AiA in 3D: 3D Laser Scanning (and Printing!) at SERC and Wye House

We’ve been dealing with some very cool technology lately, both in the field and back on campus.  Ben Skolnik, Stefan Woehlke and I presented a paper at the Society of Historical Archaeology Annual Conference in Seattle talking about the costs and benefits one of AiA’s most recent and exciting tools — a 3D laser scanner.  During the summer of 2014, we were able to use it to scan our work in the field — in other words, the scanner spins, using millions of lasers to scan the landscape while also taking photographs.  Import this data into the computer software and what you have is an interactive re-creation of the landscape, unit, or feature in digital 3D.  With this type of data, Ben was even able to isolate one of the girts of a ruined frame structure at SERC and use a 3D printer to create a small-scale model.  Below you’ll find an adapted version of our paper, as well as a photos and videos of the process!!  After all, this is all about the visuals.

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The FARO 3D-Scanner at SERC, 2014 AiA Field School (photo by B. Skolnik)

An Intro to 3D Laser Scanning in Archaeology

In recent years, companies such as FARO and CyArk have begun incorporating 3D laser scanners into field-ready packages.  Archaeologists have successfully employed these new 3D laser-scanning techniques to record sites such as Mount Rushmore and Merv in modern-day Turkmenistan.  Despite the potential benefits of using this technology, which produces quickly scanned, high-resolution images of topography and features, several limitations have slowed it from entering the archaeologist’s standard toolkit.  It exceeds the budget of many archaeological research projects and the large quantities of digital data recorded by these machines (often millions of points) present challenges in both manipulation and curation of these datasets.  Additionally, methodologies that incorporate these scanners as a part of excavation remain undeveloped.  This paper explores the use of a 3D laser scanner by Archaeology in Annapolis at several sites, and offers an evaluation of its successes and shortcomings as a tool to aid archaeological excavation and research.

Archaeologists have frequently turned to new and innovative technologies to assist in the excavation, recordation, and interpretation of sites.  Radio-carbon dating is perhaps the most profound example of a technology that has fundamentally changed the discipline; but there are many other tools and methodologies that have been developed that assist us in digging up the past.  As the cost of terrestrial LiDAR systems comes down, we expect that it will be used more and more frequently as a part of the archaeological toolkit.

Terrestrial LiDAR, also referred to as 3D laser scanning, uses active pulses of laser energy to create a detailed three-dimensional digital model of a mapped surface.  The instrument sends out a pulse of light in the [range of the spectrum] at a known angle.  That light energy travels along that specific trajectory until it encounters some physical object in its path.  Upon hitting this object, some of the energy is reflected back to the instrument platform.  The scanner records the time it took for the laser to make this round trip as well as the intensity of the energy returning.  Because we all known the speed of light (…299,792,458 meters per second, in case you need a reminder!) , we can take the time it took for the signal to return to the sensor, divide it by 2 (because it had to go there AND back), and divide by our speed to get the distance between our sensor and the point we just mapped. We can now change the angle at which our laser leaves the scanner and map another point.  If we repeat this process millions of times, we end up with a digital model of the surface we just mapped.  If you’ve ever spent time in the field, you’ll know how long it takes to map by hand, or even using a total station and prism — this process not only does all of this in a fraction of the time, but records everything, including exact distances.

