Archaeological Computing Research Group

Ultraviolet RTI

March 24, 2015
by Eleni Kotoula

A painted and incised ceramic vessel was used as case study in an attempt to evaluate the efficiency of Reflected UV (UVR) RTI and UV induced visible fluorescence (UVF) RTI.

Gnathian skyphos from the University of Southampton Archaeological Collection

Gnathian skyphos from the University of Southampton Archaeological Collection

The Highlight RTI data capture took place at the archaeological imaging laboratory of the University of Southampton, using a UV-VIS-IR modified DSLR camera, adequate filters and lighting. The reflected UV-RTI datasets were captured with a UV transmitter and an IR barrier filter. The UV induced visible fluorescence RTI datasets were captured with an IR and an UV barrier filter.

The UV induced visible fluorescence image reveals the remains of conservation materials on the surface of the ceramic skyphos and the previous repairs, because of the visible fluorescence emission of common adhesives used. The UV induced visible fluorescence RTI enables the user to virtually move the radiation source around the object leading to numerous different visualizations. In that way the conservator can reach a better understanding about the morphology of the previous repairs.

Reflected UV-RTI offers the opportunity for enhanced examination of subtle surface variations; the remains of the conservation materials, the differentiations of the glaze due to its poor preservation and the salts’ efflorescence. The technique provided in a single file a combination of axial and UV imaging. It is notable that the axial positioning of radiation sources in reflected UV imaging is advantageous and is proposed for recording of scratches and smudges.


Gnathian skyphos, back side. RTI visualizations in default rendering mode, comparison of visible, infrared at 950nm, UV reflected and UV fluorescence (from left to right)

Gnathian skyphos, back side. RTI visualizations in default rendering mode, comparison of visible, infrared at 950nm, UV reflected and UV fluorescence (from left to right)

Gnathian skyphos, back side. Normal maps, comparison of visible, infrared at 950nm, UV fluorescence and reflected UV (from left to right).

Gnathian skyphos, back side. Normal maps, comparison of visible, infrared at 950nm, UV fluorescence and reflected UV (from left to right)

The synergy of RTI and UV imaging, results in an enhanced methodology for non-destructive examination and leads to different views of artefacts, which can be used for documentation, presentation, communication and research purposes.

UV-RTI visualization:

  • Emphasizes subtle variations in the outer layer that are not clear in the visible spectral area
  • Reveals episodes of the museum life of the artefact
  • Reveals manufacture evidence and decay relevant to varnish layer or glazes


Archaeology Day 2014 my day

Paul ReillyAugust 30, 2014
by Paul Reilly

Where did you say you left those epistemological cleavers and ontological chisels?

Where did you say you left those epistemological cleavers and ontological chisels?

July 11th, 2014 was this year’s designated Day of Archaeology, a day for any archaeologist to share some aspect of their working life with the world at large. Here are some of the things that were preoccupying me that day.

Early that morning, I walked down a mountain through olive groves, with the pre dawn breeze wafting me gently on, to catch a bus from the SE Cretan town of Makrigialos which took me to ancient and modern Irepetras, Europe’s most southerly port city, and from there onwards to Heraklion Airport from where I posted my Day of Archaeology blog. It was a beautiful scenic route, taking in sections of both of Crete’s impossibly sapphire-blue south and north coasts, and a pass though island’s eastern massifs, gorge riven, and pine forested, and of course ancient groves filled with contemporary olives. The shaded coolness of the air conditioned buses provided a stark contrast to the solar sintered landscapes through which the the bus wended its way. En route I passed by the Minoan impregnated places of Vasaliki, Gournia and Malia. The past endures in Crete. It’s persistent.

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Postcards from the field: Studying the Neolithic figurines from Koutroulou Magoula, Greece

Konstantinos PapadopoulosAugust 21, 2014
by Konstantinos Papadopoulos

Clay Neolithic figurines are some of the most enigmatic archaeological objects, which depict in a miniature form humans, animals, other anthropomorphic or zoomorphic beings, and often hybrid or indeterminate entities. Figurines have excited scholarly and public imagination, and have given rise to diverse interpretations. The assemblage from Koutroulou Magoula, a Middle Neolithic site – 5800-5300 BC – in central Greece (excavated under the co-direction of Prof. Yannis Hamilakis – University of Southampton/British School at Athens and Dr Kyparissi-Apostolika – Greek Ministry of Culture), offers a unique opportunity to revolutionise the way we study and understand prehistoric figurines.

The video presents the project ‘Corporeal engagements with clay’ (funded by the British Academy/ directed by Prof. Y. Hamilakis) showing aspects of our work in recording, visualising and replicating the figurines from Koutroulou Magoula by using a tailor-made database, as well as drawing, photography, photogrammetry, laser scanning, reflectance transformation imaging and 3D printing.


