Images of Roman Imperial Denarii: A Curated Data Set for the Evaluation of Computer Vision Algorithms Applied to Ancient Numismatics, and an Overview of Challenges in the Field (Version 2, Revised)
|Reviewer 1 Alan M. Stahl Princeton University||Reviewer 2 Christoph Hartmann Research assistant, Technical University of Munich, Walther-Meissner-Strasse 4, 85748 Garching, Germany||Reviewer 3 Eleni Fragaki Leiden University|
Approved with revisions
Approved with revisions
Approved with revisions
|Not approved||Approved||Approved with revisions|
Arandjelović, O.; Zachariou, M. Images of Roman Imperial Denarii: A Curated Data Set for the Evaluation of Computer Vision Algorithms Applied to Ancient Numismatics, and an Overview of Challenges in the Field. Sci 2020, 2, 47.
Arandjelović O, Zachariou M. Images of Roman Imperial Denarii: A Curated Data Set for the Evaluation of Computer Vision Algorithms Applied to Ancient Numismatics, and an Overview of Challenges in the Field. Sci. 2020; 2(2):47.Chicago/Turabian Style
Arandjelović, Ognjen; Zachariou, Marios. 2020. "Images of Roman Imperial Denarii: A Curated Data Set for the Evaluation of Computer Vision Algorithms Applied to Ancient Numismatics, and an Overview of Challenges in the Field." Sci 2, no. 2: 47.
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p. 2. "ancient numismatics, i.e., the study of ancient (mostly Roman) currency," - actually, most ancient numismatic research is carried out on Greek coins, whose attributions depend on die and hoard study, unlike Roman imperial coins, whose identification is often obvious from their legends.
2.1 Terminology. This is incorrect use of the word 'type' in a numismatic context. In numismatics, 'type' refers only to the image on the face of the coin. I think the authors are confusing the common meaning of 'type' with the numismatic one, and should use 'issue' for what they term type. This error is repeated throughout the article.
2.3 Die matching. Die study is the basic methodology of most numismatic study, and is vital for discussions of chronology, mint organization, and size of emissions. The authors are incorrect in saying that it is an unexplored challenge in the realm of ancient coin analysis -- in fact it is the aspect that is receiving the most attention from numismatic scholars; a case in point is the long-standing work on automated die identification for the fifth-century tetradrachms of Athens, being undertaken by Dr. Peter Van Alfen of the American Numismatic Society.
2.4 3-D scanning. At Princeton, we have a long-running project on the die analysis of didrachms of Taranto based on 3-D scans performed on our extensive collection, which includes many examples of coins listed as die-linked or die-pairs in the Fischer-Bossert corpus. We have not yet received publishable results due to such problems as registration and the sheer mass of data to be analyzed. We do believe that machine learning is a valuable direction to move in.
3. Degree of wear. We have found that factors other than the degree of wear of specimens pose significant obstacles to machine approaches to coin analysis and identification - die wear in terms of lowered relief, die wear in terms of spreading and cracking of dies, differences in the centering of dies for striking, differences in the angle of the blow used in striking. And, the reason we decided to work with 3-D scans of coins in our collection, is the vast series of problems introduced by 2-dimensional photography using differential lighting, lenses, and digital transfer to web protocols.
3.1 Denarii. The choice of denarii is sound, but attention should be paid to recent work by Butcher and Ponting showing the degree to which the composition of denarii in the Roman Empire varied considerably over time.
Table 1. This should be presented in chronological rather than alphabetical order.
4. I fail to see any explanation of what degree or area of analytical knowledge is gained by the consideration of the degree of preservation of studied examples in the application of computer-assisted numismatic study. Basically this article introduces one of many factors to be taken into account in machine-assisted numismatic analysis but doesn't explain its role in such analysis or give examples of results obtained through it.
Response to Reviewer 1Sent on 14 Jul 2020 by Ognjen Arandjelovic
Research assistant, Technical University of Munich, Walther-Meissner-Strasse 4, 85748 Garching, Germany
The Paper is well written and tackles an interesting target. My only siggestion is mabey to include also a connection to the field of experimental numismatics (see for example Experimental analysis of Roman coin minting. Journal of Archaeological Science: Reports 25, 2019, 498-506), since the proposed methods would be also beneficial for researchers in this field.
