Cultural Heritage Imaging


Illumination of Material Culture: A Symposium on Computational Photography and Reflectance Transformation Imaging (RTI) at The Met, March 7-8, 2017 by chicaseyc

Our guest blogger, Emily B. Frank, is currently pursuing a Joint MS in Conservation of Historic and Artistic Works and MA in History of Art at New York University, Institute of Fine Arts. Thank you, Emily!

With the National Endowment for the Humanities (NEH) back on the chopping block in the most recent federal budget proposal, I feel particularly privileged to have taken part in the NEH-funded symposium, Illumination of Material Culture, earlier this month.

Co-hosted by The Metropolitan Museum of Art and Cultural Heritage Imaging (CHI), the symposium brought together conservators, curators, archaeologists, imaging specialists, cultural heritage and museum photographers, and the gamut of engineers to discuss and debate uses, innovations, and limitations of computational imaging tools. This interdisciplinary audience fostered an environment for collaboration and progress, and a few themes emerged.

The sold-out crowd at the symposium at The Met

The sold-out crowd at the symposium at The Met

(1) The emphasis among practitioners seems to have shifted from isolated techniques to integrating a range of data types.

E. Keats Webb, Digital Imaging Specialist at the Smithsonian’s Museum Conservation Institute, presented “Practical Applications for Integrating Spectral and 3D Imaging,” the focus of which was capturing and processing broadband 3D data. Holly Rushmeier, Professor of Computer Science at Yale University, gave a talk entitled “Analyzing and Sharing Heterogeneous Data for Cultural Heritage Sites and Objects,” which focused on CHER-Ob, an open source platform developed at Yale to enhance the analysis, integration, and sharing of textual, 2D, 3D, and scientific data. CHI’s Mark Mudge presented a technique for the integrated capture of RTI and photogrammetric data. The theme of integration propagated through the panelists’ presentations and the lightning talks, including but not limited to presentations by Kathryn Piquette, Senior Research Consultant and Imaging Specialist at University College London, on the integration of broadband multispectral and RTI data; Nathan Matsuda, PhD Candidate and National Science Foundation Graduate Fellow at Northwestern University, on work at NU-ACCESS with photometric stereo and photogrammetry; as well as a lightning talk by Chantal Stein, in collaboration with Sebastian Heath, Professor of Digital Humanities at the Institute for the Study of the Ancient World; and myself, about the integration of photogrammetry, RTI, and multiband data into a single, interactive file in Blender, a free, open source 3D graphics and animation software.

(2) There is an emerging emphasis on big data and the possibilities of machine learning.

Paul Messier, art conservator and head of the Lens Media Lab at the Institute for the Preservation of Cultural Heritage, Yale University

Paul Messier, art conservator and head of the Lens Media Lab at the Institute for the Preservation of Cultural Heritage, Yale University

The notion of machine learning and the possibilities it might unlock were addressed in multiple presentations, perhaps most notably in the “RTI: Beyond Relighting,” a panel discussion moderated by Paul Messier, Head of the Lens Media Lab, Institute for the Preservation of Cultural Heritage (IPCH), Yale University. Dale Kronkright presented work in progress at the Georgia O’Keeffe Museum in collaboration with NU-ACCESS that utilizes algorithms to track change to the surfaces of paintings, focusing on the dimensional change of metal soaps. Paul Messier briefly described the work being done at Yale to explore the possibilities for machine learning to work iteratively with connoisseurs to push data-driven research forward.

Mark Mudge, President of Cultural Heritage Imaging, leads a panel discussion

Mark Mudge, President of CHI, participates in a panel discussion

(3) The development of open tools for sharing and presenting computational data via the web and social media is catching up.

