Metrology for long distance surveying

Short Name: Surveying, Project Number: SIB60
Rock slide sign

Large measurements over long distances: Accurate surveying for science and engineering

Large construction projects such as building tunnels and bridges must often be delivered with millimetre accuracy. Similarly, mountain towns, mines, and nuclear sites need to be closely monitored for tiny movements that may lead to landslides or sinkholes. Long distance measurements are made using both global navigation satellite systems (GNSS) and electronic distance measuring (EDM) Instruments, with European products contributing over €107M to the EU’s economy annually.


EDMs use laser-based ranging systems calibrated against baseline networks consisting of a series of well-defined pillars, but temperature and air turbulence change the air’s refractive index, reducing calibration and measurement accuracy. GNSS is influenced by high atmospheric environmental factors as well as by electromagnetic near-field effects. To improve long distance measurement precision, better links to the SI definition of the metre with sub-millimetre uncertainties are needed.


This project developed new robust calibration and transfer standards with compensation for refractive index changes, and made recommendations to improve measurement practices.


The Project:

  • Developed the TeleYAG, which uses interferometry to perform in-situ compensation for refraction variations, achieving sub-millimetre accuracy over distances of up to a kilometre, and creating traceability to the SI meter without reference baselines or environmental sensors
  • Developed and validated the single laser TeleDiode system capable of achieving a measurement resolution below 5 μm over 1 km. This system has the potential to create a cost effective and robust standard for transferring accuracy between base stations and user instruments
  • Extended the distance measurement capability of highly accurate multi-wavelength femtosecond ranging from 15 cm to 50 m, using femtosecond combs, which create a direct link between short femtosecond frequencies and longer frequencies for metre-scale measurements
  • Investigated sources of inaccuracy for GNSS systems, associated with satellite positioning, signal propagation and measurement antenna position, and suggested improvements.


This project developed solutions for high accuracy long distance measurement enabling better traceability for surveying, geodesy and earth sciences. The TeleYAG and TeleDiode now serve as standards for long distance measurements, with the TeleDiode being commercialised and having additional potential for use in large volume measurements, building on developments from the EMRP LUMINAR (IND53) project. Best practice for both GNSS and EDM surveying instruments was publicised by the German Society for Geodesy, Geoinformation and Land Management, in both German and English to promote uptake by the international surveying community.


Increased interaction between the metrology and geodesy communities, as a result of this project, has enabled a member of the consortium to join and chair an influential geodesy organisation, the International Earth Rotation and Reference Systems Service Working Group on Site Survey and Co-location.

Project website
SI-Traceable High-Accuracy EDM based on Multi-Wavelength Interferometry

Proceedings of the third Joint International Symposium on Deformation Monitoring

Spectroscopic Inline Thermometry

Proceedings of the third Joint International Symposium on Deformation Monitoring

Towards Kilometric Distance Measurements with Air Refractive Index Compensation

Proceedings of the third Joint International Symposium on Deformation Monitoring

JRP SIB60 “Metrology for Long Distance Surveying”-a concise survey on major project results

Proceedings of the third Joint International Symposium on Deformation Monitoring

Global Geodetic Observing System (GGOS) Requirements for Core Sites

CDDIS: NASA's Archive of Space Geodesy Data

Improving the traceability chain in geodetic length measurement by the new robust interferometer TeleYAG

Proceedings 19th International Research/Expert Conference "Trends in the Development of Machinery and Associated Technology"

Repetition rate multiplication of a femtosecond frequency comb

Proceddings SPIE 9450, Photonics, Devices and Systems VI

Die neue Neubiberger Pfeilerstrecke

Zeitschrift für Vermessungswesen: ZfV

Length characterization of a piezoelectric actuator travel with a mode-locked femtosecond laser

Proceedings SPIE 9525, Optical Measurement Systems for Industrial Inspection IX

Other Participants
National Scientific Centre Institute of Metrology (Ukraine)