Earlier this year, while I was still in Edinburgh, one of my undergraduate professors visited the university to present a lecture on the Missorium of Aspar, pictured above. Generally speaking, missoria were large silver plates issued by emperors or other notables to commemorate significant events. The most famous example of this type of dish is the Missorium of Theodosius, which was likely issued to celebrate the tenth anniversary of the accession of Theodosius I in AD 388.
The bulk of Dr. Bevan’s lecture dealt with the various details of the Missorium of Aspar, their interpretation, and their historical context, yet in the final ten or fifteen minutes he also discussed the imaging technique he used in his analysis. As you can see from the image of the missorium above, the major features such as the seated figures of Aspar and his son or the text running along the edge of the dish are clearly visible. The image, however, is a photograph published 70 years ago now, and it is difficult to see some of the more subtle details of the metalwork with the naked eye. Enter RTI.
Reflectance Transformation Imaging (RTI) is an imaging method used to produce a three-dimensional digital rendering of a surface – in this instance, of the Missorium of Aspar. This is accomplished through taking a series of photographs of the surface with varying light positions and feeding those images into a piece of software, which subsequently produces the 3-D rendering.* The resulting image can then be manipulated and rotated in an RTI viewer to simulate different lighting conditions, thereby revealing subtle details of the surface texture. Many professional uses of the technique employ a dome-shaped lighting array to optimise the results, but it is ultimately a fairly simple process that can be accomplished with a digital camera, a light source, and the appropriate software.
I have been lucky enough to work with Dr. Bevan on a few occasions using RTI and have consequently seen the benefits of such an approach. During his lecture in Edinburgh, however, I could tell there were a few people in the audience who were more sceptical. Perhaps there are even some of you reading this now who are wondering “Okay, great, so what?” To these people, I would like to present Dr. Jacob Dahl. A member of the Faculty of Oriental Studies at the University of Oxford, Dr. Dahl has been working on deciphering the proto-Elamite language for over ten years and is now using RTI in his research.
I must admit, I was very excited by this news. The proto-Elamite script is currently the oldest undeciphered language from the ancient Near East, but the previous published images of the 1600 clay tablets bearing the script are no more than hand-drawn pictures of a rather low standard. Dr. Dahl’s use of RTI, therefore, represents a major improvement in not only image quality, but also in the method of analysis. He is currently working to produce high-quality images of the tablets located at the Louvre Museum and has even published them online to encourage the public to get involved with the decipherment.
This is the point at which my excitement ebbed a little though. The use of crowdsourcing in this case is certainly helpful in the identification of patterns which would help decipher the script, and the high-quality images are a major improvement over the previous drawings, but I feel Dr. Dahl could have gone even further; as far as I have been able to see, at no point in the public digital library does Dr. Dahl provide the actual RTI files themselves. These files are relatively small in size and do not take much processing power to manipulate, thereby making them accessible to most people with a computer – all that is needed is a piece of software that can be downloaded for free. In limiting the digital library to two-dimensional images (of whatever quality), the problem of subtle details seen above with the Misorium of Aspar arises again. Thus, the public may not be able to identify the same level of detail as would be otherwise available, and which may subsequently complicate the crowdsourcing endeavour.
The point of this post, then, is to demonstrate there are practical applications for the theoretical or experimental methodology tossed around by academics. Sometimes these applications take a while to manifest, especially with complicated or expensive techniques, but the benefits of moving forward with these techniques can also sometimes be as exciting as deciphering a whole language from five thousand years ago.
* I have simplified this explanation somewhat so readers don’t get lost in the details. If you are interested in a full explanation, however, this Cultural Heritage Imaging page has plenty of information.
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