|Jones, L D. 2015. Ground-based geomatic surveys at the BGS - a manual for basic data collection & processing (2015). British Geological Survey Internal Report, OR/15/057.|
Geomatics is the discipline of electronically gathering, storing, processing and delivering spatially related digital information. This broad term applies both to 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.
The British Geological Survey (BGS) has been using ground-based geomatics techniques for a variety of geoscientific applications since 2000. The importance of geomatics data acquisition and monitoring capabilities to the BGS has been highlighted in particular, but not exclusively, with respect to geoscience priorities linked to Integrated Environmental Modelling (BGS– Emerging strategy 2014-2020, Peach, 2012) and the need for enabling technologies to improve capability in 3D data capture, analysis, modelling and visualisation (BGS Top Geoscience Priorities, Peach, et. al., 2012). BGS will continue to harness new technology to instrument the earth (Gateway to the Earth, Patterson & Ludden, 2014).
The discipline of geomatics continues to be one of the fastest expanding global markets. Ground- based geomatics is driven by technology and, at present, there is a huge demand for land, hydrographic and engineering surveyors who are able to fully utilise this technology. This is due to a high media profile, the changing nature of mapping and spatial data management worldwide and the growth in EU and national governments' spatial data agendas and legislation. As the underpinning information provider of the land and property lifecycle, geomatics is of fundamental importance to society.
The most common geomatics application in BGS uses a mobile Light Detection and Ranging (LiDAR) scanner, a Global Navigation Satellite System (GNSS) and a Geographic Information System (GIS) in order to obtain a terrestrial version of an airborne LiDAR survey and create a 3D model. Combining a terrestrial LiDAR scanner with a high-resolution digital camera and a high-precision differential GNSS enables coloured point-clouds, textured triangulated surfaces, or orthophotos with depth information to be accurately geo-referenced and captured. The relative distance, elevation angle and azimuthal angle between the laser and the subject are measured in each scan and, once processed, a 3D surface model can be generated. From the 3D models created a variety of products have been derived including digital elevation models (DEM), virtual outcrop models (VOM), cross-sections, area and volume calculations, 3D photo-realistic video ‘fly-throughs’, discontinuity maps, stratigraphic facies profiles, attributed 3D reservoir models, fossil assemblage maps, surface deformation feature recognition layers, soil erosion maps, cave surveys and change models. BGS also has the ability to produce high-resolution 3D photo-realistic scans of fossils in order to preserve the fossil record. Terrestrial LiDAR Scanning (TLS) allows geological outcrops to be digitally captured with unprecedented resolution and accuracy (Buckley et. al., 2007).
The BGS geomatics capabilities have been utilised in a variety of scientific studies such as the monitoring of actively growing volcanic lava domes and rapidly retreating glaciers; coastal erosion and platform evolution; inland and coastal landslide modelling; mapping of geological structures and fault boundaries; rock stability and subsidence feature analysis; and geo- conservation (Jones, 2014b). These capabilities can be utilised alongside airborne LiDAR and other Remote Sensing techniques in order to provide a range of complimentary applications.
Outside the BGS Terrestrial LiDAR Systems are used for close-range, high-accuracy applications such as bridge and dam monitoring, architectural restoration, crime and accident scene analysis, landslide and erosion mapping, forest canopy and biomass measurements, mobile mapping systems, adaptive cruise control systems, manufacturing, and military applications.
Utilisation of the BGS geomatics capability has steadily increased since its initial introduction in 2000. However, operational and data-handling procedures are still undertaken on a relatively ‘informal’ or unstructured basis, and staff expertise in these techniques remains limited. In addition, developments in modern laser technology have hugely increased the amount of spatial data acquisition. This has repercussions for increased computing power and state-of-the-art software for processing this data, and the need to address the important issues of storage, archiving, access and delivery with respect to these important and unique digital datasets on a corporate basis.
This manual has been produced in order to enhance the ‘Ground-based Geomatics’ basic training course, for staff that require the use of Terrestrial Laser Scanning (TLS) and Global Navigation Satellite System (GNSS) equipment in order to carry out ground-based geomatic surveys. It gives an overview of the equipment used in these techniques, a brief outline into the basic principles of GNSS and TLS techniques, and provides a basic step-by-step guide to their initial set-up procedures.
This manual also provides an in-depth, comprehensive, guide in dealing with the data that is generated by these systems. Step-by-step procedures are given for downloading the data from all the systems, including any peripherals required, a basic guide to the processing of this downloaded data is also provided, along with a discussion about the various software programmes available in BGS for data visualisation and interrogation.
NOTE: This is a Guide to the most commonly used applications only.