Response to Reviewer 2Sent on 14 Jul 2020 by Ognjen Arandjelovic
The topic of this paper is very interesting and the suggested research has definitely a strong potential. However, both the content and the presentation should be revised in order to reach the aims of the study.
Even if there are no previous attempts to provide an overview of the applications of machine learning in the field of numismatics, the related literature needs to be summarized and evaluated in the introduction.
The enumeration and discussion of the challenges in this field has to take more appropriately into account the concerns of specialists in ancient currencies and the exact meaning of the terminology must be reexamined and respected. This part of the article should rather focus on technical aspects and describe the specific tools and methods that can be used to address these questions.
The idea to collect a curated set of coins in various stated of preservation has an obvious advantage from an archaeological point of of view. However, the exact technical implications of this choice could be more extensively analyzed. If the readership is supposed to include experts in a numismatics and hobby collectors the technological parts must be formulated in a more accessible and explicative way. Even if the text is intended only for computer scientists, the parts dealing with numismatics should be reconsidered.
Response to Reviewer 3Sent on 14 Jul 2020 by Ognjen Arandjelovic
Chargé de Recherche classe normale, IRAMAT-CRP2A (CNRS, UMR 5060), Bordeaux
The article presents the latest considerations on the computer vision developments on the field of numismatics.
I personally doubt the interest of such a dataset which is obviously directed towards the commercial side of numismatics. The databases of major collections (British Museum London, BnF Paris, Münzkabinett Berlin, American Numismatic Society New York), as portals on specific coinages (RPC online, RIC online, Pella, Seleucid coins online, etc…), have florished in the past years presenting large datasets available with good quality images and curated datasets. The classification by wear is mostly used for commercial purposes for obvious financial matters even though some scholars have been trying to use them (See J.-M. Doyen, L'indice d'usure des monnaies en tant que substitut aux indices de fréquence, in S. Krmnicek & J. Chameroy (eds), Money Matters, Coin finds and ancient coin use, Bonn, 2019, p. 21-30).
The distorted version of the work on computer analysis focused on Roman numismatics shown in this article mostly forget that the majority of the work done on computer die recognition have been made on Greek and Celtic coins. Die studies have been massively used in Greek numismatics because datasets are more manageable than the Roman ones for which corpora of most issues make them impossible to study with a die analysis.
As the article is entitled “overview of challenges in the field”, it would be therefore appreciated to enlarge the references for the different aspects of Ancient Numismatics.
p. 2: ancient numismatics cannot be considered as “mostly Roman”
p. 2: “An important consideration in numismatics regards the condition of a particular coin”. This is true only for the commercial part of the numismatics, not for the research part. I do not see what this sort of consideration “the price of the coin, and thus its affordability as well as its investment potential, are greatly affected: The cost of the same type can vary by 1–2 orders of magnitude” help the debate in the article.
p. 6:” type matching as probably the most important and pervasive problem”. It is true for a commercial use. The interest of academic relies more certainly on die matches.
p. 7: “To the best of our knowledge, die matching remains an entirely unexplored challenge in the realm of automated ancient coin analysis”. This is suprising to read. Efforts have been made since the 1970’s to be able to perform automatic die studies. Once again, the limited view of the article on Ancient Roman numismatics eliminates most of the research held in Greek and Celtic numismatics, which are more advanced than Roman numismatics on Die analysis. The bibliography would be too long to provide here. For the latest : Taylor, Z. M., and van Alfen, P. Coins and computation: New developments in the computer-aided die study. https://www.youtube.com/watch?v=wF6aZdhc0wg, 2020. ANS Money Talks: Numismatics Conversations ; van Alfen, P. The computer aided die studies program. http://numismatics.org/pocketchange/cads/, 2017. Accessed: April 27, 2020 ; Sofiane Horache, François Goulette, Jean-Emmanuel Deschaud, Thierry Lejars, Katherine Gruel. AUTOMATIC CLUSTERING OF CELTIC COINS BASED ON 3D POINT CLOUD PATTERN ANALYSIS. 2020. ⟨hal-02559952⟩.
p. 9: “the difficulty of obtaining a curated data set; hence, our present effort and contribution.” Databases of major collections are now online. Curators of each institutions have supervised the information in these databases. Nowadays, hundreds of thousands of coins are available through these institutions and even reunited in portals, offering major curated datasets.