An Effective Tile Caching Mechanism of UAV Remote Sensing Map Based on Hilbert Coding Index

The Unmanned Aerial Vehicle (UAV) remote sensing system has become one of the most important tools for the acquisition of modern remote sensing data. The map generated by UAV remote sensing images is expected to be widely used in resource monitoring, post-disaster reconstruction and so on. Tile cache is an important way to speed up real-time loading of tile map. In order to accelerate the tile loading of UAV map, we take advantage of data locality principle and user behavior to build Hilbert coding index for each level in the tile pyramid. Then, we propose a neighborhood prefetching cache strategy, which is analyzed from the two dimensions of width and depth on the basis of Hilbert coding index. Compared with a simple strategy taking single tile as cache granularity, this caching strategy improves cache hit ratio and reduces average response time of tiles significantly. Meanwhile, Redis as the cache database, which not only supports the persistence of memory data, but also has the advantages of high development efficiency and strong scalability.