FIG Working Week 2000, 21-26 May, Prague

Reference Frames in Practice: The Role of Professional, Scientific, Standards and Commercial Organisations

by Paul Cross, Matt Higgins and Roger Lott

Key words: reference frame, co-ordinate system, datum, co-ordinate transformation, satellite positioning system. 


It is well known that the current, and growing, trend towards use of satellite positioning systems and global satellite mapping systems to produce position-based products in a global reference frame can introduce serious practical difficulties if the results need to be related to older maps and/or digital data. Special problems arise, for instance, in the fields of navigation, map revision, cadastral surveying and geomatics operations to support hydrocarbon exploration and production.

The difficulty fundamentally arises because of the need to transform the data into the (usually local) co-ordinate systems used to describe the older data (or vice-versa). In principle co-ordinate transformations are a straightforward mathematical procedures but in practice they can cause serious problems because:

  • not all of those who need to undertake this work have a sufficiently strong (or sufficiently up to date) education in basic geodesy, and/or
  • the distortions and inconsistencies of the local datum are not sufficiently well known, and/or
  • the numerical information needed (including transformation parameters) is not readily available, and/or
  • the language use to describe the various parameters and physical quantities is not uniform.

This paper reviews the work of a number of international organisations in solving some or all of these problems. Special emphasis is placed on the following.

  • Scientific bodies such as the International Association of Geodesy (IAG) and the International Astronomic Union (IAU) and some of their sub groups and special commissions (e.g. Commission X of IAG and the IERS).
  • The International Federation of Surveyors (FIG) and its many Commissions and Working Groups - including WG5.5 - Reference Frames in Practice in which all three authors participate.
  • Various International Standards organisations and their sub-committees (e.g. ISO TC211) and consortia of commercial companies concerned primarily with formats for data exchange.

It is concluded that there is currently insufficient co-ordination between the work of the many groups with interests in this field - but, despite this, progress is slowly being made, especially in the collection and distribution of information, education of users and adoption of a common set of definitions.

Professor Paul Cross
Department of Geomatic Engineering
University College London
Gower Street
London, WC1E 6BT

Dr Matt Higgins
Department of Natural Resources
Locked Bag 40

Roger Lott
BP Amoco Group
Chertsey Road
TW16 7LN

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