Hyperspectral Imaging of the Orpheus Relief
Jeff Speakman and Tina Salguero
Surface Optics Corporation recently brought a state-of-the-art SOC710 hyperspectral imaging camera to the University of Georgia for use in the Orpheus Relief Project. SOC President Dr. James Jafolla and Sales Engineer Mike Zemlan, based in San Diego, CA, spent two days in Athens to perform data collection and lecture about their area of specialty: non-contact spectral imaging techniques available for historical, conservation, and archaeological studies as well as geological mapping and environmental monitoring.
What is hyperspectral imaging? Hyperspectral imaging is an analytical technique that measures the reflectance properties of materials across a broad range of the electromagnetic spectrum, beyond what the human eye can see. By collecting and analyzing data from the ultraviolet, visible, and near-infrared regions, we can map areas that contain different materials, and also get spectral fingerprints that can be used to discriminate between materials that may look similar at first glance. As shown in the image below, hyperspectral imaging provided a map of remnant pigment on the Orpheus relief (labeled in red by the camera’s software) that all has the same reflectance profile.
In addition to scanning the relief itself, project researchers used the SOC710 to collect data on reference samples. One example is Egyptian blue, one of the earliest synthetic pigments. Ancient Greek and Roman artisans commonly used Egyptian Blue to decorate marble sculpture, and remnants of this pigment could be one of the materials remaining on the Orpheus sculpture. The data on reference samples of Egyptian blue will help identify whether its signature is present in hyperspectral imaging maps.