gpkgspatialrefsys

The gpkg_spatial_ref_sys table is a core component of the GeoPackage specification. It stores coordinate reference system (CRS) definitions used by vector features and tiled content within a GeoPackage, enabling consistent interpretation and transformation of geometry coordinates across layers.

The table schema comprises six columns: srs_id (INTEGER PRIMARY KEY), srs_name (TEXT NOT NULL), organization (TEXT NOT NULL), organization_coordsys_id (INTEGER NOT NULL), definition (TEXT NOT NULL), description (TEXT). The srs_id serves as a unique identifier and is referenced by other spatial tables via their srs_id columns. The definition column holds the CRS in a well-known text (WKT) representation. The description field provides a human-readable note.

The organization and organization_coordsys_id pair typically encodes a CRS using a registry such as EPSG (for example, EPSG with code 4326). The combination of organization and organization_coordsys_id should be unique within the database, matching the corresponding WKT in definition.

Use and interoperability: GeoPackages commonly include entries for widely used CRSs like EPSG:4326 (WGS 84) and EPSG:3857 (Web Mercator). Client software reads gpkg_spatial_ref_sys to interpret coordinate values and, where supported, perform reprojection.

Extensibility and validation: The table can be extended with additional CRS definitions as needed. GeoPackages should validate that srs_id values are unique and that the WKT in definition corresponds to the CRS described by organization and organization_coordsys_id.