Ultraviolet RTI

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. 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 […]

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

 

Night with Gertrude. And Victor.

Updated Dec 9th: Video added. Gertrude is an old lady. About 600 years old. She is one of the wooden statues at the high altar in St. Nicholas’ Church, Tallinn. Gertrude is reviled to the public three times a year. Rest of the time she and other status are hidden behind the massive altar wings. […]

Updated Dec 9th: Video added.

Rode altar Nigulistes

Gertrude with high altar behind

Gertrude is an old lady. About 600 years old. She is one of the wooden statues at the high altar in St. Nicholas’ Church, Tallinn. Gertrude is reviled to the public three times a year. Rest of the time she and other status are hidden behind the massive altar wings. Those altar wings are covered with medieval comic strip about life of St. Nicholas and St. Victor. Altar is by Hermen Rode, artist from Lübeck, finished around 1481 AD.

I spent few hours with Gertrude and Victor, and nice people from Art Museum of Estonia: conservator Hilkka, art historian Mari-Liis and MA student Kaisa-Piia from Estonain Academy of Art. I had with me RTI-kit and multispectral camera.

Rode altar

Art historian Mari-Liis and conservator Hilkka from the Art Museum of Estonia

RTI was a new technique to try on altar and it came out very nicely. You can see some screenshots here from the results. This was just a small test but the plans are much bigger.

With multispectral camera we took photos of Decapitation of Victor. And we reviled some 600 years old secrets. Will write about that an other time. The plan is to document both altar wings using IR photography.

Hopefully collaboration with Art Museum of Estonia will involve some other ACRG members in near future. Very exiting times.

Example RTI views (click to change)

The voice of Easter Island in the British Museum

Over the past year myself, Hembo Pagi and Graeme Earl from the ACRG have been working with Mike Pitts, editor of the British Archaeology Journal, on the Hoa Hakananai’a statue at the British Museum. The work included the production of a virtual model, through photogrammetry and a series of Reflectance Transformation Images to study the […]

Over the past year myself, Hembo Pagi and Graeme Earl from the ACRG have been working with Mike Pitts, editor of the British Archaeology Journal, on the Hoa Hakananai’a statue at the British Museum. The work included the production of a virtual model, through photogrammetry and a series of Reflectance Transformation Images to study the petroglyphs found on the statue. The analysis of this work is ongoing but we are happy to announce that an article entitled “The story of Hoa Hakananai’a” appeared in British Archaeology issue 130 pages 24 -31.

You can view the article online at British Archaeology Magazine website with some of the results found below. Research papers are currently in preparation for peer review of the completed work and an introduction to the project was given by myself at the Computer Applications and Quantitative Method in Archaeology 2013 conference in Perth, Australia.

More about the article on Mike Pitt’s Blog

Example RTI views (click to change)

Animation of the photogramnetry work

3D model in GrabCAD

View it with GrabCAD viewer

Late Bronze Age Stelae, Craftspeople and Digital Technologies: Some Recent Explorations

Reflectance Transformation Imaging (RTI) is revealing itself as a very powerful tool to examine prehistoric rock art. Through the application of different filters and the manipulation of the incidence of light, RTI provides an enhanced visual experience of the micro-topography of engraved stones, enabling the detection of subtle details that are difficult, at times impossible, […]

Reflectance Transformation Imaging (RTI) is revealing itself as a very powerful tool to examine prehistoric rock art. Through the application of different filters and the manipulation of the incidence of light, RTI provides an enhanced visual experience of the micro-topography of engraved stones, enabling the detection of subtle details that are difficult, at times impossible, to be seen through other recording techniques. In our own research, the application of RTI is providing us with valuable information about the craftspeople and the techniques involved in the making of a very special type of prehistoric rock art: Iberian Late Bronze Age stelae (see also previous posts: “RTI shedding new light on Iberian Late Bronze Age stelae” and “RTI & the Late Bronze Age stela of Mirasiviene (Sevilla, Spain)”).

** Detail of the stela of Almadén de la Plata 2 (Almadén de la Plata, Seville). When you click on the image, without RTI enhancement, you will see one of the multiple possible images produced by applying the RTI specular enhancement filter.

Late Bronze Age decorated stelae (c. 1425/1260-800/750 cal BCE) are very abundant in some regions of the Iberian Peninsula. Despite of a long research tradition dedicated to the subject, there are still relevant questions that remain unexplored. One of these is related to the manufacture of these beautiful stones. These stones depict, among others, people, shields, weapons, mirrors and chariots, elements that are usually organized on the surface of the stone following broadly distributed conventions. The engraving of some of these images required skillful hands, for at times the selected stones were specially hard and the tools employed were, most probably, lithic. Iron tools were still not accessible to most Iberian communities at the time, and the available metallic tools, made of bronze or arsenic copper, were too weak for stone working.

