How 3D models (photogrammetry) of rock art can improve recording veracity: a case study from Kakadu National Park, Australia

Creating an inventory of a rock art site in the field can be time-consuming and expensive, but Structure-from-Motion (SfM) photogrammetry has the potential to alleviate these issues. Using SfM, rock art sites can be recorded rapidly, with a 3D model created to allow a digital inventory to be compiled. However, the veracity of a digital inventory can be questioned. At the Blue Paintings site in Kakadu National Park, Australia, we tested two field inventories against a digitally-derived inventory and ground-truthed the results. The results demonstrated that the digitally-derived inventory was slightly less comprehensive than the field recordings, but only unidentified lines and blotches were lacking; this would not necessarily adversely influence interpretation. Furthermore, the field inventories conducted by different people also had variations, demonstrating that whether the inventory is done on a 3D model or in the field, an inventory is still a human interpretation.