Using the 3D Scanner at Wye House and SERC

Wye House

Excavations at Wye House in Talbot County demonstrate the value of using 3D scanning to record contexts in situ as they are excavated.  This deposit was located beneath what was once the entrance to a brick slave quarter on Wye Plantation.  The context, which consisted of a number of circular objects laid carefully beneath the entrance – including colored, white, aqua, or metallic artifacts that mediate the watery barrier between the living and the dead in African spirit practices.  This type of deposit must be carefully mapped and recorded prior to and during each stage of its removal – and this is where 3D scanning is a particularly valuable resource.  Using the scanner, millions of points were collected that allow for the deposit to be reconstructing digitally, preserving exact locations and measurable information that would normally take hours or days to record by hand.  Another benefit to using the 3D laser scanner at this site is the opportunity for community engagement with archaeology.  To put it bluntly, it’s a cool technology.  At Wye House, members of descendent community came out and watched as Ben gave a demonstration of the scanner, and were fascinating by how ‘high-tech’ our terrestrial excavations had become.  It regards to generating public interest and creating a visual product that can communicate the archaeology to a wide audience –point clouds are not only aesthetically interesting but interactive – 3D laser scanning holds a lot of potential.

SERC

During the 2014 field school at the Smithsonian Environmental Research Center, Archaeology in Annapolis conducted testing around the extant remains of a late 19th century frame building, likely a tenant house for the Sellman Family Farm in Edgewater, Maryland (previously a slave-holding plantation).  Now a part of the SERC campus, the wooden frame of this structure forms a visible ruin on the landscape – albeit a delicate one, as the wood has been subjected to decades of the elements.  Many of the components of the structure, including beams, girts, a fallen chimney, and brick piers, lay relatively undisturbed where they have fallen, and present the opportunity to imagine a reconstruction of the building through their careful recordation.  Our archaeology focused of the exterior of the structure so as not to disturb the fragile ruin, with test units in the front, back, and side yards, but the 3D-laser afforded us the opportunity to record what was left of the tenant house in a level of detail that drawings, maps, and photographs wouldn’t have captured alone.  With millions of points taken and stitched together, the structure can be rotated, zoomed in on, and explored in full 3D on a computer.  Further, one of our team [Ben, I’ll give you credit for this] was able to isolate one of the architectural elements from the structure – the long girt along the east [right?] side – and import it into MeshLab, allowing us to use 3D printing technology to recreate a small scale replica of the piece.  With further work, the potentials of this type of technology in archaeology present the means to recreate high-detail and 3-dimensional models of archaeological sites at every stage of excavation, both digitally and physically.

The Costs and Benefits

There are many benefits to having a tool like this available at an archaeological site like the two described above.  One is the ability to map things quickly and accurately, as we discussed in the intro section above.  This type of technology records sites and contexts so well that you would be able to go back and look at an entire context in situ, and interact with it digitally, even after it’s been removed.  (Never forget that excavation is a destructive practice — once something is taken from the ground, it cannot be put back, which makes recording one of the most important parts of our process!)  Another benefit is the potential for community engagement — exciting technology gets people interested, and is a great way to engage people of all ages at an archaeological site.  Beyond that, the images produces are both interactive and beautiful, and provide the potential for things like 3D printing.  These are the types of products that can be used in archaeological education, museum exhibits, community outreach and online resources.

There are some drawbacks to 3D scanning as well.  The main obstacle is price — it is a very expensive piece of equipment, and not all archaeology projects can afford it.  Even our scanner, which was the entry model from FARO, was an expense that we shared with our School of Architecture at the University of Maryland, College Park.  It is important to understand that in addition to the cost of the scanner itself, there are other associated costs to keep in mind.  Computers, data storage, software licenses and training must all be factored into the budget for a 3D scanner.  Another drawback is the size of the data, which requires high processing power and a lot of space for storage.  Working with these datasets can take a lot of time, depending on how fast your computer is (and some computers can’t handle it at all!).

As the cost of terrestrial LiDAR platforms comes down, it is almost certain that they will be used more and more frequently in archaeology.  This means that archaeologists will need to develop good methods for using them in the field.  As they enter our toolkits, we will need to think more about how best to use these scanners to the benefit of archaeology and the communities we work with!

 

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Full ‘point cloud’ at SERC (screenshot by B. Skolnik)

 

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What We’ve Been Up To!!

