Research On Multi-Dimensional Display And Cache Optimization Of Five-layer Fifteen-level Remote Sensing Tiles On Mobiles

With the rapid development of mobile communication technology and remote sensing technology,mobile GIS application has become a focus in GIS research area.As a new type of remote sensing data organization model,The Five-layer Fifteen-level model can effectively process and store massive remote sensing images,and can also solve the problems of complex processing and precision loss in traditional image organization models,and can make it effective to use massive remote sensing images in mobile application.As we can say this model has very important practical value.However,as the basis of the application,the research on the visualization of Five-layer Fifteen-level remote sensing tiles in mobile terminals only stays on the 2D platform without considering the adaptability to map development frameworks and the characteristics of mobile devices.In addition,the 3D display research is still blank.Based on the above problems,this thesis studies multi-dimensional display and cache optimization,and provides an effective framework for the multi-dimensional display of Five-layer Fifteen-level remote sensing tiles in mobile terminals.The research contents of this thesis are as follows:(1)Combining the characteristics of the Five-layer Fifteen-level model and mobile devices,this thesis proposes a complete multi-dimensional display method for Five-layer Fifteen-level remote sensing tiles on mobile terminals.For the two-dimensional display,this thesis studies the tile projection transformation of tiles which can prevent internal deformation,and constructs a new hierarchical correspondence relation which adapts to different map development frameworks,thus effectively solving the adaptability of the model and the map framework;this thesis also developes a prefetching strategy which can speed up the display speed of the interface and a lagging unloading strategy which can avoid the splash screen problem,to improve the efficiency and smoothness of the interface display.For the three-dimensional display,this thesis designs a tile data structure adapting of the Five-layer Fifteen-level model,establishes a node evaluation system quantifying the drawing precision,and develops a real-time view data scheduling strategy ensuring the application to run smoothly,to make up for the lack of relevant research on 3D display.(2)Based on the 2D display characteristics of Five-layer Fifteen-level tiles in mobile terminals and users' operational preference,this thesis defined the concept of tile distance value.Then combining time value,tile size value and multi-attribute decision-making thoughts,a cache replacement algorithm based on tile space-time operation(TSO)is developed.The performance comparison experiments show that the algorithm has advantages in cache hit rate and is more suitable for medium cache space.In addition,this thesis also designed the cache structure based on the experimental results,which effectively reduces the network transmission cost between mobile and serve,and speeds up image display.(3)This thesis constructs a mobile multi-dimensional visualization system for massive remote sensing images based on the Five-layer Fifteen-level model.More concretely,using 2D display,3D display,cache prefetching,network services,multi-threaded concurrency and hybrid cloud architecture,this thesis implements multi-dimensional,multi-scale visualization of Five-layer Fifteen-level multi-temporal high-segment slice data,and develops field plotting assistive function for mobile terminal.This thesis verifies the feasibility and effectiveness of the visualization application model,in the meanwhile it implements the on-demand expansion and rapid response of the massive remote sensing information service in the mobile application system.