Review of close-range three-dimensional laser scanning of geological hand samples

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 (< 1 m 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).