Bringing the Domitilla Catacomb out of the Dark: Photogrammetry in Action

The first presentation at the EAGLE Conference was by Antonio Enrico Felle and Norbert Zimmermann who work on the Domitilla Project in Rome, and it was arguably one of the most impressive projects I’ve ever seen at a conference. The project has been working since 2006 to create a full 3D model of the Domitilla catacomb, 12km of subterranean burials from the 2nd to 5th centuries CE, which showcases one of the largest inventories of catacomb painting from early Christianity in Rome.

The catacomb was founded by Flavia Domitilla, niece of the emperor Domitian in the 2nd c CE. Christian burials were forbidden within the walls of Rome, so these subterranean burials had to be outside the city limits and there are at least 40 outside of Rome that have been discovered to date. Today catacombs provide the best examples of early Christian art; the Domitilla catacomb itself has over 80 painted tombs, and in the 5th century CE an underground basilica was added and became a pilgrimage sanctuary for the graves of martyrs Nereus and Achilleus.

Flavia Domitilla van Terracina, Nereus en Achilleus, Peter Paul Ruebens 1608

Flavia Domitilla van Terracina, Nereus en Achilleus, Peter Paul Ruebens 1608

The project’s goal was to create a 3D scan of the catacomb in order to facilitate research of the paintings and inscriptions found within, but also so that each feature of the site – chamber, painting or inscription – could be properly geotagged with their exact location. This would allow archaeologists to date the chronological development of the catacomb based on the dates of the tombs, paintings and inscriptions with more precision than had previously been possible.

Domitilla Project

Domitilla Project

Beginning in 2006 with three scanning campaigns, the team set out to determine the viability of using 3D laserscanners to create a digital copy of the catacomb.

The scanner orientates itself on temporarily applied reflector points (Fig.1). In 360-degree panorama-scans it generates so-called point clouds, which reproduce the surrounding area of about 1 m distance as a 3D-structure. In order to connect several scans with each other, further scan positions with at least five already known reflector points are selected. At the same time as the scan, a digital camera mounted on the scanner produces photo data that can directly be applied onto the point cloud. The advantage of this method lies in the mobility of these point clouds, which can be viewed from the outside as well as the inside and which can be virtually entered. Depending on the projection and position, a ground plan, cross- and longitudinal sections and 3D views are retrievable.

Once successful tests had been completed, the team moved forward with the scanning – moving the laserscanner eight meters for each set of shots, the scanner would record 2,000 points at each set up. They estimate they did two months of post-processing for every two weeks of fieldwork, and scanning continued through the beginning of their 2009 season when they registered the 1,800 single scans into a comprehensive point cloud. The final point cloud for the entire catacomb model contains 2 billion points, each with digital coordinates. This means anyone searching the model can pinpoint exactly where each feature of interest is located, and brings the epigraphy, topography, archaeology and art history of the catacomb together in a single application. Now that the digital scanning is complete, they are working on bibliographic information on the paintings and the saints buried in the catacomb.

To create photorealistic 3D models of the fresco paintings, meshed models are calculated from the point clouds and high resolution digital photos are applied to the model:

Domitilla fresco of  the so-called Chamber of King David

Domitilla fresco of the so-called Chamber of King David

The future of the project is a joint venture working with Terapoints on creating high quality visualizations of large data sets, such as the Domitilla Catacomb, as well as integrating the 3D photos of frescoes into the model.

In order to use the precise scan data as directly and unaltered as possible, the Domitilla-team was enhanced by new collaboration partners: the Institute of Computer Graphics and Algorithms of the Technical University of Vienna and the company Imagination, which are jointly developing the point-cloud viewer Scanopy. With its help extremely large point-clouds can be viewed in real time; the goal is to further develop this program according to the needs of archaeologists and building researchers.

There are some incredibly exciting developments in archaeological reconstructions happening these days. We’ve come such a long way from Sir Arthur Evan’s controversial reconstructions at Knossos. Digital models can be reconstructed, reinterpreted and manipulated a thousand different ways without ever degrading or damaging the fragile archaeological remains, which affords researchers more opportunity to explore theoretical reconstructions than ever before. And once the initial scans are done, digital sites are accessible to anyone with an internet connection, meaning it would be entirely possible to do a tour of the Domitilla Catacomb in any classroom in the world. There is no replacement for seeing sites like this in person, but for so many of us, travel and access to sites like this are simply out of reach; he Lascaux Caves, for example, have been closed to public viewing since 2008 because of fungus that threatens the paintings and requires careful monitoring so the images are not lost forever. Digital modelling offers a simple solution to problems of accessibility and responsible cultural heritage management.

For those in the Vancouver area with an interest in photogrammetry, the Vancouver AIA and From Stone to Screen are hosting a free workshop this Saturday, October 18th from 1-4 where participants will learn to create their own 3D models – email photogrammetry@gmail.com to reserve your spot! No prior knowledge required, just a camera and laptop.

 

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Filed under Archaeology, Digital Classics, Digital Cultural Heritage, Photogrammetry

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