Graeme Earl, Director of Enterprise and Impact (Humanities) and Professor of Digital Humanities at the University of Southampton, UK, gave a keynote entitled “Open Scholarship, RTI-style: Museological and Archaeological Potential of Open Tools, Training, and Data,” which kicked off the discussion about open tools and where the future is heading. Szymon Rusinkiewicz, Professor of Computer Science at Princeton University, presented “Modeling the Past for Scholars and the Public,” a case study of a cross-listed Archaeology-Computer Science course given at Princeton in which students generated teaching tools and web content that provided curatorial narrative for visitors to the museum. CHI’s Carla Schroer presented new tools for collecting and managing metadata for computational photography. Roberto Scopigno, Research Director of the Visual Computing Lab, Consiglio Nazionale delle Richerche (CNR), Istituto di Scienza e Tecnologie dell’Informazione (ISTI), Pisa, Italy, delivered the keynote on the second day of the symposium about 3DHOP, a new web presentation and collaboration tools for computational data.

We had the privilege of hearing from Tom Malzbender, without whose work at HP Labs in the early 2000s this symposium would never have happened.

The keynotes at the symposium were streamed through The Met’s Facebook page. The other talks were recorded and will be available in three to four weeks. Enjoy!

Tom Malzbender, the inventor of RTI, at the podium

Tom Malzbender, the inventor of RTI, at the podium

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Reflections on Threats to World History by chicaseyc

Our guest blogger, Matt Hinson, is a junior at the School of Foreign Service at Georgetown University in Washington, D.C. He spent the summer as an intern at CHI. Thanks, Matt!

ISIS destruction at Nimrud

Screen shot from ISIS video of the destruction of Nimrud, April 2015

During my summer internship at Cultural Heritage Imaging (CHI), I learned a great deal about the danger facing many of the world’s treasures as well as the efforts to save them. My background in international history leads me to believe that international law and policy can help to address many of the dangers. I have also learned how CHI is contributing to the revolution in how we interact with information and deal with these cultural heritage threats.

The variety of projects that CHI undertakes demonstrates the wide range of threats facing cultural heritage. Although some of CHI’s most recent projects have dealt with weathering and natural deterioration, it is important to understand the other risks to humanity’s greatest treasures. One can categorize tangible cultural heritage sites into natural formations, historic structures, including cities and sculptures, and inscriptions. Complex rock formations, the cities built by ancient cultures, works of art, and monuments are all included. It is also important to recognize cultural heritage sites that hold symbolic value to a specific community or group. Many of these are protected by national parks and museums, but only to a certain extent. Multiple forces continue to threaten this material.

Threats can be divided into man-made and natural. The man-made category encompasses destruction from conflict, construction, and development. Human neglect can also be included as a potential danger to the survival of important sites. War has become one of the most widely observed man-made threats to cultural heritage, particularly in ongoing conflicts in Africa and the Middle East. Groups fighting for ideological reasons, such as religious fundamentalists, have attempted to destroy artifacts that contradict their beliefs. The recent destruction of the ancient city of Nimrud by the Islamic State is one prominent example. Conflict areas tend to encourage looting of historic sites, leading to sales of antiquities on the black market. Often the lure of financial gain from the development of sites that contain important heritage outweighs the cultural value that is at risk. One example is the impending destruction of an ancient Turkish cave city after the completion of a dam that will put it under water.

In most parts of the world, environmental threats to cultural heritage are more prevalent than man-made ones. For monuments, statues, and other structures made of stone, weathering is a common means of loss. Precipitation, especially acid rain, and other kinds of exposure to water can lead to the gradual erosion of stone, rotting of wood, and general deterioration of sites and monuments.

map-of-threats-from-sea-rise

National Park Service (NPS) map of the 105 US parks vulnerable to sea level rise. From “Strategies for Coastal Park Adaptation to Climate Change”: http://marineprotectedareas.noaa.gov/pdf/helpful-resources/webinar_beavers_schupp_nps_coastalcasestudies_111413.pdf

Environmental damage caused by climate change is accelerating the destruction. Rising sea levels are predicted to have a particularly devastating impact on many cultural sites. A recent study shows that predicted sea level rise over the next years will put 80% of Icelandic cultural sites at risk. According to the National Park Service (NPS), natural heritage sites in the US are also at risk. The NPS reports 105 parks as “vulnerable to sea level rise.” The effect on weather patterns due to climate change, particularly the increase in severe weather events, could pose major threats to cultural heritage sites beyond normal historical weathering.

