Geodetic Framework – Geodetic Authority

Geodetic Authority

When evaluating pre-defined geodetic parameters (recognized by the software applications) it is necessary to have a benchmark against which a comparison of values can be made.  This requires using a recognized geodetic authority.  Fortunately, such an authority is available to the industry.  Furthermore, the authority is free and is independently maintained and published by IOGP -Geomatics Sub-committee.  The authority is known as EPSG geodetic parameter registry and is available in several different formats to cater for software developers and casual users alike.  EPSG refers to European Petroleum Surveyors Group and was the predecessor to OGP and IOGP.  The name was retained as it was commonly used to refer to the library prior to OGP being formed.

EPSG geodetic parameter registry is a collection of all recognized geodetic parameters required to unambiguously define a coordinate reference system or coordinate transformation in its entirety.  As such its definitions include all fundamental building blocks including Ellipsoids, Prime Meridians, Units of Measure, Coordinate Systems and Coordinate Axes to name a few.  Every component recognized by the registry is assigned a reference number to uniquely identify that element.  These are known as the EPSG codes and adopting their use in referencing CRS definitions contained within software applications is highly recommended.   The codes have also been adopted by some exploration companies to form part of the naming syntax applied to CRS’ used by those companies.

User-defined coordinate reference systems must be formally documented.  For example, the definition of a new 2D projected CRS may be created for a new ventures area or for an area where data sets are merged over a regional extent.   In either case the new system parameters must be captured and the CRS assigned its own ‘EPSG’ code using a number outside the protected range of codes identified by IOGP.


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