Advanced Digital Imaging Center Inaugurated at the Cyprus Institute
The development of high-resolution digital visualization techniques for the documentation of ancient artifacts and works of art has been one of the major scientific achievements of the past decade. In this context, the application of Reflectance Transformation Imaging Technology (RTI) has offered great possibilities for research as well as for the documentation and preservation of cultural heritage objects.
|Within the activities of the LinkSCEEM-2 project, the Cyprus Institute has installed and is developing a tailor-made RTI imaging center, which will spearhead its contribution in the study and protection of Cultural Heritage in the Eastern Mediterranean. This imaging system is not commercially available and had to be custom built to suit the special applications in the eastern Mediterranean in general and Cyprus in particular. The whole effort is materialized in collaboration with world leading experts from the University of Southern California and the University of Illinois.||
Demonstration of the Polynomial Texture Mapping on a copy of an ancient coin from Petra, Jordan, depicting Alexander the Great or one of its successors.
The Cyprus Institute’s RTI imaging facility features two technologies:
- Polynomial Texture Mapping (PTM) is a type of RTI imaging application, which was developed by Hewlett-Packard Imaging Labs, addresses the difficulties in the photography of objects whose surfaces feature inscriptions or relief designs. They can be found on an array of archaeological objects and works of art such as inscriptions in stone or clay, plaques, coins, paintings, mosaics, relief sculpture, jewelry and other minor objects. Traditional photography of such material has serious limitations in the optimal lighting of the entire photographed object with a single light angle. Photographers are often forced either to focus on only part of the artifact or try to take additional photographs with varying light angles, a difficult and time-consuming process. The PTM system solves this problem in an extraordinary way. It consists of a dome with a hole at the apex, and thirty-six Halogen lights embedded at randomly fixed intervals around the dome. An artifact is placed at the base of the dome, while a camera is positioned looking downward focusing, through the hole at the top, on the aforementioned object. Thirty-six photographic images are taken, each with a single light shining on the artifact, thus creating thirty-images with different light angles. Then, the PTM algorithm synthesizes the data from these images to create a single image that can be displayed on a PTM viewer. The viewer allows the user to move the light angle in real time, so that the combination of light and shadow representing the relief features of the object’s surface can be freely altered. The viewer is able to study the artifact as if he/she could move a light across the object.
- Large format photography calls for a particularly high level of technical and creative skills. It requires an in-depth expert knowledge in order to exploit the possibilities to the full extent. That is the only way to produce exceptionally high detail images to match the sensor’s resolution. This is essential for pictures to be useful in subsequent analysis. Large Format Photography can be used in all types of environments for a wide range of materials. In our case, its applicability in unwrapping cylindrical surfaces from ancient cylinder seals produced enormous detail providing us with high-resolution panoramic images up to 8,000 x 65,000 pixel resolution. That is the largest digital panoramic images currently available with a wide color gamut and an outstanding dynamic range output. Our custom-built unit consists of a Sinar mechanical large format camera kit with base rails, lenses specialized in large format photography, better light digital 4”x5” scanner back that can create panoramic, rollout, QVTR images and an electrical precision motor base. The digital scanning back captures pure red, green and blue information for each pixel in resolution settings up to 8000 pixels in height. The resulting images can be well over 1 Gigabytes and provide amazing detail and tone range that could never be captured with film or Digital single-lens reflex (DSLR) cameras. The tri-linear sensor on board is not capturing an image of the subject in front of the camera all at once as any normal camera does, but rather by physically moving a unique, highly-optimized tri-linear color image sensor smoothly across the image plane, building up the image one line per color at a time. The sensor is a patent of Eastman KODAK the world leaders in photographic mediums and equipment.
This Large Format unit at the Cyprus Institute is being customized for the needs of cultural heritage researchers and managers in collaboration with the University of Southern California. It is fully flexible for add-ons so to fit the criteria of any case study (e.g art reproduction, conservation/restoration, spectral imaging and archiving).
Following installation, a two-day introductory seminar session was held at the Cyprus Institute Athallasa Campus for staff and invited members from the Department of Antiquities and other institutions such as the Bank of Cyprus Cultural Foundation and the Leventis Municipal Museum of Nicosia. Local experts were trained on the new sophisticated imaging equipment.
|A pilot study at the Bank of Cyprus Cultural Foundation and a second at the collections of the Leventis Museum have been completed highlighting the benefits this new tool in digital imaging will bring to the conservation and further study of the rich and diverse history of Cyprus. Collaborative thematic research projects are already planned focusing on shedding new light on the study of archaeological material and works of art.||
Participants during the training workshop and live demonstration with hands-on-training on the technologies installed at CyI and introduced by the University of Southern California and the University of Illinois.
The development of this RTI Imaging facility that underlines the great benefits of bringing together forefront digital technologies with archaeology and cultural heritage was made possible under the umbrella of EU funded project LinkSCEEM-2 coordinated by Prof. Alexandrou at the Cyprus Institute and the assistant of many Cyprus Institute staff. The early success and promising potential of the specific imaging application and research demonstrates the effective strategies pursued actively by the Institute’s Computation-based Science and Technology Research Center (CaSToRC) and the Science and Technology in Archaeology Research Center (STARC).
Actively involved in this early stage of the RTI Imaging facility’s development were:
- Ropertos Georgiou (Cyprus Institute, STARC), Nikolas Bakirtzis (Cyprus Institute, STARC)
- Marilyn Lundberg (University of Southern California), Ken Zuckerman (University of Southern California)
- Wayne Pittard (University of Illinois at Urbana-Champaign)