A detailed method for creating digital 3D models of human crania: an example of close‑range photogrammetry based on the use of Structure‑from‑Motion (SfM) in virtual anthropology

Photogrammetry is a survey technique that allows for the building of three-dimensional (3D) models from digitized output data. In recent years, it has been confirmed as one of the best techniques to build 3D models widely used in several fields such as life and earth sciences, medicine, architecture, topography, archaeology, crime scene investigation, cinematography, and engineering. Close-range photogrammetry, in particular, has several applications in osteological studies allowing to create databases of 3D bone models available for subsequent qualitative and quantitative studies. This work provides a step-by-step guide of the photo acquisition protocol and the photogrammetric workflow for creating high-resolution 3D digital models of human crania. Our method, based on Structure-from-Motion (SfM), uses single-camera photogrammetry to capture chromatic details and reconstruct shape with a scale error of less than 1 mm. Using relatively inexpensive and easily transportable equipment and a quick and simple protocol, realistic and accurate models can be be produced with minimal effort.