Hand scanners are compact, lightweight, and capable of generating 3-D digital models. Although they do not compare to conventional methods (terrestrial laser scanning and photogrammetry) in terms of coverage, resolution, and accuracy, they offer increased mobility, speed, and real-time processing capabilities in the field. This study investigates the use of hand scanners for real-time, 3-D digital outcrop modeling to augment geological field mapping campaigns and highlights the advantages and the limitations. The utility of incorporating hand scanners as an additional tool for augmenting geological mapping is assessed based on 41 outcrop scans from the Gould Lake area, which is located 20 km north of Kingston, Ontario, Canada. The 3-D digital outcrop models gathered included two distinct metamorphic lithologies (marble and quartzofeldspathic gneiss) measuring up to 2.5 m high × 7 m long with an average surface area of 18 m2. This average scan size would take less than 10 min to capture, result in ~18 million individual points per scan, and provide a spatial resolution of ~1 cm for outcrop features. Throughout the course of the investigation, the main benefit of capturing multiple 3-D digital outcrop models was the ability to integrate this real-time, in situ geospatial, and geologic information across multiple visualization scales. This utility and retention of outcrop-scale geospatial information was shown to enhance the understanding of multi-scale geological relationships.
The morphological study of geological hand samples has a wide variety of applications in the geosciences, which is conventionally accomplished by measuring the distance between features of interest on the sample's surface. Close-range three-dimensional (3D) laser scanners provide an opportunity to study the form and shape of geological samples in a digital environment and have been increasingly utilized in fields such as paleontology, rock mechanics, and sedimentology, with some uptake in planetary sciences and structural geology. For paleontological studies, primary applications are in quantitative analysis of fossil morphology and integration into 3D animated models for understanding species movements. In the field of rock mechanics, typical uses of 3D digital geological hand sample models include quantifying joint roughness coefficient (JRC), determining the surface roughness of rock samples, and assessing morphological changes over time due to processes such as weathering. In the field of sedimentology, such models are incorporated to characterize the shape of sediment particles and to calculate key parameters such as bulk density. This paper aims to provide a comprehensive review of established literature that includes substantial use of digital geological hand samples acquired from 3D close-range (<1m target distance) triangulation laser scanners in an effort to identify opportunities for future progress (such as global data sharing) as well as challenges specific to the nature of geological samples (e.g., translucency) and geoscientific workflows (on and off-site).
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