Cultural Heritage Imaging


RTI Experimentation with a Copper Breastplate in the Florida State Bureau of Archaeological Research by marlinlum

This is a Guest Blog by Photographer Joseph Gamble.

As an affiliate with the University of South Florida’s Alliance for Integrated Spatial Technologies, I traveled with a team of archaeologists doing imaging research and 3D laser scanning of artifacts to Tallahassee last year to work in the Florida State Bureau of Archaeological Research (BAR) and experiment with RTI on a number of Native American artifacts from Lake Jackson, Florida. AIST Directors, Drs. Travis Doering and Lori Collins along with AIST archaeologist Dr. Jeff DuVernay, helped me to manage a challenging RTI of a Native American copper breastplate as well as other copper and metal objects from Lake Jackson and several other Florida sites.

Native American copper breastplate from Lake Jackson, Florida

The artifacts were from the ancient Lake Jackson settlement, a civic-ceremonial center of a Mississippian chiefdom that flourished across parts of northern Florida between c. 900-1500 A.D. The breastplate (23 X 54 cm) was cold-hammered from a sheet of native copper and contains extensive iconographic and symbolic that today are faint and difficult to discern. In the 1970s, the piece was encased in a clear Plexiglas, cube-like chamber that had been infused with argon gas as a conservation measure to halt corrosion of the artifact. The reflective polymer barrier that enclosed and protected breastplate seemed to pose an insurmountable obstacle for its accurate high resolution documentation. To stabilize the breastplate it had also been pressed into a plaster base to prevent further fragmentation and distortion leaving the piece with a cracked or crenelated surface texture. This condition was an additional for the documentation because of the shadowing that further limited the usability of the image set.

To acquire an inclusive data set that would contain sufficient usable images to build an RTI, we placed the case on black velvet, mounted the black balls and commenced to shoot. The total image count came to 156 raw files of which 57 were used to build the RTI file and, much to our delight, it worked well.

View the Final RTI File by clicking here (you tube video).

Joseph Gamble is a previous 4-Day RTI Training graduate. You can learn more about Joseph Gamble Photography at: http://www.jcgamble.com/

You can learn more about the Alliance For Integrated Spatial Technologies at: http://aist.usf.edu/

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Imaging Paper Squeezes With RTI at the Smithsonian by cwillen

By Guest Blogger E. Keats Webb

I mentioned briefly last month some of the objects that we have been using Reflectance Transformation Imaging (RTI) on here at the Smithsonian’s Museum Conservation Institute (MCI).  One project involved paper “squeezes,” paper pulp molds made from the surfaces of ancient monuments at archaeological sites.

In some cases these “squeezes” are primary resources containing rare intellectual and physical information from monuments that have deteriorated or sites that no longer exist.  Unfortunately, the fragility of the paper minimizes accessibility of these objects to researchers and scholars. This makes them great candidates for non-destructive documentation of the 3-D characteristics of their surfaces with the RTI method.

Senior Conservator, Melvin Wachowiak, and I worked with the conservators from a Smithsonian museum, imaging a couple of examples of paper squeezes to see what the RTI method might contribute in terms of preservation and research.

Since the squeezes are molds taken from stone inscriptions, the writing is reversed.  After the image acquisition we “flipped” the images using imaging software, and then processed the files so that the final RTI product could be a legible rectified document for researchers to study.

We found that the RTI method increases legibility through the combination of raking light features and the specular enhancement option while also creating a surrogate that can be more extensively “handled” by researchers and scholars. (See images below.)

