Research On Multi-scale Visualization Of Large-scale 2D/3D Data Based On Cloud Rendering

The representation of geographic information has always been the basic research subject of geographic information science.People’s representation of the real world has experienced the evolution process from text to graphics to GIS data.At present,the ability of twodimensional GIS to express information has been unable to meet people’s rich application requirements.Compared with two-dimensional GIS,three-dimensional GIS can represent geographical elements in a more intuitive way and express richer content.With the progress of computer technology and mapping equipment,three-dimensional data acquisition methods have become diversified,such as lidar,laser scanning,photogrammetry,etc.The continuous progress of these technologies makes the acquisition and processing of three-dimensional data more efficient,and its cost is gradually reducing.In this context,the application of 3D data has shown explosive growth,and the Ministry of Natural Resources has also carried out the construction of 3D projects across the country.Therefore,the application of geographic information system is gradually developing to three-dimensional.Multi-source data obtained by different sensors need fusion modeling to form a 3D model of reality.Taking land traffic scene as an example,this paper discusses the method of fusion modeling of oblique photographic data and laser point cloud data,etc.After format conversion and data organization,the 3D model of reality can form a unified whole with the BIM model to meet various functional requirements.The advantage of 3D data is that it can provide a more intuitive and realistic visualization effect,but at the same time,due to its large amount of data and the shortcomings of rendering computation,resulting in high performance requirements for the client,the need to configure high-performance CPU chips and graphics cards,but also not conducive to network transmission,there is also the risk of data leakage.With the development of Internet +technology and intelligent terminal equipment,the application of GIS has gradually shifted to mobile terminal.Mobile devices have many advantages,such as portability,versatility and universality.These advantages make mobile devices an ideal platform for obtaining and using geographic information applications.At the same time,with the improvement of Internet speed and the popularity of mobile terminal devices,mobile terminal devices are more and more able to meet users’ needs for real-time,fast and efficient geographic information services.How to achieve real-time,high-quality and smooth visualization in low-performance clients(laptops,mobile phones,tablets,etc.)is a problem that needs to be solved.Based on the game engine UE4,the cloud rendering system of 2D and 3D data is designed and realized.According to the user’s instructions on the terminal,the large-scale 2D and 3D data required by the user is rendered on the server side and transmitted to the user in the form of video stream.What the client displays is only a video stream,which greatly reduces the computing load of the client side.At the same time,the problem of data confidentiality is solved.To achieve a low performance notebook,mobile phones,tablets and other mobile devices can also obtain high-quality,smooth visualization,while having a good interactivity.The function of space interval measurement and space analysis is realized by using C++ and blueprint programming.It provides a reference for large-scale 2D and 3D data rendering.