3D-Acquisition and Multi-Spectral Readings for Documentation of Polychrome Ceramics in the Antiquities Collection of the Kunsthistorisches Museum Vien 
Paul Kammerer, Vienna University of Technology, Austria
Hubert Mara, PIN - Univ. of Florence, Italy
Elisabeth Trinkl, Austrian Academy of Sciences, Austria
Ernestine Zolda, Vienna University of Technology, Austria
Motivated by archaeological requirements we are developing an automated system using 3D-acquisition based on structured light for documentation of ancient ceramics. Furthermore we are developing a system for art-historic analysis of medieval paintings using multi-spectral readings of color pigments. In the past both systems have been developed and tested independently at various archaeological excavation sites in Austria, Turkey Israel and Peru for ceramics and on paintings from the Belvedere collection in Austria (Project Cassandra).
Having polychrome ceramics (Lekythoi) from the Attic period of the partially unpublished collection of antiquities of the Kunsthistorisches Museum in Vienna, we combined these two systems for their documentation. Therefore 20 Lekythoi and further 107 ceramics have been acquired with a 3D-scanner using structured light and a digital camera resulting in a high-resolution 3D-model (<0.1mm) containing the texture map (color information of the surface). As the texture map does only describe the colors seen by the human eye, we choose to add multi-spectral readings to determine the reflection properties in the full spectrum of light (Infrared to Ultraviolet), which leads to classification of the ingredients used for the paint. This classification can be used for two different tasks: 1. Virtual restoration of faded colors. 2. Determination of the origin of the color and the coloring technique. Especially the second task is a new tool for museums to confirm the unconfident origin and to detect faked ceramics in case they were added to the collection in past centuries. Finally the setup for the multi-spectral readings was acquired with the 3D-scanner and registered to the 3D-model of the ceramics. This allows a precise (<0.1 mm) location of readings of points of interest (e.g. red paint for coats and hair) for proper documentation and compensation of deviations introduced by the curvature of the surface.
The presented work was conducted within a project for a new volume of the Corpus Vasorum Antiquorum (CVA). Therefore we show results for the traditional publication based on 3D-models by automatically estimated drawings, which is generally a horizontal cross-section (profile-line) and arbitrary cross-sections e.g. for handles. Additionally we show the unwrapped paintings and views rendered for printed documentation with the registered multi-spectral readings. This enables experts to study visible and invisible aspects of the colored surfaces and can be used for the public in a virtual show-case for ceramics not shown in the exhibition due to limited space for displays. Furthermore we show that the proposed - combined - system is conservative, because it is contact-free, radiation-free and can be applied in an efficient way by acquisition of up to ten ceramics a day within the museums storage. All work has been done with respect to the London-Charter to ensure the intellectual integrity, reliability, transparency, documentation, standards, sustainability and accessibility of the information gathered by 3D-acquisition.
Demonstration: Demonstrations [Close-Up]
Keywords: 3D-acquisition, mult-spectral readings, ceramics, documentation, digital preservation, museum application
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