The Fall semester has been a busy one for AiA.  Over the summer, we completed two successful field schools — one at SERC and Wye House, and another at Montpelier and Easton, MD — but a lot has happened since then.  This blog post will bring you up to speed on some of the things that have kept us busy the last few months!

AiA goes to Ireland

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Why Ireland?

Six University of Maryland graduate students, including many from Archaeology in Annapolis, traveled to Ireland for less than a week—far too little time—as the culmination and continuation of a class we took together in January. The class was taught jointly by Dr. Mark Leone at the University of Maryland and Lee Jenkins at the University College Cork, Ireland, along with several guest lecturers whose expertise ranged everywhere from Irish prison archaeology to critical readings of Frederick Douglass’ autobiographies. What sort of class covers both Irish history and Frederick Douglass and unites students from Maryland and Cork? One that explores the transatlantic connections between the Irish and African diasporas. While navigating the challenges that come with holding lectures over Skype, our sometimes lagging and pixelated conversations brought together our diverse interests and perspectives.  – Beth Pruitt

About the trip!

As a follow up to a winter term course on Frederick Douglass and Transatlantic Connections, 8 archaeologists from the University of Maryland went to Ireland for a week long exploration of the archaeology and landscapes of Ireland. In addition to spending time in Dublin and Cork, we took a day trip to Belfast where we met with archaeologist Laura McAtackney. She showed us around the city, going to a museum of Irish Republican History, on a tour of City Hall, and, of course, a Black Taxi Tour of East and West Belfast, stoping to sign the peace wall. What struck me was the physical segregation of two groups of people on the landscape which was almost impossible to miss, but also their separation culturally, which was much more subtle and difficult to see and understand. This separation could have been missed by an outsider (like us), who could have easily mistaken all these people as “residents of Belfast” or “Irish people”. This closely resembles how outsiders (archaeologists) could accidentally lump separate groups of people together in the past. – Kate Deeley

Presenting the Archaeological Findings from the Talbot County Women’s Club

Archaeology is often a very long and arduous process of gathering, organizing, and evaluating the information that comes out of the ground.  But it’s worth it!  On September 9th, Tracy Jenkins gave a presentation to the Talbot County Women’s Club on the excavation the club hosted at its historic property in Easton, Maryland, in 2013.  We were drawn there to look at free African Americans of the nineteenth century.  In the final stages of analysis this summer that the presence of two outbuildings became fully apparent.  One was a kitchen used approximately 1795-1891 where African-American cook Harriet Anderson worked in the 1870s and ’80s.  We were excited to share with the Club what we had discovered about their property, though the identity of the second building and traces of metalworking evidence across the site are still a bit of a mystery. – Tracy Jenkins

Frederick Douglass Conference

Frederick Douglass has become one of the most important figures in Maryland history. He was born and raised on properties owned by the Lloyd family where Archaeology in Annapolis has excavated for a decade. There, he escaped from slavery, but was still a slave legally. He determined he would end slavery in North America. Not only did he reach that goal, but also on the way decided to commit to ending permanent disfranchisement for the people of Ireland by making a strong alliance when he was 27 years old with Daniel O’Connell, known as “the Liberator” of Ireland. In order to bring archaeological scholarship at Wye House on Frederick Douglass and slavery into a Trans-Atlantic context, my students and I met with Douglass scholars from the Department of English at University College Cork in September of this year. Three weeks later those scholars came to College Park and visited Wye House. The joint symposium focused as much on the ways subordination from the nineteenth century have been extended into the twenty-first century as it did on the life of Douglass and the details of his accomplishments. The scholarship showed that the issues of freedom from oppression in North America and in Ireland may not be exactly the same, but techniques for removing freedom and narrowing the terms of existence continue and require the same kind of keen surveillance that Douglass constantly sought.  – Dr. Mark Leone

And that’s just the start of it — we’ve got a lot more going on this semester (and next).  Here are a couple of things that you can expect to see on the blog over the next few months:

  • A magnetometry survey session at SERC
  • The wonders of the 3D laser scanner and how we’ve been able to use it at SERC, Wye House, and Montpelier
  • More on Reynolds Tavern in Annapolis and the artifacts found there during the 1980s excavations
  • More on the trip to Ireland (including photos, and maybe even the Irish students’ perspective!)
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Archaeology in Annapolis comes to SERC!

