Geodetic reference frames – Why do we need them?

Geodetic reference frames – Why do we need them?


A geodetic reference frame provides the foundation for determining positions on Earth and in space, as well as for reliably quantifying our planet’s changes due to geodynamic processes and ongoing climate change. The ITRF ensures a uniform basis to tackle current and future challenges, including a wide range of location-based applications (navigation, traffic and fleet management, transport logistics, control of industrial and agriculture machinery, autonomous driving, …) that now deeply pervade our daily life. A uniform global and long-term stable reference frame is also required for understanding the dynamics of our planet, for monitoring climate change phenomena and for operating early-warning systems to protect against natural hazards. The standard reference frame recommended by a number of international scientific organizations, including the International Union of Geodesy and Geophysics (IUGG) and the International Association of Geodesy (IAG) for Earth science, satellite navigation and positioning applications is the International Terrestrial Reference Frame (ITRF).


Four space geodetic techniques are currently used for the ITRF computation:  Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), Global Navigation Satellite Systems (GNSS), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS). These four observation techniques now provide observations over 25 to 40 years. The analysis of the VLBI, SLR, GNSS and DORIS observations over this long-time span is a tremendous international effort, which is done by four scientific services (IVS, ILRS, IGS and IDS) of the IAG. The three ITRS Combination Centers of the IERS, namely the Institute national de l’information géographique et forestière (IGN) in Paris, the Deutsches Geodätisches Forschungsinstitut of the Technical University of Munich (DGFI-TUM), and the Jet Propulsion Laboratory (JPL) of NASA in Pasadena, are responsible for the combination of the data provided by the four technique-specific IAG Services. The most recent realization of the International Terrestrial Reference System (ITRS), the ITRF2020, was published on 15 April 2022 (https://itrf.ign.fr/en/solutions/ITRF2020).

Space geodetic techniques VLBI, SLR, GNSS and DORIS and their observation time span used for the realization of the geodetic reference system (Source: DGFI-TUM)


Recently the IAG’s Global Geodetic Observing System (GGOS) produced a short film “Terrestrial Reference Frames – Connecting the World through Geodesy”. This video illustrates the importance of geodetic terrestrial reference frames for science and society. It shows how a terrestrial reference frame is defined and realized, and how the ITRF helps us understand our dynamic planet.


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More information:

Detlef is a senior scientist at the Deutsches Geodätisches Forschungsinstitut of the Technical University of Munich (DGFI-TUM). He is head of the Focus Area "Reference Systems" and his research focuses on the analysis of space geodetic observations for the realization of reference systems and the determination of Earth system parameters. He is director of the GGOS (Global Geodetic Observing System) Office of Products and Standards.

Dr. Laura Sánchez is a research scientist at the Deutsches Geodätisches Forschungsinstitut (DGFI-TUM) of the Technische Universität München, Germany. She holds a doctor degree in Geodesy from the Technische Universität Dresden, Germany. Her research interests include vertical datum unification, global height reference systems, GNSS-based regional reference frames, and surface kinematics monitoring. She is the current president of the Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG).

Martin works at the Federal Office of Metrology and Surveying (BEV) in Vienna, Austria. In addition to his GNSS (Global Navigation Satellite Systems) activities in one of the EUREF (Regional Reference Frame IAG Sub-Commission for Europe) analysis and data centers, he acts as the director of the GGOS (Global Geodetic Observing System) Coordination Office to ensures optimal coordination of the activities of the various GGOS components and to manage GGOS outreach activities.

Rebekka is a researcher at Lantmäteriet (The Swedish Mapping, Cadastral and Land Registration Authority). She is working on glacial isostatic adjustment (GIA) modelling with a focus on stress field changes and model development, and is involved in the development of a European velocity model as part of EUREF (Regional Reference Frame IAG Sub-Commission for Europe). Rebekka is also the chair of a IAG (International Association of Geodesy) Joint Study Group on GIA. She received her PhD in 2013 from the University of Calgary.


  1. Very nice and useful video! Thanks so much

  2. Much needed video, we need to keep posting in brief like this one. The topic of reference frames is still challenging to many especially the dynamic versions.


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