True Gigapixel RTI

James MilesAugust 5, 2014
by James Miles

The ACRG has always been an integral part within the recent development of RTI. ACRG’s involvement began with the AHRC funded RTISAD project where we piloted the technique on inscribed ancient documents and archaeological artefacts. We likewise raised awareness of RTI in research and public communities in the UK. This has since led on to several organised community days such as the one held at Winchester Cathedral and the Re-reading the British Memorial community driven project that focuses on churches. The project has completed a number of these community days and is led by ACRG members Gareth Beale and Nicole Beale.

Since the RTISAD project our understanding of the technique has greatly changed. As new technology becomes available we are adapting our methodology to create new research avenues that not only help our department stand out but it also helps the wider community. Examples of this can be seen in the work completed by Eleni Kotoula who has created different methodological approaches in Microscopic RTI, Multispectral RTI and Transmitted RTI. Eleni, having come from a conservation background, saw potential in the technology within her own studies and many other members of ACRG are now utilising these methods as general practice within their own investigations. Further developments can be seen in the work completed by David Selmo who created the first underwater RTI dataset. He saw the potential that it had within maritime studies, developed the technique and then tested the methodology in open waters. Read the rest of this entry →

Update on the Hoa Hakananai’a Statue

James MilesAugust 1, 2014
by James Miles

In 2012 ACRG members, James Miles and Hembo Pagi, completed a series of RTI captures and a photogrammetry model of the Easter Island Statue, Hoa Hakananai’a, which is currently housed in the British Museum. Since then, in collaboration with Mike Pitts, we have examined the results of these RTI files and compared them with the photogrammetry model. A brief discussion of this work can be seen in a previous blog post. The methodology that we utilised allowed for a full analysis of the statue that has previously been impossible. It allowed us to examine the RTI files in fine detail through the changing surface detail identified through the raking light and rendering modes. Where we thought we had identified something important we could then see if it existed in the 3D model. This comparison then allowed for a combination of the subtle 2D differences in the RTI to be mapped and compared to the 3D surface differences in the virtual replica of the model. Through this we were able to clear up some of the often ambiguous interpretations of the petroglyphs. More on our results and methodological approach can be seen in our recently published Antiquity paper, our Antiquaries Journal paper, Mike’s paper in the Rapa Nui Journal and our soon to be published paper in the Proceedings of the 41st Computer Applications and Quantitative Methods in Archaeology Conference. The work has also gained a lot of public interest and our research features in recent online publications which are a Google search away.

Since these publications I have been working on ways, as part of our initial research aims, at producing online versions of the datasets, where users can view and manipulate the records that we have. This will allow different people, with different backgrounds to come to their own conclusions. Part of this blog post is to make available for the first time, the RTI files that were produced within our investigations. At Southampton we are working on creating a newer and better online RTI viewer, but at the minute we are left with having to produce low resolution datasets for online use. The following then is a severely reduced RTI dataset but the results are still evident none the less. The RTI files have been separated into five different sections, one of the front and four of the back (with a slight overlap) to allow for a greater understanding. Read the rest of this entry →

Annotating RTI data in 3d and 2d

May 17, 2014
by Graeme Earl

I’ve been talking to a lot people in recent months about annotation frameworks for RTI and today’s introduction to the #rodeimagingevent (see Hembo’s blog post) has crystalised some of these. I was talking to @kathrynpiquette about annotation and I also tweeted a query to @iipimage about it. @portableant suggested annotorious (something that I know our current MSc student Vassilis Valergas has been examining) and also openCanvas was suggested. Also @aboutgeo mentioned the freeform extension to annotorious developed by @portableant. We started talking about the idea of this being a geospatial problem rather than an image annotation problem and whether frameworks in online GIS were more advanced. Read the rest of this entry →

Papyrus RTI case study

May 15, 2014
by Eleni Kotoula

The Derveni tombs discovered in 1962 close to Thessaloniki in North Greece are considered one of the most significant archaeological sites in northern Greece because of their numerous rich grave offerings and their important location in the ancient Mygdonian city of Lete, on the pass of Via Egnatia. The cemetery comprises seven graves, and according to the excavation publication dates to 320–290 BC. One of the most remarkable finds of the Derveni Tombs is a papyrus roll, discovered in the remains of a funeral pyre above tomb A, a cist grave full of bronze and clay pots, vessels, jewellery and small objects (Themelis & Touratsoglou, 1997). The Derveni Papyrus fragments examined are preserved sandwiched between two sheets of glass. As a result the material integrity is safeguarded and the undesirable material deterioration due to handling is limited. At the same time, the glass mount poses a barrier in the study of the papyrus and affects visual analysis negatively. One of the most crucial features for the correct perception of information revealed from visual analysis is the perception of three-dimensionality, which in case of the Derveni papyrus is limited because of the glass mount. Another problem is the completely covering or the back side of the fragments, due to the backing material, which limits considerably the study of the material aspects of the papyrus.
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Imaging Event/Hackathon

Hembo PagiMay 12, 2014
by Hembo Pagi

Few days to go to Rode Imaging Event where ACRG will be represent on power of three: Graeme Earl, James Miles and me. List of presenters at the seminar and workshop day include specialist with different expertise: multispectral imaging, 3D data acquisition and processing and theoretical approach.

