by Guest Blogger Eleni Kotoula, PhD student, University of Southampton, Archaeological Computing Research group
Application of normal and microscopic RTI to artifacts derived from the Hellenistic-classical Derveni cemetery in Macedonia, Greece, demonstrates RTI’s contribution towards prevention, investigation, documentation and communication. Microscopic RTI meets the conservation needs for limited human-object interaction, high quality and affordable visual analysis, advanced documentation and level of detail. Consequently, it does not only signal interesting developments of the technique, but also leads to its broader application in the cultural heritage sector and particularly in conservation practice.
Kotoula, E. And Earl, G. 2012. RTI and Conservation Practice, “Imaging in Conservation: Looking at artefacts under new light”: ICON meeting, Archaeology and Science Group, 10th – 11th November 2011, in STFC Rutherford Appleton Laboratory, Harwell Campus, Oxfordshire OX11 0QX. in press.
Filed under: News
We recently unveiled a brand new website at CultualHeritageImaging.org. It has been in the works for a while (these projects always take longer than you want them to…) There is a lot more information about our current work, and we hope you will find that the new menus and navigation make it easier to find things you are looking for. There are a few things I would like to highlight.
First, check out the totally new technologies section starting with the technologies overview
Then you might want to go to the downloads page to find guides and software for RTI:
We have an updated publications area, including information about two new books that are being published this year with CHI contributions:
And for a bit of eye candy, you might want to look at our library of videos on our Vimeo page:
These are also integrated throughout the site.
No such announcement would be complete without a few acknowledgments, and this one is no exception. Most of all I would like to thank Casey Cameron who volunteered an enormous amount of time to get all the content (old and new) into the new site. I don’t think that does her work justice as she wrote material, reorganized, and generally made all the content come together. I would also like to thank Mike Quillman for his design work including coding up the templates, making a maintainable system, coding the stylesheets, and so much more. Others that provided help, advice, and content include Marlin Lum, Tim Lindholm, Mark Mudge, Jack Dynis, Jon Cooper, and me (Carla Schroer) Lots of folks also helped review pages and content, and we really appreciate that.
I’d like to close with a request for help. Since the website has moved to a new location, it would be extremely valuable if you would help us spread the word by updating any links you have, blogging about us, “liking” our facebook page, and any other ways you can think of to help the new site be found by others. The old site (c-h-i.org) is still up for the moment, but we will be redirecting pages from there to the new site shortly.
Now that the new site is up, we hope to be a little more regular with our posts to this blog as well. (hey it’s a new year, I can hope can’t I?)
In July we were back at the Worcester Art Museum Conservation lab to give a training in our IMLS sponsored 21st Century Museum Professionals program. The Worcester conservation team was the first conservation lab to see the potential for Reflectance Transformation Imaging for art conservation back in 2006. We built a lighting array for them, and delivered it and a training in May of 2008.
It was great to be back with that team and to see a bit of what they have been up to. We were really impressed with their RTI work on Greek Vases. They gave us permission to post a paper about this work so others in the RTI community can see it.
See below for more information on the publication:
An Evaluation of Decorative Techniques on a Red-Figure Attic Vase from the Worcester Art Museum using Reflectance Transformation Imaging (RTI) and Confocal Microscopy with a Special Focus on the “Relief Line”
Authors: Paula Artal-Isbrand(1), Philip Klausmeyer(2), Winifred Murray(3); 1,2,3 Worcester Art Museum, 55 Salisbury Street, Worcester, MA 01609, U.S.A.
ABSTRACT
Decorative features on a Greek red-figure stamnos in the collection of the Worcester Art Museum were examined using Reflectance Transformation Imaging (RTI) and scanning laser confocal microscopy. These two surface examination tools helped to answer questions relating to the decorative process, particularly the tools and techniques that Attic painters used to create the so-called glossy black “relief lines” and “relief dots.” This research also incorporated fabricated mock-ups to help understand the ancient technology. It was determined that the relief line was not produced by an extruded method, but with a brush made of one or very few hairs, an idea first proposed by Gérard Seiterle in 1976 and termed Linierhaar. It was observed that not one but two distinct types of relief lines exist: the “laid” line (proposed by Seiterle) characterized by a ridge running through the middle of the line and the “pulled” line (proposed in this paper) which has a furrowed profile. Both line types were reproduced with a Linierhaar. Additionally, relief dots were replicated using a conventional brush. Surface examinations of other red-figure vessels using RTI and the confocal microscope suggest these conclusions apply to vessels of this genre as a whole.
