Spatialrefsys
Spatialrefsys, typically implemented in a PostGIS environment as the spatial_ref_sys table, is a catalog of coordinate reference systems (CRS) used to interpret and transform spatial data. It provides a centralized registry that maps human-readable CRS identifiers to machine-readable definitions, enabling consistent handling of geometry coordinates across databases and applications.
The table stores metadata for each defined CRS. Core columns commonly include a srid (integer, the unique
Entries are usually sourced from standard authority datasets such as EPSG, but databases may also include custom
Users typically query spatial_ref_sys to discover the SRID definitions in use, for example by selecting a record