In this paper, we discuss the requirements and technical challenges within the EHEM project, Enhancement of Heritage Experiences: The Middle Ages, an ongoing research program for the acquisition, analysis, documentation, interpretation, digital restoration, and communication of medieval artistic heritage. The project involves multidisciplinary teams comprising art historians and visual computing experts. Despite the vast literature on digital 3D models in support of Cultural Heritage, the field is so rich and diverse that specific projects often imply distinct, unique requirements which often challenge the computational technologies and suggest new research opportunities. As good representatives of such diversity, we describe the three monuments that serve as test cases for the project, all of them with a rich history of architecture and paintings. We discuss the art historians’ view of how digital models can support their research, the expertise and technological solutions adopted so far, as well as the technical challenges in multiple areas spanning geometry and appearance acquisition, color analysis and digital restitution, as well as the representation of the profound transformations due to the alterations suffered over the centuries.

This paper summarizes the main results of the study, diagnostics, and restorations conducted and applied to a 16th century wall painting (a portion of the frieze and the Riario coat of arm) in Palazzo Gallo (Bagnaia, Viterbo district—central Italy) recently concluded, which was also the subject of a master’s degree thesis in Conservation and Restoration of Cultural Heritage at the University of Tuscia, Viterbo. Innovative imaging techniques were used for the first time on a wall painting on-site: hypercolorimetric multispectral imaging (HMI) and pulse-compression thermography (PuCT), combined with more traditional analysis such as X-ray fluorescence spectroscopy, Fourier transform infrared spectroscopy, and cross-section investigation. HMI allowed for mapping the conservation status before and after the removal of the scialbo layer that covered the original paintings. It also allowed different areas of the painting to be compared and for verifying the effectiveness of the cleaning. PuCT enabled the detection of cracks and discontinuities in the ground layers and to evaluate the depth of such anomalies, giving valuable support in the consolidation step. Moreover, passive thermography was used to monitor the penetration level of a hydraulic mortar in real time, a technique that was greatly helpful for verifying the successful fill and consolidation of voids beneath the pictorial layer. Overall, the multi-technique approach reported here was of considerable assistance for restoration of the mentioned artwork, the result of which has also been documented.

(1) Background: This paper illustrates an innovative methodological approach chosen to study and map the colors of the medieval wall painting of Santa Maria Antiqua in the Roman Forum, one of the pilot sites of the EHEM project (Enhancement of Heritage Experiences: The Middle Ages). Digital Layered Models of Architecture and Mural Paintings over Time). (2) Methods: Two methods were employed to gather information about colors and mapping. Specifically, colorimetry was utilized for spot measurements, and hypercolorimetric multispectral imaging (HMI) was employed to map the same colors sampled through colorimetry. (3) Results: Chromatic data for all colors in the wall paintings were obtained in the CIELAB color space. Additionally, chromatic similarity maps were generated using the innovative HMI system, a multispectral imaging technique capable of obtaining color data information through advanced calibration software named SpectraPick^® (Version 1.1). This comprehensive approach facilitates a thorough understanding of color characteristics and distribution. (4) Conclusions: The color measurements and mapping represent significant advancements in the interpretation of medieval wall paintings, which are often fragmentary and stratigraphically complex. This research sheds new light on the colors used and enhances our understanding of the original appearance of the iconographic patterns. Furthermore, it enables the reconstruction of colors that closely resemble the originals.

This article concerns the diagnostic campaign aimed at analyzing the mural painting representing the iconographic theme of the Deesis of the Church of St. Maria Annunziata, Motta San Giovanni, in the province of Reggio Calabria. In 1951, a flood caused the collapse of the building and the consequent breaking of the apse into two parts. The present study focused on the left side of the apse, hosting the figures of Christ and Mary, in order to plan the best conservation intervention strategy. For this purpose, non-invasive investigations and laboratory analytical methods were conducted in order to characterize the constituent materials and to identify the forms of alteration and degradation present on the surface of the painting. In particular, Raman spectroscopy, optical microscopy, scanning electron microscopy coupled to the chemical analysis by an EDS probe, Fourier-transform infrared spectroscopy and ion chromatography were employed. The results highlighted the presence of a single layer of plaster made with a lime-based binder. The chromatic palette of the painting is characterized by ochres and carbon black mixed with lime to obtain the different shades. Finally, the definition of the nature of the deposits and of the overlaid materials was fundamental in order to identify the best products and methods to restore the readability of the work.

(1) Background: This paper illustrates an innovative methodological approach chosen to study and map the colors of the Medieval wall painting of Santa Maria Antiqua in the Roman forum, one of the pilot sites of the EHEM project (Enhancement of Heritage Experiences: The Middle Ages. Digital Layered Models of Architecture and Mural Paintings over Time); (2) Methods: We chose to use two methods for gathering information about colors and mapping, specifically colorimetry by spot measurements and hypercolorimetric multispectral imaging (HMI) to map those same colors sampled through colorimetry; (3) Results: Chromatic data of all colors in the wall paintings were obtained in the CIELAB color space. In those same points, chromatic similarity maps were performed by the innovative HMI system, a multispectral imaging technique able to obtain also color data information by means of the advanced calibration software named SpectraPick®: this allowed to have a complete knowledge of the color characteristics and distribution; (4) Conclusion: The color measurements and mapping was an important result to improve the reading of Medieval wall paintings, fragmentary and stratigraphically complex, giving a new light in the knowledge of the colors and allowing to better understand the original appearance of the iconographic patterns, reconstructed with colors as faithfully as possible similar to the originals.

Ultraviolet-induced fluorescence (UVF) imaging represents a simple but powerful technique in cultural heritage studies. It is a nondestructive and non-invasive imaging technique which can supply useful and relevant information to define the state of conservation of an artifact. UVF imaging also helps to establish the value of an artwork by indicating inpainting, repaired areas, grouting, etc. In general, ultraviolet fluorescence imaging output takes the form of 2D photographs in the case of both paintings and sculptures. For this reason, a few years ago the idea of applying the photogrammetric method to create 3D digital twins under ultraviolet fluorescence was developed to address the requirements of restorers who need daily documentation tools for their work that are simple to use and can display the entire 3D object in a single file. This review explores recent applications of this innovative method of ultraviolet fluorescence imaging with reference to the wider literature on the UVF technique to make evident the practical importance of its application in cultural heritage.