Data Model Changes


Data Model Changes


Following the publication of the revised ISO 19111:2019 data model, IOGP is in the process of upgrading the EPSG data model. The changes to the data model being applied to the v10.0 EPSG Dataset and Dataset available via the Beta Site are:

 - Identification of dynamic datums and of CRSs based on these. For datums and CRSs affected by this change, there will be no changes to existing EPSG codes.



Details of data model changes to relational tables
Changes to relational tables with details listed by table

See here for changes to GML Schema.

- Addition of a new construct of ‘datum ensemble’. A datum ensemble groups together successive realizations of a datum as one. Some CRSs will be associated with a datum ensemble rather than a single datum. These will include the generic WGS 84 CRSs (EPSG CRS codes 4326 [geographic 2D], 4979 [geographic 3D] and 4978 [geocentric]). Existing EPSG codes will be unchanged.

- Addition of a new CRS subtype ‘derived projected’. The term is from the ISO model and is consistent with other terms in the model, but is a misnomer. It is a CRS which is based upon an existing projected CRS, so ‘derived from projected’ would be a more accurate description. Many seismic bin grids are defined relative to a projected CRS – others are defined independently and later referenced to a projected CRS. Examples of both approaches will be included in the upgraded dataset.

- Some CRS, datum or coordinate operation entities will be associated with multiple ‘usages’ – scope/extent (area) pairings.