Iron-gall ink has been widely used ink in the production of documents and artworks since the fifth century C.E. Terahertz imaging is used to read characters written in such ink on stacked sheets of paper. Several contrast mechanisms including maximum/minimum of the reflected terahertz signal, signature frequency, Gaussian mixture model, and short-time Fourier transform are tested to compare the image quality of the buried text. The results show that the short-time Fourier transform mechanism outperforms other contrast mechanism and has the ability to extract clear images of buried text within paper stacks.

THz time-domain spectroscopy (THz-TDS) and pulsed imaging have been demonstrated to be able to provide a non-invasive examination of cultural heritage materials. However, the spatial resolution of THz pulsed imaging is of the order of 1 mm for THz waves, a value that is often not sufficient for the examination of small details on written heritage. This paper will focus on the development of a far-field super-resolution THz imaging system based on a freestanding knife edge and a reflective confocal configuration for the THz beam line. This system has been designed for the recognition of inks, pigments, and dyes used in graphic signs and for the detection of texts buried beneath graphical layers. To optimize the set-up preliminary experiments were realized by imaging the diffraction pattern of a slit, where the freestanding knife set-up showed an improved resolution. After, a reflective set-up was realized and tested on paper samples with graphite patterns. Results demonstrated the super-resolution of THz imaging by showing written features separated by less than the wavelength used. The future direction will be the application of the set-up to real ancient documents for their diagnostics.

The possibility of integrating digital technologies facilitates the documentation and, consequently, the management of complex environments such as the Hypogean Heritage. The Grotta di San Michele Arcangelo, a natural cave located in the municipality of Olevano sul Tusciano, in the province of Salerno, is being selected as a case study to test the integration of different digital surveying technologies. Through the combined use of SLAM-based techniques, used for the acquisition of the interior space, and LiDAR-UAV techniques, for the exterior, an integrated point cloud was obtained from which accurate geometric information could be extracted, necessary for three-dimensional modeling of the analysed environment. The purpose was to provide the academic community with updated multidimensional information of the hypogean scenarios, defining good practices for their application. The database becomes an essential tool for the understanding, monitoring and management of these complex environments and also lends itself to actions of valorisation and promotion of virtual accessibility to this heritage.

The present study, through a methodology of integrated representation and survey, constitutes a contribution aimed at preserving the memory of a site of great historical, cultural and landscape value, monitoring its evolution over time. It is an integrated investigation of the original conformation of the Tiber Island in Rome, in particular of the remaining ancient portion of the so-called Stone Ship. The research aimed to compare historical iconography with two- and three-dimensional models derived from acquisitions performed with current methodologies and instruments. Through the study of the proportions of the fragments still observable in situ, it was possible to hypothesise certain architectural conformations that could evoke the primitive form. In that manner, the traces that are still evident, analysed and studied, make it possible to grasp the material and immaterial information that is useful for an overall approach to the work.

The construction of virtual and physical copies of statues is not new, but it still contains several elements to investigate. On the one hand, the pipeline for the definition of a reliable physical copy, in terms of morphometrics and material, and on the other hand, the optimization of the digital models for their virtual fruition while preserving the distinctive features. These two steps require experimentation and comparisons, allowing the processes to be validated to reach scientifically accurate results. The article, starting from the case study of the head of Sant'Elena preserved inside the Mausoleum of Sant'Elena, proposes the comparison of different processes of physical and digital 3D acquisition and reproduction of the work in order to expand its fruition both via virtual representation and for people with visual impairment.