Comparison of Window Scan and Digital Outcrop Model Approaches for Fracture Characterisation Along the Lampung–Panjang Fault Zone

Fracture characterisation is an important component of structural geological studies because fracture orientation and distribution provide insights into tectonic deformation and rock mass behaviour. However, conventional field-based fracture measurements are often constrained by limited outcrop accessibility and observation coverage. This study evaluated the applicability of Digital Outcrop Models generated from unmanned aerial vehicle photogrammetry for fracture characterisation within crystalline rocks along the Lampung–Panjang Fault zone, southern Sumatra, Indonesia. Fracture data were collected from four outcrops using both the window scan method and digital measurements derived from georeferenced three-dimensional outcrop models. The aerial imagery was processed to generate orthomosaics and digital outcrop models, from which fracture traces were identified and analyzed. A total of 124 fractures were measured using the window scan method, whereas 319 fractures were extracted from the digital outcrop models. Results showed that both approaches consistently identified dominant northwest–southeast and northeast–southwest fracture orientations across the study area. Although differences were observed in dip distributions and contour dispersion, the digital outcrop models preserved the principal fracture patterns recognized in the field while providing a larger dataset and broader spatial coverage. These findings demonstrated that digital outcrop models can reliably represent fracture geometries and serve as an effective alternative to conventional measurements, particularly in inaccessible outcrops. The study highlights the potential of drone-based photogrammetry to improve the efficiency and completeness of structural geological mapping and fracture characterisation.