Download the Publication: An Evaluation of Decorative Techniques on a Red-Figure Attic Vase from the Worcester Art Museum using Reflectance Transformation Imaging (RTI) and Confocal Microscopy with a Special Focus on the “Relief Line”
Thanks again to the team at Worcester for their wonderful hospitality and collaborative spirit! Keep up the great work.
Filed under: Commentary
RTI Photography of the Red-Figure Pelike
As the RTI user community grows and becomes more viral, more discoveries are made. Once in a while, a blog comes across my desk that is worth sharing. This is one of them. Click on the jump to get there.
http://deyoung.famsf.org/blog/rti-photography-red-figure-pelike
Thank you to Sue Grinols at FAMSF.
PS- nice blend map by the way (pretty good coverage for being set back on a table top!)
June 8, 2011
Buzzed at AIC
At the recent annual meeting of the American Institute for Conservation (AIC) in Philadelphia, I was happy to see both past and future participants in the IMLS-sponsored CHI RTI training session program. I had to break the news to some interested parties that the sessions at the Worcester Art Museum and at the San Francisco Museum of Modern Art are already filled (with waiting lists) – but a few openings remain (apply here) in the sessions scheduled for the Smithsonian’s Museum Conservation Institute and the Indianapolis Museum of Art. Since AIC, several spots have already been taken.
Of course, conservators always want more visual information, and have been quick to understand the benefits of RTI for their work. Once conservators attend a CHI training session, RTI adoption spreads throughout the conservation community. At AIC, I heard several tales of conservators reaching out to their curatorial colleagues, presenting the extremely detailed technical art historical information to be gained from RTI. Curators were impressed! The ability to acquire this kind of detail is one of the hallmarks of RTI – in fact, in CHI’s Kress video Debbie Evans (paper conservator, Fine Arts Museums of San Francisco) mentions that RTI can allow the conservator to provide this important, detailed information to the curator. We look forward to more wonderful conservator/curator interactions!
By Elizabeth Peña
Just before the memorial day weekend Mark and I had the pleasure of attending the Society for the Preservation of Natural History Collections(SPNHC) conference. A national conference (and a few international folks too) held here in San Francisco this year. We gave an oral presentation and a demo camp presentation. Both were well received and afforded us the opportunity to speak to folks from various institutions. We have done a lot of work with fine arts institutions, but only a few proof of concept projects with natural history collections. It was a real treat to have a chance to go to some talks and panel discussions and also a collections tour at CalAcademy. I have always thought natural history museums were interesting and important and cool, but this conference really brought home to me just how important these collections really are as a scientific record of our planet. Collections large and small are critical to helping us answer questions about the natural world both now and in the future. A great example I saw on the collections tour were finches collected in 1905 – 1906 from the Galapagos, where the preserved skins allowed current researchers to do DNA analysis to answer new questions. Since DNA analysis didn’t exist when the specimens were collected, this clearly wasn’t something they were trying to enable. And yet, if we do a good job at collecting and preserving things (objects, data, specimens, etc.) then they just get richer and more valuable over time. That is one of our goals at CHI, to make data increase in value over time by collecting high quality imaging data and good records of how it was collected and what was done to it.
It was a great experience to be at SPNHC, and we hope to attend next year when it is hosted by the Peabody Museum at Yale.
By Guest Bloggers:
Golya Mirderikvand (Art Conservation, Queen’s University) and George Bevan (Classics, Queen’s University)
In the fall of 2010 a Master of Art Conservation Student, Paintings Stream, at Queen’s University, Golya Mirderikvand was confronted with a unique challenge: how to document a reverse glass painting before beginning treatment. From the recto the painting is convex with the paint being applied on the concave verso. Because the flaking and delamination of the paint was on the concave side, it was difficult to produce raking-light shots that would fully reveal the variation in texture without creating internal shadows that obscured the surface. Reflectance Transformation Imaging (RTI), which had already been extensively used by George Bevan in Classics, was then employed as the ideal way to document such a work.
