As we have mentioned in previous entries of this blog, earlier this year we worked in collaboration with Inchinnan Historical Interest Group. With a great interest in digital technologies, we were commissioned to use different techniques to obtain as much information as possible from the local heritage related to the lost church of All Hallows. This has recently translated in the discovery of new information related to a carved stone.
To better observe the carvings on a group of ten stones from the site of All Hallows, as part of the ‘St Coval to All Hallows’ archaeological project, we used two digital heritage techniques. The first of them was Photogrammetry, the creation of metric 3D models through photography. The second technique was RTI (Reflectance Transformation Imaging), a multi image technique which makes it possible to illuminate a surface from different angles. This makes it easier to understand and read the carvings on stone that, as on the stones from Inchinnan, have been eroded. In this case, the RTI images were created from the photogrammetric models, by removing their texture, and creating a digital vault with 93 lights to create 93 images, each with a different lighting.
The group of stones was believed to date from the 12th to 17th century, judging by the carvings visible. However, when Megan Kasten (PhD student from the University of Glasgow) recently analysed the 3D models and RTI files, she recognised in one of them, Stone 5, interlaced decoration and the remains of a cross that indicated it was not only early medieval, but that it belonged to the ‘Govan School’ of carving. The stone’s other carvings, carved letters, which had suggested a later chronology, would be the result of a later reuse of the stone as a grave slab.
This is just an example of the possibilities methods such as RTI and Photogrammetry bring to the study of cultural heritage.
To learn more about the ‘St Conval to All Hallows’ project and Inchinnan Historical Interest Group, you can visit their website. To keep updated on the secrets we unveil using digital heritage, you can join our newsletter. And for examples of other projects involving these and other techniques, visit the Spectrum Heritage website.