How can these various threats be addressed? Archaeological preservation is one common method of physically excavating and preserving important historical artifacts. Moving objects to museums has successfully preserved different forms of cultural heritage throughout time. Digital imaging, practiced here at CHI, is a powerful tool to be used alongside archaeological methods to provide additional, more detailed information for the historical record. Digital representations of cultural heritage sites can be used to monitor the rates of change at these sites as well as preserve their shape and cultural significance. The re-creation of cultural heritage with digital methods also impacts how information is shared: an artifact that may be thousands of miles away can be viewed by anyone anywhere in an accurate digital form. This also allows objects and sites to stay in their original locations while providing access to their digital representations.

From my perspective, a crucial element in furthering the protection of cultural heritage is the legal and political protection of these sites. International law has developed to protect the things that have been identified as most sacred to communities around the world, including human dignity, life, and freedoms. Cultural heritage must be worthy of the same kind of protection every day as well as in wartime. Although some institutions already exist to defend cultural heritage, UNESCO, for example, I believe we must govern the protection of artifacts and sites with laws just as we do in cases of war crimes and sovereignty.

Another lesson I take away from my time at CHI concerns the changes in our interactions with information and knowledge. I am familiar with the usual media in our repositories of knowledge: text, photographs, video, and audio. While these media convey interpretations and descriptions of their subject matter, they rarely can stand as accurate representations of sites and objects. The potential that three-dimensional imaging brings to human interaction with information can be enormous. Many historical and cultural wonders previously limited to a particular geographical area could be made accessible to others, leading to progress in historical and interpretive research. Expanding research on these 3D methods, such as the ongoing work at CHI, can lead to highly effective ways of contributing to this revolution in information.

RTI study of the Sennedjem Lintel

The Sennedjem Lintel from the Phoebe A. Hearst Museum of Anthropology at the University of California, Berkeley. Lower left left shows the surface color and shape. Upper right shows an enhanced surface shape.

CHI has exposed me to a lot of these problems facing world heritage sites but has also introduced me to the preservation and information successes that are possible with different methods and technologies.



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/



Interview: James Coddington, Chief Conservator, Museum of Modern Art, New York by cwillen

CHI Executive Director Debra Dooley recently conducted an email interview with James (Jim) Coddington (JC), Chief Conservator at the Museum of Modern Art (MoMA) in New York. CHI is building a custom light array for MoMA’a Conservation Department to help with capturing reflectance transformation imaging (RTI) media of objects in the museum’s collection.

1. How long have you been at the MoMA?

JC: 23 years

2. As Chief Conservator at MoMA, are you constantly searching for new techniques to preserve and restore art?

JC: It is a necessity when conserving contemporary art in particular.

3. What are you doing to digitally document, analyze, and preserve the MoMA collection at present?

JC: We are using standard RGB imaging as well as multi-spectral imaging via a spectral estimation technique using a standard RGB camera with filters. We also maintain written digital documentation of treatments and other reporting.

4. Why have you decided to expand from what you are doing now into reflectance transformation imaging (RTI) techniques?

JC: The importance of 3D information in documenting works of art has been long recognized, mostly in the form of raking light photos. RTI gives us the means to collect substantially more 3D information in a standardized way that also provides data for scientific analysis of surface structure and topography.

4. Why did RTI interest you?

JC: I think mostly the demonstrated ease of use.

5. How will you use RTI?

JC: We will be using it initially to document texture on printed out photo papers but we expect to use it on many different types of objects in our collection.

6. A custom light array is being built for the MoMA. What objects will you capture first?

JC: See Answer #5.



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