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The “Homestead House” was the home of the Sellman family for two centuries — our site is several hundred meters back, in the woods, and was likely a tenant house.
(Image Source: http://www.kathypoole.com/Converted%20Images/SERC/Excerpt%20from%20SERC%20Master%20Pland%20Report.pdf)

Archaeology in Annapolis this year has the great honor of working with the Smithsonian at the Smithsonian Environmental Research Center (SERC!).  This is a very exciting partnership — not only is the SERC campus home to some of the most cutting-edge environmental research in the world, but a great deal of history as well.  Also, SERC’s Citizen Science program provides opportunities to incorporate the public as volunteers in a variety of research — including archaeology.  This commitment to public engagement at SERC aligns with AiA’s own investment in public archaeology, a top priority of AiA since its beginnings over 30 years ago.  Jim Gibb’s work at Sellman’s Connection has been an outstanding example of Citizen Science in action — excavating  alongside volunteers to test the area around the 18th century house that first greets you when you drive down the winding road (at a leisurely and strictly upheld 15 MPH) and enter SERC’s campus.  We were lucky enough to get the grand tour from Jim in the spring, and thus came to choose our site for this year’s field school.  And so, we arrived last Tuesday — the Archaeology in Annapolis 2014 Field School — armed with shovels, trowels, screens, and notebooks (among many other things we use out there).

This is just the beginning — and our students themselves will be sharing their experiences on our blog throughout the season.  So for now, let’s bring you up to speed on our site and some history at SERC.

Where We Will be Excavating:

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(Image Source: historicaerials.com)

During his mapping of Sellman’s Connection, Jim Gibb located what appears to be a late 19th century foundation in the wooded area, several hundred yards behind the Homestead House (Woodlawn).  At one point in time, a road had connected this structure to the larger house and the main road beyond it.  This can be seen in several historic topographies dating back as far as 1905, and as late as the mid-1990s.  What this structure was for has yet to be seen in any written records, but its location and size suggest it was a possible tenant house for laborers during the 19th and early 20th centuries.  It was mostly likely constructed using wooden planks, a building material much more ephemeral and less costly than the bricks used to construct the main house.  As we don’t know much about this structure or those who used it, archaeology will be an important tool to tell us about what this building was, what it was used for, and by whom.  Another important tool will be oral history, as many of the local community members remember a time when this building still stood and have specialized knowledge about the local history of the area.

Brief History of Sellman’s Connection

The Sellman family’s history in Maryland can be traced back to John Sellman, who arrived in America in 1658 as a twelve year old indentured servant, required to work in a single household for over a decade to earn his freedom.  Throughout his life, he worked his way from indentured servitude to owning his own plantation.  His son, William, later moved to the 360-acre plantation called Shaw’s Folly that now lies within SERC’s campus.  There, he and his wife Ann built the house that you see there today, known at SERC as the Homestead House but named Woodlawn when it was built in 1735.  This house was home to several generations of Sellmans, including General Jonathon Sellman who fought at Valley Forge with the Continental Army in 1777-78.  Several additions were added to this house over time – a wing in 1841 and another in 1979 – and it likely had several outbuildings and tenant houses for the hundreds of men and women who worked there as slaves and paid laborers through the 18th, 19th, and early 20th centuries.  According to Richard Donavin, a descendant of the Sellman family, many African American men and women remained after the Civil War as paid laborers, but little is known about their lives and the conditions they faced.[1]  Jim Gibb and many volunteers have uncovered some clues to this past, including a potential 19th century slave quarter and food preparation building in the field south of the Homestead House and a brick foundation, probably of a 19th century dwelling, in the yard west of the House.[2] 

