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Fairfax, Va., Uncovers History With Multispectral Imaging

With the help of multispectral imaging technology, the city of Fairfax, Va., has uncovered hidden meaning in the graffiti left behind in a historical site by Union soldiers during the Civil War.

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Multispectral imaging at Historic Blenheim in Fairfax, Va.
Photo courtesy of R.B. Toth Associates
The city of Fairfax, Va., embarked on a project last year using multispectral imaging technology to analyze Civil War-era graffiti in a local historic site.

Technological tools have proved useful in reviving historical spaces and multispectral imaging, specifically, has been very successful in the detection of hard-to-discern details such as environmental threats.

The project, titled New Insights into Interior Surfaces of Historic Structures with Advanced Imaging Research, was funded by the National Park Service and used the imaging technology to conserve the writings and information recorded on the walls of Historic Blenheim, a farmhouse that housed Union soldiers during the Civil War.

The city bought the farmhouse in 1999, knowing there were inscriptions within, according to Andrea Loewenwarter, historic resources specialist for the city’s Office of Historic Resources. The intent of the project was to discover more information about the property and those who stayed in it using a noninvasive method.

The project was led by the city’s Office of Historic Resources. R.B. Toth Associates was brought in as a partner to conduct the imaging. George Mason University was also a collaborator, helping the city determine the best platform for data storage.

After a free demonstration by R.B. Toth Associates in June 2020, the city applied to a grant from the National Center for Preservation Technology and Training within the National Park Service, according to Loewenwarter. The grant, for nearly $20,000, was awarded to the city of Fairfax in August 2020.


According to Michael B. Toth, R.B. Toth Associates’ president and chief technology officer, the project had two main technological components: capturing images of the walls and managing the resulting data storage.

“Multispectral really builds on what we all see when we see a rainbow,” explained Toth. “So, we take advantage of the capability now with modern LEDs to be able to create illumination in narrow bands of light.”

There are two ways to achieve these narrow bands of light, he said. One is to filter the white light, limiting the amount of energy received from an object. The other is to only put the energy into the desired wavelengths. That includes visible wavelengths like the reds, greens and blues as well as those that humans cannot see: ultraviolet and infrared.

Light panels with LEDs generate light in these various illuminations, and a photo is captured with each of these using a 100-megapixel camera.

The photos reveal things that the human eye cannot discern on its own. However, as Toth explained, the image that is most clear may differ from one person to another. Individuals who are colorblind, for example, may prefer the grayscale image because they see the images through a different perspective.

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Comparison of different illuminations in multispectral imaging project at Historic Blenheim in Fairfax, Va.
Photo courtesy of R.B. Toth Associates


The project resulted in a half terabyte of data, Loewenwarter explained, adding that public access to the information gathered was a key goal of the undertaking.

The photos are now hosted through a platform called Omeka, developed by George Mason University’s Roy Rosenzweig Center for History and New Media.

Omeka, Toth explained, is an open source tool for cultural heritage applications that helps to make the data more easily available. He added that GMU’s involvement helped not only in preserving the data but also in making it publicly accessible.


Toth detailed that while the use of technology like this in cultural heritage is under-resourced, by building on how it is used in other spaces, like forensics, program and data management protocols can be brought to historical projects like this one.

Although the technology is well established for some uses, Toth explained that typically it is used to photograph a single object. Using the technology on vertical walls required him to move the lights and camera rather than simply moving the object.

Additionally, each wall posed its own challenges, as Loewenwarter described. For example, a stairwell restricted where the camera could be placed for a couple of walls. Water damage and earthquake damage had weathered walls differently.

As a result, each wall required a different approach. The inclusion of a color standard enabled comparisons between walls.


One discovery revealed through this process, Loewenwarter said, was a signature belonging to “Stephen W.” However, the last name was unclear until she used a database to determine that it belonged to Stephen W. Millichamp with the 1st Michigan Cavalry. With that information, she was able to dig further and find a photograph of him from a living relative.

“That really brings the soldiers to life,” she said. “It was an incredible process, from not knowing who that person was to being able to discover and have that three dimensionality — and to be able to tell his story, his service and his life.”

She also noted that the site is in a group of graffiti houses in the Northern Virginia Civil War Graffiti Trail, and GMU recently applied for a grant to study other houses in the area with graffiti, so more projects of this type may occur in the region in the future.
Julia Edinger is a staff writer for Government Technology. She has a bachelor's degree in English from the University of Toledo and has since worked in publishing and media. She's currently located in Southern California.