We continue to use RTI on a daily basis and look forward to sharing more with you about how the method is helping the scientists and conservators within MCI and the Smithsonian for the research and preservation of the collections.

paper_normal_lite

Detail of Paper Squeeze with Normal Light Position

 

Paper with raking light

Detail of Paper Squeeze with Raking Light

 

Paper with specular enhancement

Detail of Paper Squeeze with Specular Enhancement



RTI @ the Museum Conservation Institute by cdschroer

By Guest Blogger  E. Keats Webb

Over the past three months I have been interning with Senior Conservator, Melvin Wachowiak, at the Smithsonian’s Museum Conservation Institute (MCI) exploring advanced imaging techniques for research and preservation of the collections focusing mostly on the Reflectance Transformation Imaging (RTI) method.  We started in September with an African leather shoulder bag, the RTI enhancing the faint tooling and degradation on the surface. In October we imaged a writing slate from the 1600s found in an archeological excavation of a well at the site of Jamestown, Virginia.  RTI proved an excellent tool in interpreting the drawings and writings that are found on both surfaces of the slate and at all orientations.  Other types of objects that we have explored include paper “squeezes” (molds taken from stone inscriptions), oil paintings, a jawbone, ebony and ivory inlaid cabinet doors and a daguerreotype.  We work alongside scientists and conservators on a daily basis at the Museum Conservation Institute, and RTI complements the studies happening within our labs along with other advanced imaging techniques used for research and preservation.

Set-up for the RTI of the Jamestown Slate.

E. Keats Webb left, Melvin Wachowiak right; Photo: Charles Durfor



On Location with an Anthropoid Coffin and the FAMSF RTI Capture Team by marlinlum
FAMSF_RTI_group_shot

Susan Grinols and her RTI capture team document an Anthropoid Coffin

In October 2009, Susan Grinols – Director of Photo Services and Imaging for Fine Arts Museums of San Francisco (FAMSF), assembled a team of scholars and imaging professionals to document an Anthropoid Coffin with the highlight RTI technique.

Sue and her team  members were thrilled with the final results. Using the RTI Viewer, suddenly, hard to decipher glyphs were clearer and easier to view. The curators, interpreters and conservators were shocked at how the RTI technology delivered so much detail, in a completely nondestructive manner.

For a brief look into the RTI capture session be sure to view the flickr gallery.



CHI’s National Park Service Workshop by cdschroer

By Carla Schroer

The National Park Service’s National Center For Preservation Technology and Training (NCPTT) workshop was a great opportunity for the instructors as well as the participants. First, Mark and I got to spend a couple of days with Tom Noble and Neffra Matthews (from the Bureau of Land Management) prior to the workshop.

Tom and Neffra are extremely knowledgeable photogrammetry experts with lots of field experience. They also keep up with what’s going on in that field in terms of new products, and new features in existing products. They are a tremendous resource, and happy to share their knowledge. CHI welcomes any future opportunities to work with them again.

The next opportunity for me as an instructor was to hear from folks that participated about their own experiences in the field. A few had tried reflectance transformation imaging (RTI), others photogrammetry, others laser scanning, and all had done photographs and drawings (or been part of projects that did that).

The workshop afforded opportunities to discuss practical issues in the field, as well as get an understanding of some of the challenges people face, and what they are willing to do to overcome the challenges. The group worked well together, shared ideas readily, and asked good questions. I think we all got a lot out of the interaction. It wasn’t just instructors passing knowledge to students, and I really appreciated that aspect of it.

It was also fantastic that we had a range of people with a wide variety of  experiences participating. Having Professor James Davis from the University of California, Santa Cruz attend the full workshop was really valuable, because he could hear directly the issues people face, and share his perspectives as a computer scientist.

James has worked with RTI for some years, and is also well versed in a range of computer graphics techniques, including laser scanning, structured light scanning, and other forms of capturing 3D geometry. He was really interested in the challenges in the field, and what takes the most time and is the most painful about the capture process, always thinking about ways he might be able to remove some of the time consuming parts.

Overall the experience was lively, interactive, open, and fun, but we made serious progress, too. I think it added a lot to have folks staying at the Presidio and getting to know each other in the evenings. Several people mentioned how the opportunity for them was in not only getting access to the technical information, but interacting with other participants.