Precisely, one of the questions we are trying to elucidate through our research here at Southampton, David Wheatley and I, in collaboration with Leonardo García Sanjuán (University of Seville), is to which extent these engravings were made by itinerant or local craftspeople, and the degree to which rock engraving was a specialized activity. These are, of course, difficult questions and it will be extremely difficult, if not impossible, to provide conclusive answers. Nonetheless, our preliminary research has provided some relevant results that suggest the interesting potential of this line of inquiry if we explore it further.

Our preliminary approach to the subject has included the application of RTI to undertake a comparative analysis of the engraving techniques employed on three Late Bronze Age stelae. Two of these stelae, Setefilla and Mirasiviene (Lora del Río, Seville), were found in nearby locations, only 3 km apart, and display very similar iconographies. The third one, Almadén de la Plata 2 (Almadén de la Plata, Seville), was found 40 km away and displays a distinct, but still formally related, iconography. The three of them may be broadly dated to the same phase, between c. 1200 and 800/750 cal. BCE.

** Detail of the shield of the stela of Mirasiviene (Lora del Río, Seville). When you click on the image, without RTI enhancement, you will see one of the multiple possible images produced by applying the RTI specular enhancement filter.

The preliminary results could not be more interesting, for each of these stelae seem to have been engraved with different ‘packages’ of engraving techniques. If you click on these images, you will see different details that are more clearly seen through RTI filters, in this case the ‘specular enhancement’ filter. The images resulting from the application of varied RTI filters provide ample information to characterize the techniques employed in the engraving of each one of these stelae. You will see, for instance, that whereas the shield of the stela of Mirasiviene has been carefully carved with pecking and abrading, leaving a U shaped section, the shield of Setefilla seems to have been elaborated by less skilled hands, through less defined and more dispersed pecking. Finally, the stela of Almadén 2 provides an alternative to these two previous cases, as the engraving seems to have entailed a combination of pecking, incision and abrading, producing a V-shaped section.

** Detail of the shield of the stela of Setefilla (Lora del Río, Seville). When you click on the image, without RTI enhancement, you will see one of the multiple possible images produced by applying the RTI specular enhancement filter.

As you might have already considered at this point, this initial exploration suggests the possibility that Late Bronze Age stelae were crafted by different engravers with variable and locally rooted knowledge and skills, that is, following local engraving traditions. Now, the question that remains unanswered is the ways through which the iconographic conventions displayed by stelae were ‘disseminated’ and became ‘supra-regional’. Many of the depicted objects (i.e. shields or chariots) are still not known in the archaeological record of the Iberian Peninsula, and when they are represented on stelae, they follow more or less strict representational patterns. In this context, maybe we should consider that certain images, possibly inspiring this kind of representations, could have circulated through the movement of people and things in motion, either as mental templates or as materialized representations on perishable materials. More soon to come….

David Wheatley and I did the RTI of the stela of Mirasiviene during our fieldwork at the site last September. I would like to, very specially, thank James Miles, PhD student at the ACRG and Hembo Pagi for their training in making RTIs and also Víctor Rodríguez Zamora, Master student of the University of Seville, who helped me capturing the images needed to build the RTIs of the stelae of Setefilla and Almadén de la Plata last February. We are also very grateful to Concepción San Martín, director of the Archaeological Museum of Seville, and Pablo Quesada, curator of the museum, for their invaluable support while undertaking our image capturing sessions in the museum.

Winchester Cathedral RTI Community Day

On the 1st February I hosted a community RTI (Reflectance transformation imaging) day at Winchester Cathedral. The day was based around the introduction of this useful technique to the Cathedral guides, the Master students based in the computing research group and the lifelong learning students that have taken recent evening classes at the University. It […]

On the 1st February I hosted a community RTI (Reflectance transformation imaging) day at Winchester Cathedral. The day was based around the introduction of this useful technique to the Cathedral guides, the Master students based in the computing research group and the lifelong learning students that have taken recent evening classes at the University. It was very much a hands on experience where groups of individuals were taken by myself, Hembo Pagi, Nicole Beale and Gareth Beale and shown how to correctly capture objects of interest. The cathedral was chosen as a suitable location to host this event, due partly to the close links that I have established through my PhD research and partly through the wealth of available objects that could be recorded.

The day began by introducing everyone to the technique through a powerpoint highlighting the recent work that research group has completed using RTI. The volunteers were then separated into manageable groups and taken to the cathedral where a range of objects were recorded, including graffiti and ledger stones. The ledger stones were of high importance to some of the guides, who after years of studying them, could still not fully read some of the inscriptions present.

