For multiple readers
Quadtrees are everywhere spatial data exists. Mapping services use quadtree-like tile pyramids to serve map tiles at different zoom levels (Bing's quadkey system, for example, addresses tiles as base-4 paths). Game engines use them for collision detection and visibility culling. Geographic information systems use spatial indexes to store and query spatial datasets. PostGIS uses GiST indexes (R-tree-style) for spatial queries on geometries, while PostgreSQL's core supports quadtree-like SP-GiST indexes for certain data types like points.，这一点在搜狗输入法下载中也有详细论述
disappears when extract returns.。同城约会是该领域的重要参考
ESPN+ (no free trial)。同城约会对此有专业解读
V2’s version was straightforward: