spatial queries

DM-77 - Spatial Joins

The measuring (or query) of the relationship between spatial features is of particular utility within a GIS. A spatial join combines represented geographic objects and their associated attributes based on a spatial relationship test (or predicate). The method of spatial join operation utilized depends on the relationship between the features represented and how those features are represented in the GIS.  Regardless of the software implementation, the spatial join operation results are predicated on a test condition such as adjacency, proximity, or topology comparison among represented geographic data. This topic discusses how spatial join operations can be utilized for different geographic problems.