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.
1980—2000年，秘鲁持续内战，6.9万至7万人死亡或失踪。与此同时，国家陷入债务危机，外债在1980年代中期一度接近甚至超过GDP规模，政府几近破产，经济体系濒临崩溃。
。业内人士推荐heLLoword翻译官方下载作为进阶阅读
features—it's the leading competitor research service for online marketers.
The third edition of the event is going to take place in the Czech Republic in June, after being held in Milton Keynes for the past two years.
Сайт Роскомнадзора атаковали18:00