Nicole and her group capturing one of the ledger stones in the cathedral

Matthew and Marta capturing a RTI of some graffiti on the Gardiner Chantry

Hembo showing how to capture a RTI with his group

Individual snapshots of the results have been taken and can be seen below. The first image of the data presents the RTI before any manipulation of the light takes place, with the second image showing the RTI results. To see these results simply click on an interactive image of interest

Gareth

Hembo

James

Nicole

RTI & the Late Bronze Age stela of Mirasiviene

This Late Bronze Age (LBA) stela was found many years ago in a country-estate located in the Guadalquivir Valley (South Spain). Last September David Wheatley (University of Southampton), Leonardo García Sanjuán (University of Seville) and I have conducted fieldwork on the site where it was found (see also: previous post). We have also applied advanced […]

This Late Bronze Age (LBA) stela was found many years ago in a country-estate located in the Guadalquivir Valley (South Spain). Last September David Wheatley (University of Southampton), Leonardo García Sanjuán (University of Seville) and I have conducted fieldwork on the site where it was found (see also: previous post). We have also applied advanced techniques to obtain a detailed recording of the stela: RTI and laser scanning. This is exciting because it is the first time that a LBA Iberian stela has been recorded with these techniques!

If you click on the image (a default RTI image without enhancement) you will see the image that results from the application of the specular enhancement filter. As you will see it reveals many new relevant details.

The results of this research are currently being processed for publication. You can find more information in a previous blog-post

RTI & a prehistoric pottery sherd from Mirasiviene

While fieldwalking the country-estate of Mirasiviene, where the eponymous Late Bronze Stela was found (see: RTI shedding new light on Iberian Late Bronze Age stelae and RTI & the Late Bronze Age stela of Mirasiviene), we located an exceptional settlement. This is one of the many pottery sherds found on its surface. This sherd is […]

While fieldwalking the country-estate of Mirasiviene, where the eponymous Late Bronze Stela was found (see: RTI shedding new light on Iberian Late Bronze Age stelae and RTI & the Late Bronze Age stela of Mirasiviene), we located an exceptional settlement. This is one of the many pottery sherds found on its surface. This sherd is a piece of hand-thrown pottery with a thick wall, probably once part of a large scale container.

If you click on the image you will be able to visualize the RTI image with specular enhancement, which provides detailed information of its surface, with traces, among others, of its manufacture.


The data gathered during our fieldwork in Mirasiviene, which has been conducted by David Wheatley (University of Southampton), Leonardo García Sanjuán (University of Seville) and myself, is currently being prepared for publication.

RTI & the decorated stela of Montoro

This decorated stela was found some years ago nearby the town of Montoro, in the Middle Guadalquivir Valley (Córdoba, South Spain). In September, David Wheatley (University of Southampton), Leonardo García Sanjuán (University of Seville) and I have conducted fieldwork to inspect the place where it was found and we have also applied enhanced techniques to […]

This decorated stela was found some years ago nearby the town of Montoro, in the Middle Guadalquivir Valley (Córdoba, South Spain). In September, David Wheatley (University of Southampton), Leonardo García Sanjuán (University of Seville) and I have conducted fieldwork to inspect the place where it was found and we have also applied enhanced techniques to record the stela, that is, RTI and laser scanning. As you can see when you click on the image, the specular enhancement provided by RTI offers wonderful results. The stela is currently being studied and we expect to have the results ready for publication soon.

RTI & a prehistoric quern from Kellah Burn

This intriguing stone has been found by Joshua Pollard (University of Southampton) and his team during fieldwork on a site called Kellah Burn, in Northumberland, UK. The stone seems to have been initially used as a quern. Afterwards, the quern was decorated with this beautiful wavy motif. David Wheatley and I have applied RTI to see if the technique revealed more details of the surface of the stone than the ones seen by direct visual inspection, and also to facilitate its interactive visualization. If you click on the image you will see how the RTI specular enhancement reveals various interesting details that are not visible in the normal photograph.


The oldest erotic image in Estonia?

As one of the Estonian newspaper stated, it could be the oldest erotic image found in Estonia. It is an engraving on the wall of the old church in Lüllemäe. To get a better “reading” of the image we used RTI technique to document it. Here are some example screenshots below, interactive image can be […]

As one of the Estonian newspaper stated, it could be the oldest erotic image found in Estonia. It is an engraving on the wall of the old church in Lüllemäe. To get a better “reading” of the image we used RTI technique to document it. Here are some example screenshots below, interactive image can be viewed from Archaeovision’s website.


Karula

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