GeoJSON is a widely used format for encoding geographic data especially in web environments. It is based on JSON and designed to represent simple geographical features and their attributes. However, GeoJSON has long had some drawbacks that presented some pitfalls for users.
Now, the OGC1 has released a newstandard called “OGC Features and Geometries JSON” or “JSON-FG”, for short. What does JSON-FG add? There are three mandatory extensions to GeoJSON:
- ability to use CRSs2 other than WGS 1984 with lon-lat axis order
- ability to encode temporal characteristics of features
- a statement identifying the JSON-FG conformance classes supported by a JSON-FG feature collection, feature, or geometry
… and these optional extensions:
- support for circular arcs, compound curves, and curve polygons as geometry types
- support for solids and prisms as geometry types
- support for measure values in coordinates
- ability to declare the type and schema of a feature
JSON-FG is a superset of GeoJSON. Thus, legacy tools will be able to read JSON-FG without modification (but, of course, not make use of the new features). From the announcement:
Additional information not specified in the GeoJSON RFC is mainly encoded in additional members of the GeoJSON objects. These additional members use keys that do not conflict with existing GeoJSON keys, enabling existing and future GeoJSON clients to continue parsing and understanding GeoJSON content successfully. Clients that support JSON-FG can additionally parse and interpret the extended members.
More information can be found in the announcement and on the standard’s page.