Ricerc@Sapienza

This paper presents some of the results obtained from the integrated use of 3D surveying techniques and illustrates some types of analysis and graphic representations that can be conducted and reproduced. The case study concerns the church of San Nicola in Montedoro that is one of the oldest in the city of Martina Franca in the province of Taranto (Italy) and presumably dates back to the fourteenth century.

Sometimes, the georeferencing of a cave in the global reference system can be challenging. Some difficulties may arise when narrow passages do not allow the use of classical topographic equipment or a terrestrial laser scanner. In these specific cases, the surveyor can employ a visual-based approach to produce both the followed path and the 3D model of the hypogeum. The report we are presenting is the result of a survey in the Guattari cave carried out using images taken by a Huawei P9 mobile phone and a Nikon D800E camera with a 16mm fisheye lens.

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

Caves have been used by humans and animals for several thousand years until present but, at these time scales, their structures can rapidly change due to erosion and concretion processes. For this reason, the availability of precise 3D models improves the data quality and quantity allowing the reconstruction of their ancient appearance, structure and origin. However, caves are usually characterised by lack of light, high percentage of relative humidity, narrow spaces and complex morphology. Thus, quite often the traditional topographic instruments cannot be employed.

In the geomatics field, modelling and georeferencing complex speleological structures are some of the most challenging issues. The use of conventional survey methods (for example, those employing total stations or terrestrial laser scanner) becomes more difficult, especially because of the space constraints and the often critical light conditions. In this work, a flexible and swift methodology to survey an in-progress excavation is presented, through image-based modelling techniques.