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Mapping the past

THE BALTIMORE SUN

Michael Raphael believes the best defense for our national monuments is a good offense. With so many statues and buildings vulnerable to potential terrorist attack in a post-Sept. 11 world, he said, it makes sense to get the most accurate measurements possible of all that can be surveyed -- just in case.

The problem is that the plans and photos that document many monuments don't contain enough detail for an identical restoration.

So in December, a small partnership -- Spatial Integrated Systems Inc. of Rockville, and Raphael's Direct Dimensions of Owings Mills and Washington architect Scott Knox -- created an ultra-accurate three-dimensional computer model of the Lincoln Memorial on the Mall in Washington, using laser scans to record the tiniest of details.

In case of calamity at the Memorial, the National Park Service could have what they need to re-create the massive, marble statue of a sitting President Abraham Lincoln and the columns that stand before him.

The three companies hope their demonstration will show how technology can help restoration efforts for national and international treasures.

Several people with interest in preserving national monuments and institutions, including representatives from the Smithsonian Institution, the National Park Service and Historic American Buildings Survey, attended the six-hour measuring session in December.

"I'm intrigued by this as a facilities architect because it is a way to record what we have ... that is much more accurate than hand-collected data that we have had to rely on in the past," said Mary Kfoury, lead architect for the Smithsonian, who watched the measuring work. "If we were to use it to the maximum degree, it would allow us to record every kind of bump and wrinkle on a building."

Missing parts of a structure could be restored more accurately if curators can work from a model of other sections of a building, Kfoury said. And, with three-dimensional measurement and modeling, caretakers of unique historic treasures would be able to accurately repair or re-create monuments and buildings damaged by everything from fire to terrorist attack.

The demonstration at the Lincoln Memorial was coordinated by Scott Knox, who recently set up a nonprofit organization called the Institute for Monumental Architecture. The institute has a proposal for assisting in potential restoration efforts of the Parthenon in Greece, and is seeking funding for the technological effort.

The Olympics' return to Athens in 2004 has sparked renewed interest in the Parthenon, which for many outsiders is the most visible symbol of ancient Greek culture. The structure, famous for its columns and pleasing proportions, was built 2,400 years ago atop the Acropolis as a temple to Athena, the city's patron goddess.

Over the centuries, the Parthenon has been shattered by an explosion and portions of the structure have been stolen. As with the much newer Lincoln Memorial, completed in 1922, blueprints, drawings and diagrams can't do the original work justice.

Raphael, whose engineering firm takes complex measurements of objects large and small, says that when the three partners began asking for permission to scan the Lincoln Memorial in the summer, he learned something.

"You don't just show up at a national monument with all of this equipment," he said. "Then Sept. 11 occurred, and they all but called us to come."

While each project has its quirks, the Lincoln Memorial scanning ran much like the scans of other large structures -- although a few practical matters had to be dealt with first.

For example, the scanner couldn't just roll across the marble floor, said Chris Korkalo, a sales engineer at SIS, who operated the laser scanners that day with his wife Christina, a scanning expert who also works for the company. So they put down a floor covering.

Chris Korkalo said the project used "time of flight lasers," which fire beams that bounce back from the object being measured. The devices capture the position of thousands of points per second, creating measurements down to the millimeter.

Once the measurements were in the computer, Direct Dimensions interpreted the data with sophisticated modeling software. The computer model included the Lincoln statue, the columns and the detailed work that appears above them. The scan itself had some limitations, though: SIS didn't have time to take the equipment behind the statue, so details of the back of Lincoln's head are missing from the computer model.

With a picture of the object described mathematically inside a computer -- Direct Dimension's offices are dotted with high-end Pentium workstations -- the computer rendering was turned into a highly accurate resin model, using a rapid prototype machine.

Such machines create non-working models by spraying tiny amounts of paper or resin into layers that slowly form the shapes described by the computer file. Direct Dimensions, which has worked closely with the Army on Aberdeen Proving Grounds projects, used the Army's machines to produce the models.

The partners were still waiting this week to receive the last part of the 20-inch-by-8-inch-by-11-inch resin Lincoln model.

Knox took the Lincoln statue portion of the resin model to Greece last week to show off the partners' work to others interested in the Parthenon's restoration.

Laser-scanning and measurement have been used for large industrial projects for some time, and SIS has used the technology on projects for the Navy.

In 2000, SIS measured an abandoned New York subway tunnel that was left unfinished in the 1960s to aid current efforts to connect the tunnel to the rest of the system. Korkalo said two 1.5-mile-long tubes were scanned over 13 days for work on a new line from Manhattan to Queens.

Direct Dimensions has performed 3-D scanning and measurement of objects -- from massive sculptures to human ears to Israeli navy boat propellers.

The company also has taken on a role in the race to re-create Wilbur and Orville Wright's historic flight at Kitty Hawk, N.C., for a centennial celebration next year. Working with the Wright Experience restoration effort based in Warrenton, Va., Direct Dimensions has made models of propellers and smaller engine parts to help replicate the plane.

The company also has worked on the mystery of how the Wrights, who were relatively secretive in their efforts, developed the airplane propeller between 1903 and 1911. By 1911, Raphael said, the Wrights had all but perfected it.

"Even NASA has not been able to figure out how they did that," he said.

So Direct Dimensions staffers have traveled to a number of locations where propellers made by the Wrights are stored -- the Wright State Museum in Dayton, Ohio, and the Franklin Institute in Philadelphia among them -- to scan and model the parts. By matching accurate measurements with the Wrights' notes, engineers hope to piece together the process by which the brothers came up with such a good propeller design.

Measuring buildings that date back hundreds of years may prove just as helpful. For example, the Castle, the Smithsonian's signature building built in the 1850s, has only rudimentary documentation.

"You have to bear in mind the dates for these buildings," said Kfoury, the Smithsonian architect. "A lot of these buildings date from a period when architects didn't need to create detailed drawings. Fine detail work may have been conveyed from the designer to the craftsman in the field."

While later installation of equipment and renovations may have left plans and other forms of documentation for the buildings, 3-D scanning and modeling would provide far more information.

It would be useful to museum curators, too, said Kfoury. Artifacts such as dinosaur bones and finely detailed jewelry could be modeled with accuracy for archiving.

The work doesn't all have to be grim documentation in the face of disaster or purely educational either, Raphael said: "Think of video games in which we put real objects in virtual worlds."

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