History of the EPSG Dataset
Today, the IOGP EPSG Dataset is used across virtually all geospatial domains as the global de facto standard for very complete, publicly available, reliable geodetic definitions. EPSG codes are used in practically all commerical and open GIS software, libraries, and as geospatial metadata to identify spatial 3D, horizontal and vertical coordinate reference systems and transformation of coordinates between these systems.
Despite suggestions by its origin in the petroleum industry and maintenance by the IOGP (International Association of Oil & Gas Producers), EPSG codes and definitions are used in practice by local and national geodetic and mapping agencies, land and marine surveyors, in planning, construction and development, software, etc. For decades already, usage of the EPSG data has not been exclusive to petroleum exploration and production activities, but is used in all kinds of applications such as for web mapping, transport, digital twins, and renewables including wind and solar. The letters "EPSG" are a brand name and no longer refer to petroleum, as described in the following overview of the history of the EPSG Dataset.
The beginnings
In the mid 1980s, Jacques Guilleminot, the Chief Surveyor for Elf Aquitaine, suggested a meeting of the Geomatics leaders of several European multinational oil majors to discuss issues of mutual interest. A meeting was convened in Paris in early 1985 attended by representatives of eight companies[1] all of which had operations in several countries, in total spanning most of the world.
It was agreed that a significant problem for all was integrity of geodetic definitions in their computer systems, and that there would be great benefit to each company's knowledge if this data were shared.
The meeting participants agreed to exchange their holdings of geodetic data definitions 'without delay'. So the European Petroleum Survey Group, commonly abbreviated to "EPSG", was founded. The sharing of coordinate reference system definitions was the first collaborative project of the Group.
Initially the shared geodetic data was compared internally within the members of the Group. A master copy of the data set was maintained by Elf in Pau. Majority voting was used to resolve data discrepancies, not necessarily a robust procedure because the data sources may not have been independent. Individual members of the group established their own internal databases containing the subset of shared data of particular interest to themselves. In the late 1980s and early 1990s a geodesy working group was formed to create and maintain a relational database holding the geodetic data. The EPSG Geodetic Parameter Dataset (to give it its full name) was born.
In October 1990 the Petrotechnical Open Software Corporation (POSC) was founded, staffed mainly by secondees from the founding companies[2]. Work began on a data model for subsurface data. POSC was aware of the EPSG Dataset and asked whether its coordinate reference system data model could be used within the POSC model. The intention was for the POSC model to be open. The EPSG agreed that its data model and the shared Dataset could be adopted by POSC.
The intention of POSC to publish the data caused EPSG to ask whether it should publish the Dataset itself. After a data review and rigorous verification against official definitions, the first public version of the EPSG Dataset was made in late 1993, with the same data also published by POSC in June 1994. The initial dataset consisted of just over 500 coordinate reference system definitions. To ensure data integrity the content, which comes mainly from national mapping agencies, is verified against authoritative information before it is published.
In 2005 the European Petroleum Survey Group was disbanded and reformed as the Geomatics Committee of IOGP with maintenance responsibilities for the Dataset given to the IOGP Geodesy Subcommittee. Because it was already so well-established, the acronym EPSG was retained as the brand name for the Dataset, without any meaning to the letters.
Evolution to a de facto standard
A significant increase in external interest in the EPSG Dataset occurred in 1995 when the EPSG codes were adopted for use in the GeoTIFF v1.0 format for georeferenced imagery, and later when the then Open GIS Consortium (now the Open Geospatial Consortium, OGC) adopted the EPSG Dataset as the core of its CRS definitions.
A consequence of these agreements was a commitment that the content of the EPSG Dataset would include data that was not necessarily of interest to the Dataset's sponsors. What did the sponsors get from this? They gained greater adoption of the Dataset content, particularly from the providers of spatial applications that they used.
From its early distribution mechanism in a proprietary relational database, SQL scripts were added in 2004 and an online registry from 2008. The data model was upgraded to be compliant with ISO 19111 in 2001, with further upgrades in 2007 and 2020 and minor update in 2023, tracking revisions to ISO 19111.
Since 1993 the content of the EPSG dataset has grown continuously, and thirty years later it contains over 7000 CRS definitions (including almost 2500 map projections), as well as over 2500 coordinate transformations. Together with supporting elements, there are now 20,000 items defined in the Dataset.
Used by all IOGP members and their spatial application software providers, as well as numerous other users, the EPSG Dataset is the de facto global standard for coordinate reference system descriptions for use in spatial software. Its relationship to other registries is summarised in the ISO/OGC/IOGP Guide to CRS registries.
Recognition at the 2008 EAGE Conference
The work of the IOGP geodesy subcommittee members was recognized by EAGE in 2008 with words that hold true “in recognition of their dedicated work on the creation, development and public release of the EPSG database… the only accessible and authoritative source of information on geodetic datums and projections in use round the world. It is vital to all aspects of geoscientific work”.
