A low‐cost open‐source workflow to generate georeferenced 3D SfM photogrammetric models of rocky outcrops

Structure‐from‐Motion (SfM) software and unmanned aerial vehicles ( UAV s) have been increasingly adopted in the geosciences. The current mainstream generation of 3D models is still expensive as it relies on UAV s, Differential Global Navigation Satellite System ( DGNSS ) ground control points and commercial software. This paper proposes an end‐to‐end reproducible SfM workflow with minimal legal, financial or field issues. The procedure avoids both UAV s and DGNSS and relies on open‐source software. Interlocked models of a rocky shore in Normandy, France were generated at different scales and point densities, being georeferenced using free spatial data. A spherical target was used for scaling and assessing the relative accuracy, which was better than 1 cm.