Chapter 5 Spatial Queries
译:章节5 空间查询
The raison d’etre of spatial databases is to perform queries inside the database which would ordinarily require desktop GIS functionality. Using PostGIS effectively requires knowing what spatial functions are available, how to use them in queries, and ensuring that appropriate indexes are in place to provide good performance.
译:空间数据库存在的理由是在数据库内部执行查询,这通常需要桌面GIS功能。有效地使用PostGIS需要知道哪些空间函数可用,如何在查询中使用它们,并确保适当的索引到位以提供良好的性能。
5.1 Determining Spatial Relationships
译:5.1 确定空间关系
Spatial relationships indicate how two geometries interact with one another. They are a fundamental capability for querying geometry.
译:空间关系表示两个几何图形如何相互作用。它们是查询几何图形的基本功能。
5.1.1 Dimensionally Extended 9-Intersection Model
译:5.1.1 尺寸扩展9交模型
According to the OpenGIS Simple Features Implementation Specif