Photogrammetric survey with fisheye lens for the characterization of the La Sassa cave
The survey of ancient cave can generally be performed by traditional topographic methods that allow also its georeferencing in a global
reference frame; some difficulties may arise when there are narrow tunnels that do not consent the use of a total station or a terrestrial
laser scanner. In such cases a visual-based approach can be used to produce, both the followed path and the 3D model of the hypogeal
environment. A prompt photogrammetric survey has been used to reconstruct the morphology of the La Sassa Cave, situated in the
municipality of Sonnino (Latina), in the lower Lazio region. In this cave, a very large quantity of Pleistocene animal bones was found,
together with several fragments of Copper Age human bones and Bronze Age impasto potsherds.
The survey was carried out using a DSLR full frame camera Nikon D800E with a Nikkor 16 mm fisheye lens pre-calibrated. During
the acquisition, several targets were measured in order to contain the deformations model. The photogrammetric model has been
georeferenced using 3 GCPs positioned outside the cave entrance where a double frequency GNSS receiver has acquired data in static
session mode.