Figure 1: House next to Stream, Recto
First some background on the type of work in question. Reverse glass paintings, or more commonly known by their German name Hinterglasmalerei, refer to the decoration of glass by painting or engraving metallic foil on the back of a glass panel. Reverse glass paintings have a rich history with distinct variations in styles and techniques apparent from different periods. Although their exact origins in Europe are uncertain, it is generally agreed upon that they were popularized in the 14th century, with the oldest surviving reverse glass paintings dating from the second half of the 13th century.
Figure 2: House next to Stream, Verso. Imaged under normal illumination
Paintings executed on glass panels are inherently fragile and susceptible to deterioration since they are not fired to allow the paint to become fused with the glass. The primary mechanism of deterioration of reverse glass paintings is the detachment of paint films to the non-porous glass substrate. It has been speculated that a lack of proper preparation of the glass support in order to provide a better tooth, or a lack of application of a priming layer, or a combination of both, can lead to the delamination of the paint layers. Other possible reasons of detachment could be as a result of condensation of moisture on the surface of glass, causing the paint films to release. Internal and external factors contributing to the creation of interlayer shear forces can also lead to paint delamination. This can commonly occur as a result of any backings or adhesives in direct contact with the paint layer from the back, or changes in relative humidity causing contraction and expansion within the paint layers.
Figure 3: House next to Stream, Verso. Imaged using RTI.
Figure 4: House next to Stream, Verso. Detail of upper left area, with normal illumination. Delamination and Blind Cleavages are identified within red ellipses.
Figure 5: House next to Stream, Verso. Detail of upper left area with RTI. Delamination and Blind Cleavages are identified within red ellipses
Well, I love NY too.
In late March 2011, Mark Mudge, Carla Schroer, and Marlin Lum traveled to take a bite of the Big Apple and at its core was a 4-day RTI Training Session at the NYU Institute of Fine Arts Conservation Center. There, brilliant students and museum professionals participated in a 4-day hands-on RTI training. Each student learned how to capture, process, and view a Reflectance Transformation Image.
If you don’t know what a “RTI” is, read this, and you’ll have a better idea why it’s important:
“Reflectance Transformation Imaging (RTI) is a technology that has the potential to revolutionize documentation, treatment, and research of museum collections, while also promoting the integration of interactive images into the visitor experience. RTI enables museum professionals to examine an object’s very fine surface details using basic digital camera equipment and a few small additional tools.”
yup, we're capturing UV/IR RTis!
This training at NYU was partially sponsored by the Institute of Museum and Library Services. With the assistance of their funding, we are delivering 21st-century computational imaging tools into the hands of professionals who can make a substantial difference.
Brilliant Students(.)
As human beings on this earth for such a short time, we are striving to actually ‘make difference’ in people’s lives and in their careers. We want to make their work more meaningful and concrete. The final product is not just an interactive lighting map, but much more: knowledge, insight, value, and scholarly information, revealed by the artwork itself.
While on location at NYU, one of our students made an important comment. He pointed to the corner of the photo studio and said, “… that space there, that’s where, just last year, the photo enlargers were — we recently had them permanently removed.” (insert … silence, then echo laughter in a marble hallway)
NYU students during an RTI capture
That said, we’re moving right along into 21st-century computational imaging tools … we can now know more about our artwork than ever before.
A special thank you to NYU and *Hannelore Roemich.
Thanks for reading.
Marlin Lum
Imaging Director
Cultural Heritage Imaging.
PS: If you want to learn how to capture, process, and view RTI lighting maps, apply to the free IMLS-sponsored training sessions. Click here to get the details.
Discoveries made at every viewing!
