| In recent years,with the rapid development of geographic information systems(GIS)-related mobile technologies,mobile GIS-related technologies have become the predominant method in geological survey.As the core and basic function of GIS,spatial data visualization is one of the priorities for the development of GIS.Unlike PC devices,mobile devices are limited in performance,especially in the performance of CPU and the size of RAM.It’s important to achieve the acceleration of spatial data visualization on mobile.This paper studies the following four aspects and provides a solution to accelerate spatial data visualization for mobile GIS:1)it studies the three-level cache structure of "memory-disk-offline map package",increasing the reuse rate of the tiles and making grid map can be loaded without network;2)it studies a multi-threaded tile acquisition and asynchronous update mechanism,it designs a complete set of multi-threaded task scheduling methods to accelerate the grid tile acquisition process.Additionally,the overlay rendering of raster space data and vector space data is implemented to complete the map service function;3)it studies the application of levels of detail ideas and pyramid model in vector space data loading.The research on the classification,rarefying,and cropping of vector space elements lays a foundation for the leveled and block-based display model of spatial data;4)developing a prototype system based on GeoGIS.Through the early design and the later development,the scheme of accelerating spatial data visualization has been put into use.The use results show that the map visualization efficiency is improved obviously. |
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