Combining laser-scanning, RTK GPS and 3D visualisation: Application of optical 3D measurement in geological exploration

Geoscientific data is inherently three-dimensional in nature. Despite this, many field geo-scientists still rely on traditional paper-based mapping methodologies in which three-dimensional real-world data are simplified and displayed in 2D. In recent years, petroleum geologists have developed sophisticated methods using high resolution 3D seismic survey data to build detailed 3D models of sub-surface geological architectures for use in hydrocarbon exploration and production. Modern optical 3D measurement and visualisation techniques now make it possible to analyse rock outcrops exposed at the surface using an approach that is conceptually comparable to that used in petroleum exploration. The high accuracy and spatial resolution provided by terrestrial laser-scanners, combined with high resolution digital photography and digital mapping methodologies, make it possible to create photo-realistic virtual geological outcrops. These are geospatially and geometrically precise models of real-world surface exposures which allow the geo-scientist to take a precise image of the outcrop back to the laboratory where it can be visualised, analysed and interpreted. Real-Time Kinematic GPS, with single centimetre spatial precision, is used to ensure that each virtual model is geospatially positioned correctly, and allows several overlapping models to be stitched together as seamlessly as possible. The resulting virtual outcrops are analysed using a customised 3D visualisation software tool-box that allows the user to interact directly with the virtual outcrop either using full colour auto-stereoscopic 3D screens or fully immersive stereo projection. From the point cloud viewed in virtual reality, the geo-scientist can pick surfaces such as bedding, faults and 3D fracture networks and sedimentary architectures. The application of a combination of digital mapping, optical 3D measurement and 3D visualisation techniques provides geo-scientists with an exciting and powerful new set of tools that can be applied to a broad range of geological problems.