Abstract Digital survey methods, including terrestrial laser scanning (LIDAR) and differential GPS, allow geological and topographic data from outcrops to be recorded very rapidly, in 3D, at detailed resolutions and with high spatial precision. Geological interpretations of outcrop datasets (e.g., fault or bedding traces) can be extended into the subsurface using geometric, probabilistic, or deterministic methods. Geometric methods based on interpolation and extrapolation of observed surfaces and surface traces are generally associated with high uncertainty. This can be reduced in areas of highly irregular topography. Another approach is to use geological heuristics to constrain the subsurface interpretation. This approach can help to limit the number of possible interpretations when creating multiple realizations. Deterministic methods encompass both invasive and non-invasive approaches. Invasive methods include mining and quarrying, as well as small-scale excavation of unconsolidated sediments. Behind-the-outcrop boreholes are only slightly invasive, and can provide very useful constraint of the subsurface. In contrast, geophysical methods such as near-surface seismics and ground penetrating radar (GPR) allow indirect imaging of the subsurface and are non-invasive. Excellent coastal exposures of Namurian turbidites near the Bridge of Ross in County Clare, western Ireland, provide a case study in which several different types of digital outcrop data are combined and co-visualized in a 3D model. In vertical sections on opposite sides of the outcrop a small-scale turbidite channel is marked by an erosional base and inclined interbedded sandstones and mud-clast conglomerates. The observed channel margins can be traced through the subsurface using 3D GPR.

Abstract Rapidly developing methods of digital acquisition, visualization and analysis allow highly detailed outcrop models to be constructed, and used as analogues to provide quantitative information about sedimentological and structural architectures from reservoir to subseismic scales of observation. Terrestrial laser-scanning (lidar) and high precision Real-Time Kinematic GPS are key survey technologies for data acquisition. 3D visualization facilities are used when analysing the outcrop data. Analysis of laser-scan data involves picking of the point-cloud to derive interpolated stratigraphic and structural surfaces. The resultant data can be used as input for object-based models, or can be cellularized and upscaled for use in grid-based reservoir modelling. Outcrop data can also be used to calibrate numerical models of geological processes such as the development and growth of folds, and the initiation and propagation of fractures.

Abstract Traditional methods of geological mapping were developed within the inherent constraints imposed by paper-based publishing. These methods are still dominant in the earth sciences, despite recent advances in digital technology in a range of fields, including global-positioning systems, geographical information systems (GIS), 3-D computer visualization, portable computer devices, knowledge engineering and artificial intelligence. Digital geological mapping has the potential to overcome some serious limitations of paper-based maps. Although geological maps are usually highly interpretive, traditional maps show little of the raw field data collected or the reasoning used during interpretation. In geological mapping, interpretation typically relies on the prior experience and prior knowledge of the mapper, but this input is rarely published explicitly with the final printed map. Digital mapping techniques open up new possibilities for publishing maps digitally in a GIS format, together with spatially referenced raw field data, field photographs, explanation of the interpretation process and background information relevant to the map area. Having field data in a digital form allows the use of interpolation methods based on fuzzy logic to quantify some types of uncertainty associated with subsurface interpretation, and the use of this uncertainty to evaluate the validity of competing interpretations.