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New Research at CWB Could Save Museums Tens of Thousands of Dollars As they Preserve Large Objects….Such as a Boat

May 17, 2014

Federal Grant to CWB Developing New Photogrammetry techniques
that will be shared with all Museums

(Seattle,WA) With funding from a competitively won federal grant, The Center for Wooden Boats in Seattle has launched a research project that could dramatically reduce the cost of tracking the shapes of large objects in a museum collection as they change over time. Knowing when an artifact is changing shape is critical for a museum so it can step in and take steps to stop the damage. That is especially true with large objects because often by the time a change in shape is perceptible to the human eye irreparable damage has already been done.

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For CWB the large objects to be preserved are among the 150 the historic sailboats, row boats, steam and electric launches in its collection that document the classic small craft designs of the northwest. But there are 17,500 museums and 123,000 libraries in the U.S. that will have access to the new techniques developed by CWB that they can use to help document and preserve objects in their collections.

With the grant from the Institute of Museum and Library Services, CWB’s Fleet Manager Kyle Hunter has been working with a group of experts in vessel documentation to use digital photography and computer aided design software to develop more cost effective ways to document a boats shape. “Today techniques to capture a boat’s shape often require laser scanners that can cost a museum $100,000 or more,” said Hunter. “Using common photography and relatively simple software the cost of creating a digital model of a boat can be brought down to just a few hundred dollars if you have a decent camera and a quick computer.” The models that Hunter has created from the CWB collection are of a high enough level of accuracy that it could be submitted to the Library of Congress’s engineering database. Using laser based techniques could have cost many thousands of dollars to create the same model.

Photoscan takes dozens of photos of same object and maps individual points in relation to other points on the boat

Software can recognizes the details in the overlapping photographs. Once aligned, the program will build a dense point cloud. This point cloud has over 18 million points.

The research is still under way, but clearly the early results have been positive.

Hunter and the experts he’s brought together in Seattle have been able to use a digital camera to make detailed photo sets of boats shot from many angles. Computer software can take those photos and detect the lines and edges and quickly convert the photos into accurate 3D wire frame models on a computer. Once that computer model is documented, another photo scan of the boat can be done at any time and the two models compared. The computer can instantly show the curator how and where the boat shape has changed. That’s critical to know so a curator can decide if it’s time to jump in with additional steps to stop the change in the boat’s shape.

Heatmap showing Change from one Scan to the Next

Comparing two scans. Weight was added in bow of boat on second scan. Change in hull shape from added weight clearly visible in Red.

CWB’s small boat collection offers an ideal test of the technology as the museum has had a longtime program to document the shape of its historic boats, and that earlier data can be used now to test these new techniques. Working with partner maritime heritage organizations such as Northwest Seaport, and the historic records division of the National Park Service, CWB tests can be run comparing these new results to existing methods of gathering similar data.

The impact of this research could be significant, according to David Cockey, President of the Museum Small Craft Association. Cockey traveled to CWB in Seattle earlier this year to participate in a training session on the new technology. “Many museums with small boats have to deal with boats in storage and that fact that and there are some boats you can’t take into the collection”, said Cockey. “This new technology helps those museums capture the information in those boats and preserve it for the future.”

One appealing aspect of this new technique that has researchers excited is that, because it begins with taking digital photographs, it is easy to start quickly. Historians only need to learn the techniques of how to take the photo sets needed using a mid-priced digital camera. (CWB used a Canon G-1, which costs about $600). The data does not need to be processed immediately. As long has you have the archive of photographs it’s possible to do the processing at any time. And it is possible to use photographs taken many years ago to document boats that may no longer exist. The team from Northwest Seaport that is helping CWB in the research had taken detailed photographs in the past of the cabin on the historic schooner Wawona, which was dismantled in 2009. Using the new techniques developed through the CWB research the team has been able to use those old photos to create a detailed computer model of the Wawona cabin even though the boat is long gone.

That ability to jumpstart preservation of boats, before it’s too late, is what prompted Eric Hervol a former museum shipwright now with Western Washington University to come to the CWB training session earlier this year. “With these techniques, even if we can’t save all of these vessels we can capture what they are now….and capture the history before it literally rots away outside somewhere,” said Hervol.

But boats won’t be the only objects tested. To ensure the new techniques are usable across different museums with different kinds of collections, CWB is required to run test on something that doesn’t float. Hunter has chosen to use the technique to document the design and shape of the Tlingit Honor Pole at CWB. The pole was carved by high school students in the Alaskan village of Klawock and installed at CWB in 2005 as a way of saying thank for a 40-foot cedar canoe that was carved at CWB and gifted to the village.

Honor Pole in Lidar and Photoscan

Photoscan on Left, LIDAR scan on Right. Center heatmap comparison, where red shows variations, shows only minor differences despite much higher cost for LIDAR process

The scan of the Honor Pole at CWB was a success, and shows the technique can be used to produce accurate models of similar objects at a much lower cost, again in comparison to laser scanning. The success of that test has already caught the interest of experts working to preserve native monumental carving. Hunter will present preliminary findings of the research this July at the Tribal Conference on the Preservation and Conservation of Totem and Honor Poles. They are not the only group interested. Hunter has already presented on the technique being developed at CWB to the Northwest Archeology Conference annual meeting and the Council of American Maritime Museums national conference in April. He will also present in June to the Washington Museum Association’s annual meeting and the Society for Historical Archeology has invited Hunter to present at its next international conference in January of 2015.

The new techniques for photogrammetry being developed by CWB are designed to help in preservation, but Hunter is already thinking about other ways to use this technology. CWB has a fleet of 8 Blanchard Junior Knockabout sailboats built by the Blanchard Boat Company from 1933 to the mid-1950s. “Because these new techniques are so inexpensive and easy to do we would be able to scan the entire fleet, and compare boats build in 1930 with those built the 1950s and document how the boatwrights at Blanchard tweaked the design of the boat over the decades in response to customer demands and changes in technology”, said Hunter.

Compare different Blanchards to See how design changed over the years

Two Blanchard Jr. Knockabouts scanned by CWB will allow the team to compare changes in design from early boats in the 1930s to later construction in the 1950s.

CWB expects to wrap up this research project in by the end of the year with a final report to IMLS detailing the merits of this new camera based photogrammetry, its strengths and weaknesses, how it compares to the more expensive alternatives, and how to make it accessible to organizations.. It’s then the research will be ready to be shared even more broadly with other museums in the US and around the world.

Photographing Twilight

Team scanning a Northwest Seaport boat while it was still in the water….to see if they could get photo data set without taking a boat out of the water.

Scan of Twilight

Detailed photo data from scan of “Twilight” while she was still in the water.

 

 

 

 

 

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