Hackathon weekend is supported by Garage48, people specialised in hackathons and helping start-ups. There are several ideas for the hackathon prepared by us but I am sure there will be more ideas that we can focus on such a short event.

ACRG has been supporting the event with some equipment and software to let people see and play with stuff they might not have otherwise access to.

ACRH Gigapan in action at St Nicholas church, Tallinn

ACRH Gigapan in action at St Nicholas church, Tallinn

Modelling Complexity

Iza RomanowskaApril 17, 2014
by Iza Romanowska

A Fractal Flame

A Fractal Flame

Complexity has become a new paradigm in the hard sciences in the 90s and since then it has been slowly dripping into the social sciences and humanities. It works on the premises that many systems are complex in structure, i.e. their numerous individual parts interact with each other in a non-linear way producing phenomena which cannot be easily predicted solely on the basis of their characteristics. Think of the brain: if you were given a few neurons to research it would probably not be your first guess that those little buggers create emotions. Think of the stock exchange: the behaviour of any one of the stock brokers (buy when you think it’s gonna go up and sell when it’s going down) is not a great predictor of the long term trends or crashes, which, nevertheless, follow quite a repetitive pattern. Now think archaeology: we work on human societies whose complexity arising from simple human interactions is overwhelming and produced on many levels. When do people decide to migrate? Why certain trends catch up while others don’t? How do stratified societies develop and why do they collapse? The list of questions complexity science can help us with is truly endless and touches on the very core of what archaeology is all about.

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Burying the Digital

April 3, 2014
by Graeme Earl

Clay tablet (wikipedia)

Clay tablet (wikipedia)

I am at Museums and the Web this week in Baltimore. I was sat next to @trinkermedia and we were talking enthusiastically about  the physical, tangible and the interactive digital (as usual). Over the last few years we have been digitising very large collections of cuneiform tablets and are mid way through developing an open source Reflectance Transformation Imaging web renderer that will allow interaction with these on mobile devices and desktops. The plan is that we will deploy these via tablets and phones of various form factors in order that the gyroscope and the lighting hemisphere captured from a front camera can be used to provide a sense of placing the digital tablet in its physical surroundings more completely. So, my aim is that, for example, in a room with low lighting captured from the phone the main directional light source vector will be identified from the maximum brightness in a photograph from the front camera and the RTI relighting intensity will be scaled to match that brightness. Once set this orientation should allow the gyroscope to link movement of the tablet to the space within which the movement is happening, and in turn relight the virtual object in a contextual way. We still have a way to go but we have a good handle on the methods to employ. So, watch this space.

But back to #mw2014. Javier and I were talking about his work to repurpose Linked Data and also his interest in interactive forms. I have been reflecting on the continuing power of the physical artefact in my life as I finalise the @UoSFLPortus MOOC. I want the MOOC to provide digital experiences of Portus and artefacts, but I also want to encourage the students on the MOOC to make their own interactive objects (more to follow on this soon via the Portus MOOC blog) and also to visit museums collections near where to they live to provide another form of engagement, and finally to think how accessible, touchable objects in the home could stand in for inaccessible, curated artefacts. (We now have the beautiful work of Eric Brockmeyer to stimulate us!). The plan is for the Archaeology of Portus MOOC to have a subsidiary archaeological computing and digital museums flavour, via the blog. So we would be excited to work with others on this in the coming months.

Anyway, all this made me think about the other project that is big in my head at the moment – the @Ahrcrti project focused on the RTI viewer. In the last few weeks we have been doing some work on RTI archiving in collaboration with Cultural Heritage Imaging and @ads_update and @UniSotonLibrary – the plan is to enable an easy mechanism to embed RTI repository content in blogs and websites and to link specific annotations via DOIs so that threaded citation and conversation around the RTI interpretations can grow. Again, more on this soon.

The question here is, could we physically instantiate the RTI of cuneiforms so that a physical tablet might survive as the carrier for the information long into the future? I am fascinated by the possibility of chance discovery of the tablet, and the intersection of the tablet with a repository. If nothing else it foregrounds the 10 or 20 years quoted in many archiving strategies for research data. I could do the same for information from Portus, perhaps encoding a brick stamp in similar ways. If I drop a rugged tablet into the foundations of the Palazzo Imperiale it may not be discovered for centuries. How long would the device survive? And what connections would the device be able to make in the future? What should we encode on the device. alongside the object data?