Cultural Heritage Imaging

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

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.

Capturing Reflectance Transformation Images by cdschroer
September 30, 2009, 1:52 am
Filed under: Technology, Training | Tags: , ,

By Debra Dooley, Executive Director, and Marlin Lum, Imaging Director, CHI

We have quite a bit of information on Reflectance Transformation Imaging (RTI) on our website. But what’s the process used to create a RTI? There will be several blog entries on the process. For more detailed information we recommend that you sign up for the Digital Imaging Techniques for Conservation & Education 3-hour workshop. Check out a Flickr photostream of one of the workshops.

There are four different parts to the process: Preparation, Capture, Processing, and Viewing. This blog entry is a high-level summary of the Capture process.

There are two different methods used to capture RTI. One is called Highlight RTI and the other uses a hardware system. CHI calls the custom hardware systems we build “RTI Capture Hardware Systems” and they are usually built for specific types of objects.

Highlight RTI

The highlight method is easy to use in the field as well as in a controlled setting. You use a tripod, digital camera, a light source (strobes or continuous lighting) and other generally available equipment. That’s one of the big pluses about highlight RTI —  “over the counter,” pro-sumer photographic equipment will yield professional, museum-quality,  high-grade digital RTI surrogates.

This picture was taken after one of the workshops. This is a classic “camera down” or “floor setup,” and is pretty basic. Basics include: a tripod with the camera mounted in the down position, a wireless trigger set (pocket wizards), a 580EXII flash strobe (with a string attached), and a priceless stone tool (insert your artwork here) in the field of view.

Carefully placed next to the object are two round black shiny reflective spheres. When the strobe hits the shiny surface, it produces a “highlight.” Bling! Bling! Software used in processing the images finds the highlights in each image to derive a light position (LP).

Also in this image is a Canon EOS Digital Rebel, tethered to a laptop and being controlled by the Canon EOS utility software. The blue tape minimizes movements and vibration during the capture process. The sandbag hanging from the ball head also dampens the wiggles. Again, though basic, the results are high tech.

Highlight RTI setup

Highlight RTI setup

RTI Capture Hardware System

The RTI Capture Hardware System is better suited to controlled settings such as in a museum conservation photo/lab. One benefit of using a rig is efficiency.  Think mass production, or in this case, mass-documentation. A RTI rig/dome is extremely favorable if one needs to document a large quantity of similar sized objects: coins, signatures, stone tools, paper samples, paintings, objects, etc. etc.

The most noticeable feature of an RTI Capture Hardware system is the light array — many lights (up to 40) mounted at different angles, all directed toward the center, at the object. And of course the camera is also mounted at the apex of the unit. A PC laptop controls the light sequence and asks the camera to open the shutter when a lamp is on, capturing the image with different light positions.

This capture sequence is  managed by open source software that we teach you how to use in our workshops, so you should look into it if this is interesting to you.

4-Day Training: Reflectance Transformation Imaging:
“Generating Digital Representations of Cultural Heritage Objects”

The following image is of a custom RTI Capture Hardware System built as part of the Developing Advanced Technologies for the Imaging of Cultural Heritage Objects project. CHI built 2 identical systems, one for the University of Southern California’s West Semitic Research Project and one for CHI.

Custom RTI Capture Hardware System

Processing the Images. After capture comes the processing of your images. Stay tuned for an update on that soon.

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.


Wanted: Heritage Heroes by cwillen

The United Nations Environment Programme (UNEP) declares World Environment Day each June, making this month a time to focus on how we can improve our environment and our planet.

Our global cultural heritage is a vital element of our environment. Like our natural and physical world, heritage sites and artifacts have been adversely affected by climate change and other negative environmental effects, many caused by human activities.

UNEP has created the Champions of the Earth Laureates Program to recognize the extraordinary efforts made by dedicated researchers and activists to increase environmental protection and awareness.

CHI has been inspired by the UNEP program to create a Heritage Heroes initiative that appreciates people in the heritage community who have advanced the field in so many ways. UNEP recognition categories include science and innovation, policy, inspiration and action, and entrepreneurial vision.

The CHI team can think of numerous cultural heritage workers who deserve recognition in each of these areas and in other categories, too.

However, for our first nominee, we have selected someone who has really led the way in promoting digital techniques to document and preserve cultural heritage.

Tom Malzbender, senior research scientist at Hewlett Packard Labs, has helped the field of digital cultural heritage by developing, refining, and sharing  advanced imaging techniques and other processes to digitally document and preserve artifacts.

Listen to him describe interactive relighting in a post on this blog. We hope you agree that he is a heritage hero! Let us know about your heritage heroes by posting comments in our blog.

We are interested in all kinds of heroes — not only those who excel in technology, but also those who inspire others to action — historic preservation advocates, fieldwork fiends, educators, and those working in other relevant fields.

Preserving Places & Objects That Matter by cwillen
June 2, 2009, 8:29 pm
Filed under: News | Tags: , ,

By Claudia Willen

Please join Cultural Heritage Imaging (CHI) in celebrating National Preservation Month this May. The National Trust for Historic Preservation selected “This Place Matters” as the theme for the 2009 preservation month. Visit the trust’s preservation month page for more stories and inspiration:

The CHI team has discovered many places that matter all over the US and the world. CHI wants to show everybody how to digitally preserve the places and objects that matter on our planet and share information about these treasured cultural resources so others will understand why they matter so much and why we need to save them.

Tell Us About the Places and Objects That Matter to You
In honor of National Preservation Month, let the CHI community know what cultural heritage means to you and what you think needs to be digitally documented, physically restored, heroically saved, or just better appreciated in general. We look forward to hearing from you via email or in the blogosphere!