I think that no matter how good we get at training people with web- based materials, there will always be a place for human interaction and sharing. It was a rich experience, and I truly thank everyone involved for participating fully.

NCPTT-Workshop-Grp-Photo



Visualizing the future at Arqueologica 2.0, Seville, Spain by Michael Ashley
June 23, 2009, 10:37 pm
Filed under: Conferences | Tags: ,

by Michael Ashley

arqueologica logo

I had the pleasure of being invited to a special congress in Seville this past week. Arqueologica 2.0 is the first international congress on archaeology and informatics held in Spain. The organizers managed to bring together over 200 participants from 17 countries representing over 100 organizations, to discuss and debate virtual archaeology and its role in archaeological practice. I found the congress to be inspirational, exceptionally well run, and mostly a whole lot of fun.

Participants included representatives from some of the most important organizations that work to document, understand, preserve and communicate cultural heritage around the world. In fact, the congress was a truly international gathering of professionals who are passionate about cultural history and memory.

So often, the discussions of computer graphics and archaeology focuses on the divide between technologists and practitioners of the discipline. I was impressed by the efforts of the congress program facilitators to get us to look beyond the fissure and to the mutual benefits of integrating visualization methods into archaeology.

Jane Crawford and Michael Ashley at the opening session at the site of Italica

Jane Crawford and Michael Ashley at the opening session at the site of Italica

Throughout the congress, many recommendations and suggestions have been forwarded. I mention a few here because they resonate well and I hope we would generally agree are essential to promote the broad adoption of digital technologies in service of archaeology.
Bernie Frischer suggested that future Arqueologica meetings might have workshops to leave behind practical training with participants.
Richard Beacham called for case studies or pilot projects where we can test ideas and refine procedures in the real world.
Graeme Earl and several others suggested that virtual archaeology methodologies are actually archaeological techniques that must be truly integrated and carried out in archaeological practice.

Throughout the congress, many recommendations and suggestions were forwarded. I mention a few here because they resonate well and I hope we would generally agree are essential to promote the broad adoption of digital technologies in service of archaeology.

Bernie Frischer suggested that future Arqueologica meetings might have workshops to leave behind practical training with participants.

Richard Beacham, co-author of the London Charter on visualization in cultural heritage, called for case studies or pilot projects where we can test ideas and refine procedures in the real world.

Graeme Earl and several others suggested that virtual archaeology methodologies are actually archaeological techniques that must be truly integrated and carried out in archaeological practice.

Mediterranea Project

Mediterranea Project

Many of us were kindly invited to listen to Alfredo Grande discuss the ambitious Mediterranea Project, which seeks to integrate the cultural heritage of the Mediterranean for research and public access and enjoyment. Core to the project is an attention to ‘big blocks’ that are essential to archaeological work practice – documentation and research, conservation and preservation, presentation and information.

One of the highlights of the scientific program was the uniquely organized quick fire plenary session that involved 23 of us lined up in the first row of the auditorium. From the stage, Víctor Manuel López-Menchero Bendicho gave us each <2min. to summarize our opinion on the state of virtual archaeology. This led to a lively debate with many more questions than answers, but there was general consensus that even now in 2009, we are only scratching the surface at the potential for digital archaeology.

Daniel Plentinckx in the spotlight during the rapid fire plenary

Daniel Plentinckx in the spotlight during the rapid fire plenary

Arqueologica 2.0 was the first of what the sponsor organization, the Society for Spanish Virtual Archaeology (SEAV) (also launched at the congress), hope will become an annual event. I hope so, not because the world needs another conference, but because the spirit and enthusiasm expressed by our new friends in Spain is what the world needs.

My favorite quote from the congress was made by a colleague, “It’s more important who you work with than what you work on.” I would work with Alfredo and Victor anytime. I am sure we can find some really important things to do in an enjoyable fashion.

Muchas gracias por todo, nuevos amigos!