In the central passage of George Washington’s mansion at Mount Vernon, a graceful black walnut staircase, built in 1758, has its guts fully exposed. On display are a wrought-iron rod, a steel I-beam, a steel channel and tie-rod, and two additional wood stringers—all added over the years to help stabilize the structure. This time, workers are tightening the existing framing joints. But before the underside can be closed and refinished with lath and lime plaster, the Mount Vernon Ladies’ Association (MVLA)—the nonprofit that has owned and maintained the Virginia estate since 1858—has an important project left. During my visit in January, Tom Reinhart, the site’s deputy director for architecture, told me that workers will laser-scan the staircase interior and add the data to a historic building information model and management system (HBIM).
Developed by Washington, D.C.–based Quinn Evans Architects (QEA), Mount Vernon’s HBIM is among the first of its kind. It provides a framework to integrate historical and cultural information about the site with a 3D representation of the buildings and landscape. “Software is hardly ever developed for historic preservation, so we have to be innovative in how we incorporate available tools,” says Alyson Steele, AIA, a Quinn Evans principal.
Over the centuries at Mount Vernon, a mish-mash of additions, repairs, and surveys has left a mountain of documentation. Are the floorboards in the New Room original? Did the doors always swell in the springtime? Is the deflection of a truss’s upper chord increasing? No longer will conservators have to go hunting through scattered archives. Now that information will be linked to the relevant parametric objects in the 3D model—the HBIM’s most groundbreaking feature, says Esther White, Mount Vernon’s director of historic preservation and research.
What’s happening at Mount Vernon reflects the expanding use of digital tools in historic preservation. This technology is helping to streamline historic site management, to enhance the visitor experience, and to aid in landmark restoration. It can also help preservationists expand their roles. “Preservationists do crazy, wonderful, extravagant things to save the termite-eaten piece of wood that George Washington may have looked at,” says Andy Ferrell, chief of the architecture and engineering program at the National Center for Preservation Technology and Training (NCPTT), an office of the National Park Service (NPS). “But I also see preservation broadening beyond the artifact itself, as we think about larger issues like sustainability and resilience.”
For example, preservationists can use geographic information system (GIS) modeling tools to chart how historic sites relate to their present-day environments and communities. This, Ferrell says, could help preservationists be more involved in managing how sites evolve over time.
Documentation of historic sites is on the rise in part because of advances in three-dimensional laser scanning and digital photogrammetry. Take the digital documentation of the Lincoln Memorial, in Washington, D.C., expected to be completed this spring. The project is being undertaken pro bono by DJS Associates, a Pennsylvania-based forensic firm, on behalf of the NPS and CyArk, an Oakland, Calif.–based nonprofit that is building an online library of heritage sites.
In December 2013, a team of four technicians, each equipped with a laser scanner and camera, spent two days documenting the monument. Jon W. Adams, director of architectural and heritage services at DJS, says that each scan encompassed a 360-degree panorama, measuring millions of surface points per second to an accuracy of a few millimeters. Onboard computers stored the scan data into 3D point clouds, which were then blended into one large cloud, from which plans, sections, and perspectives can be extracted. The data will give the public a more detailed snapshot of the memorial, and will allow the NPS to monitor weathering or settling. “Our mission is to create a highly accurate record that could be used to help restore or reconstruct the monument,” says Elizabeth Lee, vice president of CyArk. “We not only get 3D images, we also get engineering-grade data.”
One site in particular has become a laboratory for emerging technology: Flushing Meadows–Corona Park in Queens, N.Y., the site of two Worlds Fairs, in 1939–40 and 1964–65. Although few original fair structures remain, the landscape is dotted with several ruins, including the Philip Johnson–designed New York State Pavilion, a monument to Space Age futurism.
Jennifer Minner, an assistant professor of planning at Cornell University, is researching using 4D GIS at the site—a combination of 3D GIS and procedural modeling that adds the dimension of time. A proposed “time slider” will toggle between historical and existing conditions, as well as future scenario models. Funded by an NCPTT grant, Minner’s team is exploring the capabilities of CityEngine, a 3D GIS program, and how it can work together with architectural modeling programs (such as Maya and SketchUp) to give the public more input into what happens at the site.
In 2009, Lori Walters, a research associate in the history department at the University of Central Florida, received a grant to re-create the 1964–65 World’s Fair virtually as an educational resource—and wound up inventing the children’s computer game ChronoLeap. Based on archival photographs, official drawings, video footage, and interviews with fairgoers, Walters and her colleagues modeled the vanished pavilions in Maya. They also laser-scanned the surviving landmarks to create the game’s environment, and players can explore how modern-day gadgets may have evolved from experimental technology exhibited at the fair.
But why stop at making a game? “Once the models are built, the data can be repurposed for any number of uses,” Walters says. Indeed, she has shared her 3D pavilion models with researchers at the Rensselaer Polytechnic Institute, who are developing an augmented reality app for smartphones and tablets. The app will give visitors access to reconstructed views and audiovisual recordings from the 1964–65 fair, geolocated to the user’s location. “Faced with an expanse of empty space, users will instead find themselves surrounded by the buildings that were there, and they can learn what’s inside,” says Tamar Gordon, who co-created the app with Rebecca Rouse.
The app’s augmented reality is different from the full immersion of virtual reality—and that’s a good thing, Rouse says. “It doesn’t subsume your field of view, so there’s a critical distance and layering that happens.”
Rouse is also working with the Rensselaer County Historical Society in Troy, N.Y., to design a mobile, interactive, augmented reality app for exploring the local Hart-Cluett House. Called Below Stairs, the app allows visitors to discover the house through the eyes of a new servant auditioning for employment on the occasion of a winter ball held in 1850. “You get a series of tasks from the cook, which take you through the house itself and introduce you to the lives of those who lived and worked in the house,” Rouse says.
At Mount Vernon, conservators are also bringing new depth to the site’s interpretation. They’re emphasizing the functional relationships among the two dozen or so structures and the landscape, the complex history of slavery and liberty, and the ways economics and the environment helped shape the architecture.
In these realms, the HBIM promises to make a significant contribution. In a pilot phase last year, QEA used Autodesk Revit to create a 3D database of the mansion, with a sample room modeled in rigorous detail. The HBIM shares the 3D building model from Revit via a plug-in with Esri ArcGIS, the program used to build a GIS model of the site. The biggest challenge was to create an intuitive interface to navigate the model. The architects opted for Esri CityEngine, which translates from ArcGIS. The result is a user-friendly, interactive 3D “webscene” accessible on a desktop or mobile browser.
Robert Fink, AIA, the QEA associate who led the system’s technical development, took me on a test drive. As he virtually peeled back walls and ceilings, he clicked on various building components. Tabs appeared indicating the current condition, systems and utilities, as well as information about the Washington period, preservation, and interpretation. Users can also search by component, date, material, or craftsperson. Each piece of information is rated with estimated levels of reliability and accuracy, so it’s easy to locate knowledge gaps.
QEA is expanding the HBIM to include the rest of Washington’s mansion by this summer, and will eventually add all 20 or so of the site’s outbuildings. To incorporate over 250 years’ worth of archives into the geospatial database could take decades, Mount Vernon’s Reinhart predicts. Indeed, says Fink, “The project will never be finished.” The database will be constantly updated with ongoing research and preservation work.
In 2016, a public version of the HBIM will be published online. It will offer a dynamic view of Mount Vernon, one that defies the image of an artifact unchanged since the American Revolution. And it will help us grapple with the messy contingencies of the site’s cultural significance—helping us to envision how this landmark figures into our past, as well as our future.