Crowd-sourced SfM: Best practices for high resolution monitoring of coastal cliffs and bluffs

Digital oblique photos of an approximately 2.0 km alongshore reach of seaward-facing coastal bluff faces on the Strait of Juan de Fuca, Washington State, were collected at least quarterly between 2016 and 2022. In total over 3900 photos were collected over 38 separate surveys. The photos were collected to support digital surface reconstructions using Structure-from-Motion (SfM) photogrammetry, and specifically to assess the quality of surfaces generated with photos collected using relatively simple techniques that could be accessible to community science programs. A secondary goal was to use the photos, and the digital surfaces generated with them, to evaluate patterns and rates of erosion on the bluff face.