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Reassembling the Thera Frescoes:
Automated Digitization and Matching of Fragments
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Summary
The archaeological site of Akrotiri on the island of Thera (modern-day
Santorini) has proven a treasure trove of information about Aegean
civilization and culture. Among its most valued artifacts are wall
paintings (frescoes), which have been preserved in the volcanic ash
since the seventeenth century BCE. The frescoes, however, are typically
recovered in fragments of a few centimeters to a few tens of centimeters
in length, and reconstructing complete wall sections occupies a major
portion of the effort at Akrotiri.
We are engaged in a project to assist archaeologists and conservators by
digitizing excavated fragments and using computer algorithms to
automatically propose matches on the basis of 3D edge profile, color,
and other cues. An intuitive user interface will allow conservators to
see and evaluate matches on the basis of any or all of the above
criteria. We hope to greatly reduce the time that is currently spent
manually testing large numbers of fragments against each other in the
search for matches.
Our project has three major components:
- Acquisition.
Beginning with commercially-available color and 3D scanners, we are
building a hardware configuration for capturing the color texture of
each fragment, together with its thickness and 3D shapes of the edges.
We are writing custom software to control the scanners, ensuring that
capture is easy (may be performed by non-computer-experts) and fast (no
more than a few minutes per fragment). All captured data is stored
together with semantic information about the fragment, as well as any
annotations provided by archaeologists and conservators.
- Matching algorithms.
Building on recent research results, we are investigating a system for
computing candidate matches between fragments, and proposing them to the
user for verification. We will explore different cues for performing
this matching, including the 3D shape of edges, fragment thickness,
color and edges on the surface, any user-supplied annotations, and
arbitrary combinations of different cues.
- User interface.
We are developing a computer program that allows users to move fragments
or groups of fragments on the screen, easily evaluating the proposed
matches. The software keeps track of information associated with each
fragment, including excavation data, annotations, and the color and 3D
scans. In addition, there is data associated with each match, including
the quality of the match and any conservators' annotations. The
software will also include features such as revision control and support
for concurrency, allowing multiple users to work either simultaneously
or serially.
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