“The archaeologists mapped everything,” Biddle said. “The mapping techniques they used worked, but they couldn’t capture the important small de- tails needed for engineering and planning.” He and his colleague, GIS Specialist Joel Cusick, knew that 3D laser scanning combined with on- site imagery could provide the needed precision. But while NPS had previously used scanning, it had never tackled such a large site with dozens of complex, sometimes crumbling structures. Capturing the Kennecott data As part of ongoing work at Kennecott, NPS is planning to stabilize the upper seven stories of the mill, which remains one of the largest wood- en structures in North America. The effort will require replacing deteriorated structural beams and columns, many of which are out of plumb or lack structural integrity. Engineering and con- struction teams need accurate data on these and other components. To gather additional information, NPS worked with Trimble and Anchorage-based Frontier Precision, Inc. Neil Robicheau, a surveyor and geospatial specialist with Frontier, explained that the team developed a plan to blend multiple geo- spatial solutions to produce comprehensive data and imagery of Kennecott’s mill. The team al- located a full week for fieldwork and processing. In addition to creating an accurate 3D dataset, Cusick needed to connect the data to existing survey control and property boundaries. Working directly on the existing survey grid would make it easy to bring the scanning data and images into a GIS or other earth-based reference frame. “There are a number of private inholdings re- maining around the mine,” he said. “We needed to be sure we weren’t scanning someone else’s property.” Upon arriving at Kennecott, the surveyors used GNSS to set control points tied to existing geo- detic control markers on the site. They then used a Trimble SX10 scanning total station and Trimble TX8 scanner for the bulk of the work. In addi- tion to handling the 3D scanning, the SX10 could tie to existing control points and use traverse or resection functions to establish georeferenced positions on each setup point. The SX10 collected scanning measurements and
A georeferenced Trimble VISION photo mosaic of the Kennecott mill from the valley floor. Blue lines show GNSS measurements, green are from SX10 traverse and direct reflex data.
View of scan data, survey points and detail photograph of an electrical connection in Trimble Business Center. The data enables inspection and measurement of inaccessible locations.
images from more than 20 locations around the mill. From setup points on steep hillsides the SX10 could capture top-down views and data on inaccessible features. Technicians used the instrument’s panoramic and telephoto cameras to collect “big picture” photos as well as high-resolution images of critical details. The instrument also captured 3D points and images of overhead tram cables running into the mill as well as complex, often inaccessible structural components. In addition to scanning and photography, the teams used direct reflex (DR) measurements to capture individual points on the building. These points could identify key features and then be compared with the point cloud and photos for quality assurance. In one instance, they used DR measurements to a window more than 330 feet above the instrument. In addition to saving time, the DR and scanning provided an important margin of safety for working on the difficult site. “The ability to keep our feet on the ground and safely measure remote objects is an impor- tant byproduct of the technology,” Cusick said. The team also collected long-range scanning data on the Kennicott Glacier, which lies adja- cent to the mine site. They measured to points on the glacier and conducted additional scans
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