Digital Caligula

Modern 3D Technology Virtually Restores an Ancient Roman Sculpture

Projects - UVA Caligula Sculpture

The city of Rome is one of the most popular destinations in the world owing to the culture, the architecture, and especially the art that remains from its ancient citizens. Every year millions of visitors visit the travertine stone remains of the Coliseum, the Roman Forum and other amazing sites wondering what life must have been like at the height of the Empire.

Dr. Bernard Frischer of the University of Virginia and the Virtual World Heritage Laboratory employs modern 3D technologies to answer that question. In 2007 he initiated the “Rome Reborn” project to build a 3D digital version of the original Rome in circa 320 A.D. Today he is directing the Digital Sculpture Project to exploit 3D scanning and modeling technologies for the “capture, representation and interpretation” of ancient sculpture.

Over the past year, Direct Dimensions worked with Dr. Frischer’s team to digitally recreate a famous life size marble sculpture of the Emperor Caligula from 1st century Rome. This project resulted in a unique combination of world class 3D technologies with internationally acclaimed academic research.

The Caligula sculpture is owned by the Virginia Museum of Fine Arts (VMFA) and, as one of only two complete existing sculptures of the Emperor, is also considered one of the most important Roman “portraits” in the United States. While the sculpture is in generally good condition, it suffered damage through the years such as losing its nose and hands, missing chucks of the toga, and a poor repair job some years ago that mis-located his head.

A team of experts from around the world was assembled to research how the Caligula sculpture might have looked when it was first created. But how would the team collaborate with scientific accuracy on such a large complex sculpture located in Virginia?

The answer: utilizing advanced laser scanning technology to accurately digitize the physical sculpture, thus allowing the team to collaborate virtually in 3D.

In September 2010, our engineers travelled to the Virginia Museum of Fine Arts where they spent a full day capturing the Caligula sculpture with a laser line scanner mounted on a Faro Arm portable articulating digitizer. They scanned the entire complex piece with an accuracy of about one-tenth of a millimeter and resolution of nearly a quarter millimeter. The resulting 3D point cloud file was over 1.5 GB and contained nearly 137 million points.

Back at the DDI facility in Baltimore, the raw laser data was processed into a super high resolution polygonal model using Innovmetric’s PolyWorks Modeler software. For technical reference, the final model was nearly 400MB in size and contained over 9 million polygons. Since this model was watertight, we also calculated the exact surface area of marble, just under 5 million square millimeters.

However, this “exact” digital replica model of the existing condition piece was only the first step in our work. The goal for the project was not simply to recreate the Caligula sculpture as it looks today but how it might have looked when it was originally created almost 2,000 years ago. Given its current condition, this meant digitally restoring the missing hands and nose, replacing the missing pieces of the toga, and even “repainting” the sculpture. (Note: while all that we see today is the marble, the ancient Romans actually painted their sculptures in brilliant colors which have worn off over the passing years.)

To perform these tasks, the Direct Dimensions’ digital modelers worked in close collaboration with the international academic research team to digitally resculpt and repaint the missing elements of the sculpture. Using ZBrush software, for example, our modelers created the shapes for the missing parts such as the hands. The academic experts then indicated how we needed to adjust these hand positions to be representative of the time period. Using those examples, exchanged digitally across the internet, the DDI modelers were able to iteratively sculpt multiple new versions of the missing components. The research team was then able to suggest edits based on their hypotheses, leading to the creation of multiple digital models. This process was repeated for many of the missing elements and also to help with the positioning of the separated head. After exchanging and studying many iterations, the researchers ultimately selected the final configurations and the project continued to colorization.

When it came time to repaint the digital model, it turned out that very faint traces of the original polychromy (color) still existed allowing the research team to provide a likely color scheme to Direct Dimensions. Again using ZBrush, the DDI modelers created a layering of colors on the digital model which they could turn on or off to display likely depth of color to the academic researchers. For instance, trace findings indicated that part or all of the toga was once painted purple and the model was able to display slightly different purple colors as well as options for an entirely purple toga and also a simple purple sash.

The final digital model was unveiled to the VMFA on December 4th, 2011, during a special symposium entitled “Caligula 3D: Man, Myth, Emperor”.

Direct Dimensions is very proud to have contributed its technical capabilities to such an important project. Hopefully more museums and research groups will adopt these 3D technologies for similarly important projects.