Switzerland 2005: Expedition to the Alps
A Journey of Discovery
This project was completed in 2005. The following article is by Claudia Willen.
Cultural Heritage Imaging (CHI) co-founders Mark Mudge and Carla Schroer, and CHI's imaging director Marlin Lum, adapted Reflectance Transformation Imaging (RTI) technology to document artifacts spanning millennia of human history from three awesome archaeological collections in Switzerland.
|Relevant Fields||Archaeology, anthropology, art history, museum studies and management, preservation projects, private and civic collections, libraries, galleries, and archives.|
|Research Issue||Creating 3-dimensional (3D), archival quality images for diverse artifact collections. The objects occur in a variety of shapes and sizes. The artifacts have many different surface qualities, ranging from highly reflective metal coins to items with worn or partially obscured inscriptions. Many of the items are extremely valuable, light-sensitive or fragile and cannot be handled very often. The Swiss archivists who manage the collections have very precise documentation requirements. Imaging data must be reliable, consistent, reproducible, and based on exacting standards.|
|Solution||New imaging technologies for capturing, processing, archiving, and presenting 3D images of artifacts. Cultural Heritage Imaging (CHI) and Hewlett-Packard Laboratories (HP Labs) developed these techniques.|
|Results||114 objects from 3 collections photographed and documented in 14 days. Data captured for 186 luminous 3D RTI files and 7 object movies. More than 40 gigabytes (GB) of raw data archived for further processing and analysis.|
|Benefits||The high-resolution 3D image files are versatile enough to be used for many purposes, such as documentation, archiving, presentation on the Web, in print, in museum or gallery displays, kiosks, and interpretive programs. Non-technical staff can learn the techniques, even those who have little imaging experience. The images produced can be shared with the public over the Internet.|
A Cultural Crossroads Through the Ages
Despite its rugged alpine terrain, Switzerland has always been home to many travelers and adventurers. Ancient settlements occupy virtually every valley that shelters a pass through the jagged Alps. For millennia, these villages and towns have seen all manner of adventurers, pilgrims, and conquerors pass through or stay for a while. Many of these trekkers left behind wonderful archaeological legacies in the form of secret coin hoards, stashes of beautiful ceramics, and other precious works of art.
Journey of Discovery
CHI researchers set off on their alpine expedition in Fall 2005 when they spent 14 days documenting 114 objects from 3 Swiss collections. CHI staff created spectacular 3D images of gleaming Greek, Celtic, and Roman coins, Celtic funerary ceramic animals, and bronze sculptures and jewelry.
For this project, CHI developed an automatic RTI capture dome. This system uses a digital SLR camera and fiber optic light source. The single fiber optic illuminator allows for precise filtering of the light allowing imaging of fragile light sensitive objects like ancient lead and wax document seals without damage. CHI volunteers Tim Lindholm and Michael Hyde deserve special recognition for their efforts in developing the RTI capture dome—a sleek device that travels well. CHI also captured the world's first multiview RTI data set.
Museum of Money
What better place than Switzerland to have a Musée Monétaire? Housed in an elegant Rumine Palace in Lausanne in the Swiss Canton of Vaud, the money museum has a numismatic collection of more than 100,000 coins made of gold, silver, and other metals. A large percentage of the coins came from the historic treasury of Savoy along with local hoards lost or buried by travelers from many eras. CHI spent several days in this stalwart repository documenting ancient coins selected by the Director, Dr. Anne Geiser.
Among the fascinating coin images captured with CHI techniques are a series of Celtic coins (circa 300 BCE). The Celtic versions of widely circulated Macedonian originals portray Philip II of Macedon, father of Alexander the Great, using elegant, stylized, abstract compositions.
All Roads Lead to Valais
The Canton of Valais has everything—fine wines, fabulous cheese and chocolate, and even the Matterhorn, one of Switzerland’s highest peaks. Valais also has a world-class archaeological collection partially housed in Martigny and renowned for its excellent Celtic, Roman, and Medieval artifacts from many excavations. The intrepid CHI explorers made images of bronze sculptures, incised ceramics, and a silver coin hoard. While they were capturing these images, they were also capturing valuable process history data.
Keeping Track of Data
A big advantage of CHI techniques is that they preserve all of the data and digital information collected during the imaging process. When they developed their methods, CHI researchers incorporated the actions feature in Adobe Photoshop software to record all image processing steps and the settings used for each image. Other files generated during the process retain light position settings, command line settings, and file conversion settings. These data, files, and settings are important pieces of the process because other scholars can use this information to replicate what CHI has done. The ability to reproduce CHI’s results contributes to the scientific validity of the process.
Sharing an Ancient Collection with the World
The final stop for the CHI expedition of Fall 2005 was the stellar collection maintained by the Congregation of the Grand St. Bernard. Perched in a perfect alpine valley and surrounded by sharp-edged mountain summits, the monastery was founded in the 11th century CE. The famed St. Bernard rescue dogs originated in this area. Over the centuries, many wayfarers passed through the valley and found shelter at the monastery and other structures. The collection grew through the years as antiquities, coins, documents, and seals were carefully saved for posterity. The monks excavated many sites in the region and preserved artifacts in their collection. The congregation also maintains a Hospice at the Simplon Pass, which is 2,000 feet lower than the Grand St. Bernard. Given the late time of year, the CHI team stayed and worked with the collection in the Simplon Hospice with archivist Jean-Pierre Voutaz.
Inspired to Experiment
CHI staff captured images of lead papal seals and Celtic ceramic jars shaped like a lion, rabbit, and bird. CHI researchers also used the fiber-optic dome device to capture image data for a very special item—a Bronze Age torque (neck piece) from 1700 BCE. The monks found this object with a skeleton at a grave site. The CHI imaging techniques revealed a delicate geometric pattern incised on the torque. The uniqueness of the neck piece inspired CHI to capture the first multiview RTI. The Torque was placed on a turntable and RTIs were captured every 30 degrees of rotation. In 2006, a new multiview RTI viewer was built by Tom Malzbender at HP Labs, that enables the torque to be turned to an area of interest and then viewed using reflection transformation. This process is described in the paper.
- SLR digital camera
- Laptop computer with remote camera control software and Adobe Photoshop
- Automatic object movie capture structure based on a programmable Seitz Phototechnik panorama stage with detachable vertical adjustment module (optional)
- Portable aluminum-frame lighting dome with fiber optic lighting array and mesh screen carrying case (optional)
The CHI software needed to create images and to view them is available free for non-commercial use (see the Downloads section of this site).Polynomial Texture Mapping (PTM)
Image-based representation of the appearance of a surface under varying lighting directions. PTM is an early form of Reflectance Transformation Imaging (RTI).PTM Object Movies (POM)
A synthesis of individual PTMs into an integrated, multi-viewpoint, interactive presentation that can be viewed on a computer and over the Web with free viewer software.POM Viewer
Movie viewer software that assembles PTM images into an interactive movie that can be viewed over the Web or downloaded and viewed on a computer.Reflectance Transformation Imaging (RTI)
Mathematical techniques to transform image reflection data to accommodate changing light directions and to enhance surface details. Developed for use with PTMs by Tom Malzbender and his colleagues at HP Labs.