructed using BIM technology.These two models were integrated and unified to build a 3D road network.Using Cesium development technology,an integrated indoor-outdoor3 D model scene was constructed,and a web-based indoor-outdoor integrated 3D navigation system was developed.In-depth research was conducted on the two key elements of 3D model visualization and its publication,as well as road network construction and pathfinding.The specific research content and achievements are as follows:(1)Research on Construction of Indoor and Outdoor 3D Models.A comparative analysis was made on the construction methods of 3D models,including their principles,technical advantages and disadvantages,and applicable scope.The necessity of using oblique photogrammetry to construct outdoor 3D models and BIM to construct indoor 3D models was discussed.An experiment was conducted to construct indoor and outdoor 3D models,and the oblique photogrammetry model was individualized.In addition,lightweight processing technology was used to convert BIM 3D models into the 3DTiles format supported by Cesium,laying the foundation for subsequent research on integrated indoor and outdoor models on the web.(2)Research on Integrated Indoor and Outdoor Road Network and Path Planning.The spatial characteristics of indoor and outdoor spaces were analyzed,and the construction methods of existing road network models and commonly used path planning algorithms were compared.The most suitable method for constructing a three-dimensional indoor and outdoor road network and path planning was selected.A three-dimensional integrated road network was constructed on the indoor and outdoor 3D model in the research area,and the shortest path was calculated and presented using path planning algorithms.(3)Research on Cesium-based Three-dimensional Visualization of Indoor and Outdoor Spaces.The advantages of developing applications based on Cesium on the web were analyzed and discussed in depth.The feasibility and advantages of rendering indoor and outdoor 3D models using the Cesium engine and implementing three-dimensional navigation on the web were discussed.Additionally,research was conducted on how to use Cesium technology to load multiple data sources,flatten 3D models,and navigate through scenes.The role and advantages of these technologies in practical applications were explored in depth.(4)Design of an Integrated Indoor and Outdoor Three-dimensional Navigation System.Based on the research on key technologies such as indoor and outdoor 3D model construction and road network model construction,a three-dimensional navigation system was designed and developed using Cesium technology.The system provides a complete development process for an integrated indoor and outdoor three-dimensional navigation system by integrating threedimensional road network models and path planning algorithms.The system fully utilizes the high resolution and scene-realistic restoration ability of oblique photogrammetry models and the high precision and refinement characteristics of BIM technology.Additionally,it demonstrates the powerful rendering capabilities of Cesium in large-scale applications,providing good promotion for research on integrated indoor and outdoor three-dimensional navigation. |
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