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Map of Gibb Excavations, 2014
(Image Source: http://www.gibbarchaeology.net/discoveries/SERC/sellman.html)

The Sellman family sold the property to Yvone Kirkpatrick-Howat, an avid tree collector, in 1915.  According to local knowledge, at one time there had been a tenant house (AA-149 MHT) that had previously served as two slave quarters (later joined together).  While this is not the structure that we will be investigating, it speaks to the presence of slaves and tenants at the plantation, and could be a potentially similar building to the one we will be investigating.  This is drawn from 1987 report done by the Maryland Historic Trust, which cites Samuel Asker, a tenant farmer for Yvone Kirkpatrick-Howat at the time.[3]

Throughout the 19th century, much of the surrounding land was used by Robert Lee Forrest as the Java Dairy Farm – the land the eventually became the beginning of SERC’s campus.  The foundation that we will be excavating belonged to a building that stood throughout this time, from as early as the latter part of the 19th century well into the 20th century and the memories of many local community members.  The land containing the Sellman property was bought by the Smithsonian in 2007.[4]

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Reynolds Tavern: Adventures in Site Report Writing

Reynolds Tavern, 7 Church Circle, Annapolis.

Reynolds Tavern, 7 Church Circle, Annapolis. Source: http://www.flickr.com/people/auvet

In 1984, excavations ceased at the historic Reynolds Tavern in Annapolis.  Four years later, I was born.

You could say I solidly missed the opportunity to excavate this site, one of the first of many projects to be undertaken by Archaeology in Annapolis.  Reynolds Tavern, built by William Reynolds on Annapolis’ historic Church Circle, has served variably as a home, a tavern, a hat shop, an inn, a bank, a library, and a restaurant since its construction in 1747.  Records tell us that Reynolds made hats in his basement, ran a tavern upstairs (though intermittently), and sold slaves from his front porch.  The building has had a long history since its original owner, but Reynolds has remained its namesake; today the building operates as a restaurant of the same name, with a small inn upstairs and a popular pub in the basement.

Reynolds Tavern met its first archaeologists in Kenneth and Ronald Orr, who undertook the initial excavations in 1978.  Four years later, the project came to Archaeology in Annapolis, and three more seasons of archaeological work took place.  Notes were recorded, drawings drawn, pictures taken, artifacts cataloged.  Now thirty years later, these were my pathways to the site I would end up re-excavating, step by step, only this time armed with nothing more than post-it notes and a scanner.

When I was first invited to finish the site report for Reynolds Tavern, which had been picked up and picked at only a few times over the years, I was intrigued, but also a bit unsure of whether or not it was a task I would be able to accomplish, so far removed by time from the excavations themselves.  Not being able to associate notes with the actual experience of working on a site left me feeling blind, and more than a little lost.  However, not even a month later, what I found myself in the middle of was a mental excavation.  Peeling back layers of data, trying to associate one item with another of the same paper ‘strata’, making notes on exactly where I was finding what and trying to piece it together later.  The artifacts were just codes on a page, the units just sketches on paper, but slowly, I began to see what had happened thirty years ago.  Despite my initial trepidation (and some admittedly mind-scattering notes from the 80s), the Reynolds Tavern site report has come together, piece by piece, and proved to be both an adventure and a truly gratifying learning experience. (Though I’ll take the field any day, but wouldn’t we all?)

But this adventure in site-report-writing has not been without its exciting moments.  There’s much more to this story: there are the actual finds of the 1980s excavations (the well, the cobblestone road, the African bundles, among others), the exhibit-to-be in the basement of the present day Reynolds Tavern, the discovery of the artifacts (again!) in the secret, cavelike room beneath Woods Hall, and as of today, the hundreds of photographic slides pulled from archives to be digitized for the first time.  But these are other blog posts, for other weeks!  Until next time.

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