Research On Interactive 3D Geographic Scene Building Method Based On WebGL

The theme of this research is using multi-source spatial data to build thematic geographical scenarios swiftly.The traditional spatial information processing methods have been unable to meet the demand of massive data storage,calculation and analysis of large amount of space-time data with the rapid development of emerging mapping and Internet technology,specially in the areas where the people,logistics and information are concentrated,the application of spatiotemporal data is even more difficult.After the WebGL standard is put forward,a large number of Web-based 3D GIS applications emerge,the focus of users on 3D WebGIS is gradually shifting from the stacking of map layers to the construction and application of specific 3D scenes.However,the existing methods of spatial data expression mainly focus on the visual display of one or some kinds of spatial data,lacking of effective support for multiple models and devices.The fragmentation of multi-source heterogeneous data also makes it difficult to support geographic analysis,and the links of multi-scale data are lack of setting basis.In the past,the method of expressing spatial data in the way of factors layering lacks the fusion of real-time dynamic target and 3D static geographical scenes.It is impossible for people to participate effectively in the abstract structure of the real world and in the process of observing the geographical phenomenon and its evolution in all directions,ignoring the perspective of the person who is the cognitive subject to observe the world daily.In order to solve the above problems,new management,processing and visualization modes of data are urgently needed to transform the big data of time and space into the information and knowledge needed by people.Geographical scenes,as carriers of geographic information,contain spatial entities and their spatial distribution within a specific region,which is the main object of describing natural and humanistic elements.This article uses the concept of geographic scene to present an interactive three-dimensional geo-scene construction method based on WebGL.Based on the composite pyramid,this method establishes the necessary scene construction rules and provides rich and flexible interactive functions and realizes the heterogeneous data in the data rendering layer fusion and the scale seamless link through the Graph function library transmission format.It finally realizes unifies the multi-scale data in a three-dimensional scene,the service geography national condition monitoring,the emergency disposition,Large-scale geographic information applications,virtual reality and other fields.In order to realize this technical method,this paper focuses on the following aspects of the work:1)This paper studies the content and classification of scene data and existing multi-source spatial data organization theory,discussed the multi-source and heterogeneous data to form a scene of technical methods,to lay a theoretical foundation for the establishment of scene building rules.The mathematical foundation and rendering principles of WebGL are analyzed in depth,and glTF is a data specification for network transmission and GPU rendering,the data structure and rendering principle are clear,which lays the foundation for mapping geographic scene to computer screen and isomorphism of scene data.2)An open scene data organization model for the construction of geographic scene is designed,which takes the discontinuous LOD structure as the core,and designs the data isomorphic technique for various spatial data based on glTF format,which provides flexible and efficient data support for the expression of thematic scene.3)Design three-dimensional geographic scene expression model aim at the browser,based on the compound pyramid model and combined with the specific needs of people,we develop the rules of scene construction for multi-scale spatial data,a flexible scene editing wizard is designed for the interaction between the scene building and the interaction between the human and the scene.On the basis of the scene expression model,the realization mode of online scene service and the deep application of 3D geographic scene are discussed.4)In three-dimensional geographic scene data organization model and the expression model based on research results,build platform was designed and implemented the geographical scene,and service stations in the actual project,the multi-scale expression of campus scene,building communities of components query and structure decomposition and monitoring and management of library,gymnasium and other indoor scene.In this paper,the study of interactive scene construction methods combined with relevant experiments shows that interactive 3D geographic scenes can realize the combined application of multivariate heterogeneous spatial data in a lightweight manner.This construction method embodies good interactivity and is organized rationally.Several kinds of spatial data and non-spatial data take into account the application of personalized scenes,and also support transaction data data and real-time data expansion flexibly,providing services for the deep application of three-dimensional data.