“21st-Century Museum Professionals Grant Program”
Institute of Museum and Library Services
National Leadership Grant Project
Thanks to a generous grant from the Institute of Museum and Library Services 21st Century Museum Professionals program, CHI is pleased to present a series of FREE training sessions in Reflectance Transformation Imaging (RTI), graciously hosted by the following institutions:
Worcester Art Museum: July 11-14, 2011
San Francisco Museum of Art: Aug 15-18, 2011
Smithsonian Museum Conservation Institute: Mar 5-8, 2012
Indianapolis Museum of Art: Sept 10-13, 2012
Learn More. Space is Limited. Apply NOW.
http://www.c-h-i.org/21st_MP_apply/index.html
Metropolitan Museum of Art
In mid-December, we braved the cold and headed to the Big Apple for a 4-day RTI Training session at the Metropolitan Museum of Art, to be followed by a day of consulting on special projects. We were all delighted to be there and to enjoy the magic of Christmas-time in New York! And of course, it was a true privilege to be welcomed by the Met. Thanks to Larry Becker of the Objects Conservation Department for inviting us, and thanks to Carolyn Riccardelli and Ashira Loike for making all the arrangements and plans.
Larry Becker and the OCD (includes CHI)
Day 01
We began our Monday with introductory RTI lectures and our favorite fish fossil demo for an audience of nearly 50 museum employees! After lunch, a core group of 16 Met staff joined us for a hands-on RTI shoot. It was interesting to hear about each participant’s interest in RTI – examining armature marks on a bronze sculpture, looking at scratches on copper plates, searching for fugitive paint on a wooden object, and other great research questions. For the afternoon RTI shoot, an Islamic writing box was selected. The goal was to establish a condition image, with close-ups to examine construction details and to try to determine if the white inlay displays characteristics of bone or ivory.
Day 02
The following morning, we processed the writing box data set, creating an RTI. An interesting observation: we need an RTI databank, so that we know what ivory and bone are “supposed” to look like in an RTI image. In the afternoon, we headed to the objects conservation department and divided into two RTI capture groups and one processing group. Despite some technical glitches with the Met’s Nikon camera and new computer, a number of successful RTIs were created, from an enameled plaque to an engraved lead ingot. By the end of the day, the conservators seemed encouraged that they could really do this — and, Anna Serotta and Ashira managed to get the Nikon and computer up and running.
Day 03
One of Wednesday’s highlights was a lecture by CHI partner Dr. Szymon Rusinkiewicz of Princeton University. The audience seemed particularly interested in Szymon’s description of using computational photography to help mend a severely fragmented fresco. Szymon also discussed some of his ongoing collaborative work with CHI, including the research and development of algorithmic rendering using RTI capture data.
Most of the rest of Wednesday was a three-ring circus (in a good way) – three RTI capture stations were established, and conservators busily shot image after image. The intention was to provide practice with large and/or upright objects. Everyone seemed to be focused and engaged in the process. It was empowering to see Met staff taking over after only a few days of instruction. RTI = Reflection Transformation Imaging = Real Teamwork Involved!
Day 04
Thursday’s morning lecture covered post-processing issues, using highlight maps to show the actual light positions that were captured. The class considered different and better ways to gain even higher quality results. Then, RTI capture and processing moved back to the Objects Conservation Department. A bronze Bodhisattva, an African mask, and a historic violin were imaged – the conservators are still pondering the results.
Processing and viewing RTI files are easy, but it takes a good amount of concentration. Carla in teaching mode.
The class ended with a “show & tell”, and we got to see each other’s results! Our immediate feedback is that the conservators really took to the new technology and that they enjoyed working together as a team. From CHI’s perspective, we were gratified, pleased, happy, and exhausted!
Day 05 – Day of Consulting
The CHI team did return to the Met on Friday for a day of special consulting. Mark Mudge and Marlin Lum worked with Anna, Carolyn, and Ashira to document a relief in the Tomb of Perneb. Mark helped Debbie Schorsch and Daniel Hansdorf with a microscopy set up to shoot an RTI of a metal fragment – they were delighted to see toolmaker’s punch marks! Meanwhile, Carla Schroer used her software expertise to concentrate on RTI post-processing and viewing support.
After an eventful and productive week at the Met, the CHI team returned to California feeling like we’d not only worked with new colleagues, but made new friends.
By Elizabeth Peña and Marlin Lum
