Overview
EN ISO 19168-2:2022 - "Geographic information - Geospatial API for features - Part 2: Coordinate Reference Systems by Reference" specifies an extension to the Geospatial API for Features (ISO 19168-1). It defines how a server advertises and uses Coordinate Reference Systems (CRS) by reference (using URIs) so geometry-valued properties and spatial queries can be expressed and returned in one of a list of supported CRSs. The standard was prepared from the OGC API - Features Part 2 specification and adopted by CEN/ISO for consistent, interoperable web APIs for spatial data.
Key topics and requirements
- CRS by reference: Each supported CRS is identified by a uniform resource identifier (URI); servers must expose these identifiers.
- Discovery: For each offered feature collection, servers advertise the list of supported CRS identifiers (discovery of available CRSs per collection).
- Coordinate access: Clients can request geometry-valued feature properties returned in one of the supported CRSs.
- Spatial queries: Features may be queried using bounding boxes specified in any supported CRS (parameters such as bbox-crs are defined).
- Server declaration: Servers declare which CRS is used to present feature resources and provide CRS metadata independent of feature encoding.
- Implementation considerations: Includes storage CRS, global lists of CRS identifiers, query parameters (e.g., crs, bbox-crs), and output format considerations.
- Conformance: Defines a requirements class - Coordinate Reference Systems by Reference - to guide implementers and testing (abstract test suite provided).
Practical applications
- Enables consistent, interoperable delivery of geospatial features across web APIs where clients and servers may use different CRSs.
- Useful for:
- GIS platform and web map API developers implementing OGC/ISO-compliant feature services.
- Spatial data providers and national mapping agencies that must publish datasets in multiple CRSs.
- Application developers who consume spatial feature collections and require on-the-fly CRS transformations for display, analysis or bounding-box queries.
- Benefits include improved client-server interoperability, reduced need for client-side CRS guessing, and clearer metadata about coordinate systems used.
Related standards
- ISO 19168-1:2020 - Geospatial API for Features - Part 1: Core (base API behaviour and resource model).
- ISO 19111:2019 - Spatial referencing by coordinates (definitions related to CRS and coordinate systems).
- OGC API - Features family (original OGC specifications from which this ISO part is derived).
Keywords: EN ISO 19168-2:2022, Geospatial API for features, Coordinate Reference Systems by Reference, CRS URI, bbox-crs, crs parameter, OGC API Features, ISO 19168 series, spatial web API, feature collection.