Abstract
Maritime Theatre is one of the most iconic buildings of Hadrian's Villa (UNESCO site since 1999). This circular-shaped “domus” is characterized by one of the most obvious aspects of Hadrianic architectural production, namely the alternation of curved and straight lines applied to designing both plans and elevations. Mixtilinear features caught the interest of architects from the Renaissance to present day, becoming inspiration as well as a sort of “quarry” for noble families and antiquarians. Complex entablatures designed by Hadrian's architects have been systematically removed and reused starting from Middle Ages with the consequence of having several fragments scattered in private and public collections all over Europe. Through a systematic digital survey of remaining structures as well as of removed elements, a 3D analytical model was exploited in order to include all the “digitally gathered” elements and for deepening the knowledge of this emblematic mixtilinear architecture.
TopIntroduction
Architects have always shown a keen interest in the buildings of Hadrian’s villa. Ever since the Renaissance, when this site regained its identity as the astonishing mansion of the Emperor, architects have been visiting the ruins to study the often extremely bold architectural orders and features and draw inspiration for their own works. The villa is considered a place that “combines the best elements of the architectural heritage of Egypt, Greece and Rome”, as reported in the reasons for the site’s inclusion in UNESCO’s World Heritage List (1999), especially for its classical architecture, interpreted - in the light of Hadrian’s vision - in an eclectic sense. The emperor’s residence at Tivoli is seen as a masterful accomplishment that brings together elements drawn from Greek architecture (in all its forms from the archaic to the Hellenistic periods) and the knowledge and experience of Roman culture, above all building techniques.
Opus caementicium (Roman concrete), for instance, was a fundamental conquest in terms of constructing slim coverings and roofing even over very large areas, as we can find in Hadrian’s architecture.
The present chapter is focused on one of the most iconic buildings of this site, the Maritime Theatre that in some way encompasses the main features of Hadrianic architecture: among them is the well-known preference of the Emperor towards the alternation of curved and straight architectural elements - the mixtilinear style - which characterizes the ichnography of most luxurious villa’s buildings. Those pavilions caught the interest of architects from the Renaissance to our days, from Pirro Ligorio to Borromini, from the pensionnaires de l’Academie de France to John Soane, Le Corbusier, and architects of the last century1.
For several years, the institution in charge of the site safeguard and promotion (Istituto autonomo “Villa Adriana e Villa d’Este”) has been working together with the Dipartimento di Architettura (DA) of Alma Mater Studiorum - Università di Bologna in a multi-disciplinary group of archaeologists, architects and engineers. The research, not yet concluded, evolved along several directions. The branch on which we are dealing with in this essay is a specific application of ranging devices and digital modelling tools to study and verify the architectural solutions adopted in this mixtilinear play between curved and linear elements2. The aim is a better understanding of architectural decorations in order to “virtually” reassemble all figured elements that have been removed during the centuries and re-used in different contexts3.
At Hadrian’s Villa, the entablatures in Luna marble, alternated with noble Greek, African and Eastern marbles, worked in synergy with the masonry made by different materials and techniques: brick-walls in opus mixtum and opus latericium or tufa-walls, while local travertine (lapis tiburtinus) was used as structural support to reinforce foundations and housings for architectural elements.
Interest in these elegant examples of architectural trabeations with ornamental and figurative designs started far back, following the discoveries of the first excavations undertaken by the Renaissance and documented by artists and architects, as the Neapolitan Pirro Ligorio, who was one of the first who studied the complex of the villa, and described its imposing ruins, leaving us also some designs and sketches. Impressed by its refined decorations, Pirro extracted several ornamental and architectural elements and sculptures to adorn the mansions of Cardinal Ippolito II of Este4, in Rome (Quirinale Villa) and Tivoli (Villa d’Este).
The sculptured decorations on the entablatures of the Golden Court (Piazza d’Oro) and the Maritime Theatre (Teatro Marittimo) are linked by three subjects of the same theme, the erotes, taking part in marine processions with other mythological partners or racing on chariots or busy in hunting. These reliefs, displaying the child winged gods, show an exquisite quality and style, which justify their presence only in the most elegant buildings of Hadrian’s villa.
Key Terms in this Chapter
Subsurface Scattering (SSS): Also known as subsurface light transport (SSLT) is a phenomenon concerning light transportation beneath the surface of a translucent object (marble, leaves, wax): the light is in part reflected and in some measure penetrates the surface and then it passes back out of the material at an angle other than the angle it would have if it had been reflected directly off the surface. When translucent surfaces are scanned, this physical effect affects the result of the measurement producing unwanted results.
Hadrian’s Villa: Hadrian’s Villa (Villa Adriana) is an archaeological complex built during the 2nd century AD near Tivoli (Italy) by the Roman Emperor Hadrian. The complex contains over 30 important buildings, covering a large area (over than 100 ha), and is still partially unexcavated. Since 1999, the complex has been part of the UNESCO World Heritage Sites (UNESCO WHL) because of its uniqueness representing the ancient Mediterranean culture.
Reverse Modelling: The term describes a set of procedures aimed at converting a mesh model from active or passive sensors into a NURBS made of a continuous series of patches or a solid model. The process starts with a segmentation phase, namely the detection of primary and secondary surfaces, then followed by the detection of geometric features (curves) and relevant sections of the model. Curves are used for the construction of a CAD model that will be compared with the scanned data.
Displaced Subdivision Surface (DSS): It represents a detailed surface as the output of a subdivision surface in combination with a scalar field (a displacement map) applied to a parametrization of the model. The DSS is then a variable level of detail surface, or smooth domain surface, with a height field applied. By means of a render-to-texture process, or “baking” it is possible to convert a detailed geometric model (from photogrammetry or laser scanner) into such a representation. DSS is than a faithful expression of a detailed model and it offers several benefits, including geometry compression, editing, animation, scalability, and adaptive rendering. The encoding of fine detail by means of a scalar function makes the representation extremely compact. OpenExr file format allows the possibility to store inside a HDR image high frequency details that a common greyscale bitmap could not achieve.
Opus Mixtum: It literally means “mixed work” and it is an ancient building technique used by Romans especially since the age of Emperor Hadrian (2nd century AD). It consists of different opera mixed in the same wall: most of the elevation is made in opus reticulatum (in this case with tufa elements) horizontally separated by brick-patterns, while the corners and also the door and window jambs are made in opus latericium (bricks).
Quad Mesh: Are structured grids of polygons, with regular connectivity and in general characterized by valence equal to four, namely in each vertex meet four edges. This model is highly space efficient for two reasons: the first is the easy selection of loops of polygons and edges the second is that edge loops of are generally built (by a user) or calculated (thanks to quad-remeshing algorithms) to follow curvature flow and formal feature.
Opus Caementicium: Also called Roman concrete, it is a building technique used by Romans for constructions starting from 2nd century BC. It consists of an aggregate of mortar and stones and even pozzolana for hydraulic purposes and thanks to its characteristics ensured the durability over time of still existing Roman monuments.
Subdivision Surfaces: Subdivision surfaces are a representation technique that includes a series of methods aimed at converting a coarse mesh model into a smooth piecewise surface. The smooth surface is the product of the conversion of a mesh called control cage into a theoretical limit surface obtained through of a recursive algorithm of subdividing (Catmull-Clark, Doo-Sabin, etc.).