Data Model
Data Model Changes |
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Following the publication of the revised ISO 19111:2019 data model, IOGP has upgraded the EPSG data model. The changes to the data model which apply from version 10.0 of the EPSG Dataset 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. - 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. |
Download: Details of data model changes to relational tables See here for changes to GML Schema. |
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- 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. Further details of the data model mapping from the previous implementation to the current implementation may be accessed through the panel to the right. |
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