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.
The Artemis III mission, which had been expected to land astronauts near the moon's south pole in 2028, now will be redefined and rescheduled — launching in 2027 but not to the moon, Isaacman said. Instead, the yet-to-be-named astronauts will rendezvous and dock in orbit closer to home with one or both of the commercially built lunar landers now under development at Elon Musk's SpaceX and Jeff Bezos' Blue Origin.
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研发强度并未随“分子”研发投入的规模变大而递增，由此可见，企业研发强度受“分母”营收规模的影响似乎更大。随着营收规模扩张，企业往往将资源倾向市场扩张等方向，反而淡化了研发投入的紧迫性。
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