A System for High-Volume Acquisition and Matching of Fresco Fragments: Reassembling Theran Wall Paintings

Abstract

Special seminar at the Center For Engineering Outreach.

The archaeological site of Akrotiri on the volcanic island of Thera (modern-day Santorini, Greece) has yielded an unparalleled trove of artifacts and information from the prehistoric Aegean. The ancient civilization was destroyed by a volcanic eruption, which buried the remains of a flourishing Late Bronze Age (c. 1630 B.C.) settlement in ash. Among the most significant finds are numerous wall paintings, ranging from naturalistic and narrative scenes to abstract motifs. However, these paintings are recovered as thousands of plaster fragments, and reassembling them consumes a substantial portion of the effort expended at Akrotiri.

I will describe a system that uses 3-D and 2-D digitization hardware, together with computer-based matching techniques, to assist archaeologists and conservators in documenting and reassembling the wall paintings. Although mature technologies exist for acquiring images, geometry, and surface normals of small objects, they remain cumbersome and time-consuming for non-experts to employ on a large scale. Our system addresses the scalability, usability, and quality challenges of large-scale 3-D and 2-D digitization, by incorporating new algorithms to automatically align 3-D scans, register 2-D scans to 3-D geometry, and compute surface normals from 2-D scans. A novel 3-D matching algorithm efficiently searches for matching fragments using the scanned geometric models.