VIRTUAL RTI APPLICATION ON 3D MODEL FOR DOCUMENTATION OF ANCIENT GRAFFITI: PROPOSAL OF A METHODOLOGY FOR COMPLEX ARCHAEOLOGICAL SITES

In the field of Cultural Heritage, the technological advances of recent years have enriched and optimised the possibility of documenting and studying ancient graffiti with a wide range of low-cost and non-invasive methodologies. The most popular are digital photogrammetry SfM (Structure from Motion) and RTI (Reflectance Transformation Imaging) methodologies. The RTI is a powerful tool that, through the use of open source software, enables the documentation of data that are difficult to visualise, facilitating the recognition of traces and marks on the surface of objects. On the other hand, the SfM 3D models are increasingly replacing documentation with traditional photographs. This ‘almost excessive’ production of three-dimensional models is not often accompanied by an adequate exploitation of all their potential uses. This research aims to investigate the possibility of using a high-resolution 3D model for the implementation of virtual RTI processing, a hybrid method that combines 3D, virtual manipulation and 2D technologies in a fast and intuitive workflow suitable for the documentation of a wide range of archaeological monuments. The process sees the 3D model from the SfM survey being illuminated and photographed in a virtual dome in the open source Blender environment; therefore, the images generated are processed with RTI Builder software.