Research On Multi-Scale And Progressive Transmission Of Cloud Management Platform For Three-Dimensional Territory

The three-dimensional territory management cloud pltform is the inexorable development trend of the territory informatization,and facing a huge challenge that massive territory data transmission and real-time rendering.Multi-scale model and progressive transmission technology are the key technologies to solve the problem of network transmission and real-time rendering of massive territory management data.In this paper,multi-scale model,progressive transmission,and data visualization have been realized which have been layed a solid technical foundation for the three-dimensional territory management cloud platform.Meanwhile,data prefetching,data caching and other technologies have been used to improve the performance of the multi-scale model and the progressive transmission prototype system.The main contents of this thesis are as follows:(1)In this thesis,according to the deficiency of Visvalingam-Whyatt algorithm and the characteristics of vector data,we proposed an improved Visvalingam-Whyatt algorithm,which effectively solves the problems of self-intersection of vector data and large memory when building multi-scale data.(2)A multi-scale model based on spatial grid have been proposed,which solves the problem of multi-scale storage,progressive transmission and fast retrieval of mass vector data while organizing multi-scale vector data.(3)Discussed the key technologies of progressive transmission: multi-threading,data removal,data prefetching.Progressive transmission framework for vector data contains a number of important tasks,each task is independent of each other and is accomplished by collaboration with multithreading technology;due to the large memory occupied by client for large data,the data removal algorithm is used to remove the data that will not be loaded temporarily;data prefetching technology is used to avoid loading data slowly.(4)The image preprocessing process have been described,which includes band extraction,band fusion,image stretching,image mosaic and image cropping.The problem of slow image segmentation and large memory occupation have been solved by pyramid algorithm based on line segmentation.(5)The multi-scale model and the progressive transmission prototype system have been discussed in detail.The system adopts the C/S architecture to realize the asymptotic receiving,reconstruction and 3D visualization of territory data.Moreover the multi-scale vector data and image data are generated by multi-scale construction tool of territory data.Finally,not only the performance evaluation method of 3D prototype system are given,but also the main performance of the system are compared,and the practicability of the system is proved.In this thesis,we study and improve the existing multi-scale models and progressive transmission methods,and develope the multi-scale model and progressive transmission prototype system.The experimental results show that the network transmission performance for large number data is better,and can meet the needs of practical application.