Grotta Romanelli portable art: GRM1023 photogrammetric model

On the occasion of the review of the portable art of Grotta Romanelli, a decorated stone with a feline figure, GRM1023, was object of an interdisciplinary study. The object was threedimensionally recorded using both optical scanning and photogrammetry. For the photogrammetric model, an automated setup to acquire a total of 207 pictures/photos was used. For this shooting, an automatic turntable (Miops Capsule Pan) was programmed to handle both the rotation of the object and the triggering of the camera. During the scanning, the camera was fixed and the subject was manually repositioned after each orbit of the turntable, for a total of 5 different positions. The process was later repeated by placing the camera at a different height. The pictures were obtained by using a Nikon D800, a 36 MP full frame sensor digital camera, with a macro lens (Nikkor AF-S 60mm Micro f/2.8 G) and a circular polarizer filter (Hoya Pro1 Digital Filter). A ring flash (Quantuum Quadralite RX400) was used for lighting, paired with a linear polarizer to make best use of cross polariSation and avoid unwanted glares and/or reflections that could have undermined the quality of the reconstruction. The pictures were then processed by using Agisoft Metashape 1.8.5 that generated the sparse cloud, the final mesh directly from the depth maps, and the texture. The final 3D model has 1,759,728 faces and 879,876 vertices (Lai et al., 2023).