Ground-based and near-Earth geomatic surveys

Geomatics is the discipline of electronically gathering, storing, processing and delivering spatially related digital information. This broad term applies to both science and technology, and integrates the more specific disciplines and technologies of geodesy, surveying, mapping, positioning, navigation, cartography, remote sensing, photogrammetry and geographic information systems (GIS).

BGS has pioneered the use of ground-based (terrestrial) and near-Earth techniques for a variety of geoscientific applications since 1999. These have been used on a variety of projects such as:

• monitoring actively growing volcanic lava domes
• monitoring rapidly retreating glaciers
• coastal erosion and platform evolution
• inland and coastal landslide modelling
• mapping of geological structures and fault boundaries
• rock stability
• subsidence feature analysis
• creating surrogate outcrop models for oil field reservoir rocks
• geo-conservation projects, such as archiving and analysis of important outcrops, quarries and other temporary exposures

In fact, BGS has carried out over 300 surveys at more than 150 sites, both in the UK and overseas.

Quick links

• Terrestrial LiDAR Scanning
• Unmanned Aerial Systems (UAS)
• Mobile Mapping Solution
• Tracking glaciers’ retreat
• Monitoring shifting coastlines
• Measuring active volcanos
• Case studies & downloadable reports
• TLS locations
• Publications

Terrestrial LiDAR scanning

As a tool of modern geoscience, the use of terrestrial LiDAR scanning allows unprecedented resolution and accuracy.

The BGS uses Riegl and Faro terrestrial light detection and ranging (LiDAR) scanners because of their flexibility, range and portability. We have a very long-range scanner that can make measurements at distances of over 2000 m, a medium-range scanner that can make accurate measurements at distances of up to 800 m and a high-speed short-range (300 m) scanner that can take measurements at a rate of 972000 points/second with an accuracy of ±3 mm.

Our newest model is the Riegl VZ-1000, which can scan up to 1400 m with an accuracy of ± 8mm and a measurement rate of 62000 points/second. A high-resolution digital camera coupled with a Leica global navigation satellite system (GNSS) enables coloured point-clouds, textured triangulated surfaces or orthophotos, with intensity and depth information, to be captured, accurately geo-referenced and processed.

Modern terrestrial LiDAR scanners (TLS) have significantly increased the level of resolution and accuracy achievable, and the speed of data acquisition. The ability to capture and measure changes in geological features with time by repeat surveys has revolutionised ground-based geomatic research.

Unpiloted aerial systems (UAS)

Structure from motion photogrammetry (SfM) has emerged as an alternative viable technology, whether deployed on an unpiloted aerial system (UAS) or otherwise. It is lighter, more compact, cheaper to buy and repair, and has lower power requirements than TLS.

BGS has six multi-rotor UAS, which it uses to collect data for ground surface and geological investigations. UAS are becoming increasingly common for civilian use, with the Chinese manufacturer DJI and the US company Parrot dominating the market. They are used in such fields as:

• geology
• geomorphology
• surveillance
• film making
• scientific research
• surveying
• disaster relief
• law enforcement
• archaeology
• forestry and agriculture
• recreation

Like many other organisations, BGS is able to utilise the usability and portability of these aircraft to create photogrammetric images and point clouds using SfM techniques at a fraction of the cost of using a system mounted on an aeroplane. The resultant data, though not as accurate as that obtained from TLS, should still be considered more than adequate for most uses, and gives the ability to create both 2D and 3D full-colour models.

BGS uses drones to gain a perspective of the Earth that is simply not possible with instruments that are based on the ground. For more information please see our drone research page.

Mobile mapping solution

BGS was one of the first companies in the UK to purchase the Leica Pegasus Backpack, a wearable reality-capture sensor platform. The backpack combines five 4 MP cameras, offering a fully calibrated 360° × 200° view, with two 16-channel LiDAR profilers, capable of scanning 600 000 points/second at a range of 50 m, and a triple-band GNSS and inertial measurement unit (IMU), capable of a positional accuracy of 20 mm, in an ultra-light carbon-fibre chassis weighing 13 kg.

The Pegasus Backpack offers great speed and portability advantages over existing terrestrial LiDAR systems, which can weigh in excess of 30 kg and are extremely bulky to carry. This enables us to carry out 3D mapping of long coastal (or inland) sections, landslides and other unstable surfaces, ice sheets and glaciers, railway lines, roads and other linear features. We can also use the backpack to carry out building information modelling (BIM) using both imagery and point-cloud data to document outdoor, indoor and even underground areas.

Disaster responders will be able to capture data in 3D, on foot, in danger zone areas. Simultaneous localisation and mapping (SLAM) technology and a high-precision IMU ensure the achievement of accurate positioning, even during GNSS outages. An external light-source makes precise scanning of tunnels and cave systems possible. The backpack can also be vehicle mounted for mobile mapping, or pole mounted for lowering into voids or sinkholes. This system allows for faster capture of critical data, leading to better-informed decisions, on-site if necessary.

Tracking glaciers’ retreat

By using a combination of repeat TLS surveys, on-ice based GNSS and ground penetrating radar (GPR), we have been able to see the full picture of glacial retreat for the first time. This work has shown that the margin of the Falljökull glacier, in south-east Iceland, has ceased moving and is now undergoing stagnation. However, field and photographic evidence show that the icefall remains active, feeding ice from the accumulation zone on Öraefajökull to the lower reaches of the glacier. To accommodate this continued forward motion, the upper section of the glacier below the icefall is undergoing intense deformation (folding and thrusting) and, as a result, is being thrust over the lower, immobile section of Falljökull.

This type of behavior has never been described before and could have implications for how other steep, mountain glaciers around the world are responding to changes in the climate.

Monitoring shifting coastlines

We use our laser systems to monitor actively eroding sections of coast around England. The techniques we have developed are ideal for this application, as TLS is particularly suited to measuring vertical cliff sections. Measurements from a plane or satellite measure only the top edge of the cliff, whilst measuring them in the field is often very dangerous. Our technique enables us to take measurements of changes in the whole cliff section, from a safe distance, which can be used to model how internal processes within the cliff slope affect coastal erosion.

Our work at Aldbrough, in North Yorkshire, has shown that the cliff is disappearing at a rate of 3 m a year. This erosion is caused by both landslides and the direct action of the sea crashing against it.

Measuring active volcanoes

There can be few more hazardous situations than that of monitoring a volcanic andesite lava dome for signs of an impending collapse. Partial collapse of a lava dome generates hot, fast-moving, pyroclastic density currents. Monitoring in such circumstances requires measurements to be taken from a distance that minimises the threat from eruption and from asphyxiation by volcanic gases. The method also needs to be rapid, to minimise the time spent by the monitoring team in the hazardous zone.

We have used TLS techniques to monitor the growth of the lava dome on the Soufrière Hills Volcano, on the Caribbean island of Montserrat. In May 2006, our measurements helped to identify the changes in lava dome growth rate that directly preceded a total lava dome collapse.

Case studies and downloadable reports

Here five case studies utilising various different pieces of ground-based geomatic equipment, and their applications are presented:

• Aldborough, Yorkshire
• Hellfire Caves, High Wycombe
• Hollin Hill, Yorkshire
• Permian sandstone
• Virkisjökull Glacier Observatory, Iceland

TLS locations

Terrestrial LiDAR scanning has been carried out on over 170 different sites, both in the UK and overseas. You can download more information about the TLS locations.

Publications