A relatively inexpensive imaging system developed by researchers in Denmark is giving archaeologists additional ways to distinguish buried deposits before they remove them. The prototype, known as LEDMSI, illuminates excavation surfaces with LEDs operating at 16 wavelengths, spanning near-ultraviolet, visible and near-infrared light.
The system was developed by Aarhus University and Moesgaard Museum and tested at Sorte Muld, an archaeologically rich Iron Age site on Bornholm. The site contains more than a meter of dark deposits formed through centuries of human activity. Many of its layers are thin, irregular and visually similar, making their boundaries difficult to identify in ordinary photographs.
LEDMSI repeatedly photographed the same soil section under the different wavelengths. Researchers then applied statistical analysis to the combined images, enhancing differences in the way materials absorbed or reflected light. According to the report from Phys.org Archaeology, the resulting images revealed changes that were difficult to see with the naked eye, including features that may represent separate deposits.
One feature could be an earlier ground surface and possibly a pause in activity at the site. The researchers emphasized that this interpretation still requires confirmation. The system’s immediate value, they said, is its ability to direct attention toward differences that might otherwise go unnoticed.
The imaging also produced a potential advantage for locating bone. Small fragments fluoresced under ultraviolet illumination and became easier to distinguish from the surrounding soil. The study found that useful information could be collected without the optical filters normally used in fluorescence photography, simplifying the equipment. The researchers did not demonstrate that LEDMSI can identify the best samples for ancient DNA analysis, although fluorescence in archaeological bone has previously been associated with collagen preservation.
The prototype is estimated by the researchers to cost roughly 20 times less than hyperspectral imaging systems used for similar archaeological applications. A second-generation version, equipped with a better camera and two LED units, has since been tested at Fredbjerg in northern Jutland, a cemetery dating to the late Viking Age and early Christian period. There, preservation is poor and some graves are visible mainly as faint soil shadows. Multispectral images helped the team choose locations for additional sampling.
The newer system captures its image series in about 30 seconds, compared with up to five minutes for the initial prototype. The researchers are working toward near-immediate processing in the field and eventually hope to use machine-learning software to help distinguish different materials, while keeping archaeological judgment central to interpretation.
