Oregon State University researchers are helping preserve the legacy of Silver Falls State Park by using three-dimensional scanning to produce digital replicas of the park’s historical structures.
The work is especially timely given the increasing frequency of wildfires in Oregon and throughout the West, with fires destroying similar historical structures at Jawbone Flats in the Opal Creek Wilderness and at Breitenbush Hot Springs in Oregon in 2020.
Why Have Digital Records?
“Having a digital record of these buildings is essential, as that may be the only record we have,” said Todd Kesterson, senior instructor in OSU’s New Media Communications program and project director for the 3D scanning work. “If something is damaged or lost, that record can be used for repair or restoration.”
He pointed to the example of Notre Dame in Paris, which suffered significant loss in a fire in 2019. An art historian had conducted 3D scanning of the building in 2015, providing a perfect blueprint for the iconic cathedral to be rebuilt to an accuracy of within 5 millimeters.
For the Silver Falls project, Kesterson teamed up with Michael Olsen and Ezra Che in OSU’s College of Engineering. The project was paid for with a $14,163 grant from the Oregon Heritage State Historic Preservation Office.
The 3D Scanning Technology
The work involves two types of technology: photogrammetry and laser scanning. Photogrammetry uses a camera to take successive images of a structure, and then uses structure-from-motion software to stitch those photos together to build a three-dimensional digital replica. Laser scanning uses lidar (light detection and ranging) technology to record millions of points per second, measuring and mapping the exact shape and location of a structure at a high resolution.
The team selected three of the most well-known structures at the park: the South Falls Lodge, the South Falls Nature Store and the Stone Kitchen Shelter. They were built in the 1930s by the Civilian Conservation Corps as part of the New Deal, and most park visitors walk past them en route to the falls.
Olsen, Che and a group of graduate students set up laser scanners on tripods at various sites around and inside each building, capturing three-dimensional panoramas from different angles as the scanner rotated 360 degrees. They also sent a large drone 300 feet into the sky to take aerial photos.
Olsen said the bulk of his work focuses on monitoring infrastructure and natural environments for stability and erosion, but he has also done a lot of historical preservation work, even scanning the Renaissance-era Palazzo Medici in Italy to map the building’s deterioration.
Building the Digital Models
The researchers spent a day last month at Silver Falls gathering 3D scans. They will spend the next year processing the data and stitching the scans together to build digital models. Once complete, the photogrammetry models will be uploaded to a public database.
The precise digital models built from the laser scanning data will be given to the Oregon Parks and Recreation Department for them to keep and use for future restoration or rebuilding, whether due to a fire or other natural disaster, or the typical wear-and-tear that historical buildings experience.
Park ranger Matt Palmquist was among those evacuated from Silver Falls during the 2020 Beachie Creek Fire, and said park management was told there was only enough time and manpower to protect one structure. They chose the South Falls Lodge, putting sprinklers on the roof and moving all the historically significant objects outside the park. But it was “heart-wrenching” to think of the building going up in smoke, he said.
“We get over a million visitors here at Silver Falls, and probably 90 to 95% of them walk right through this district and right past these buildings,” Palmquist said. “It’s a really excellent spot to showcase the history here and the work of the Civilian Conservation Corps here at Silver Falls.”
Kesterson hopes that the Silver Falls work will highlight the importance of increasing 3D scanning of historical structures in Oregon and throughout the U.S., even though structures like the South Falls Lodge don’t receive national or international attention.
“I do hope this kind of project leads to greater awareness and has people really understand that this is an important part of our history, and we need to protect it on a digital level, as well,” he said.
