fidelity. With several setups of the SX10, Macrae produced dense point clouds registered to reference marks on the ship. “For most setups around the shipyard, I used full 360-degree scans with the SX10, but for finer details of Ceiba’s frame, I chose a smaller area with the poly- gon selection tool on the TSC7 [data controller],” he said. This yielded denser point clouds where more detail was needed while keeping the average setup time under ten minutes. “We had enough data to align the digital CAD model of the ship against the georeferenced point cloud,” Macrae said. Once the point cloud and CAD model were aligned, cross sections of each frame were plotted for as-built checking.” The team could see the cloud in Trimble RealWorks Viewer and online via Clarity. 3D animation allowed them to compare the cloud with the original design. Doggett says she doesn’t know of any other wooden ships of this size scanned this way while under construction. “I had seen other scans after a ship had been com- pleted, but there was a lot of detail missed. This gave us a unique way to see how well we were sticking to the design.” The End When we interviewed Doggett in April 2020, 75 percent of the frames were in place and planking would begin by fall. “We have been given a way of looking at and measuring things that we’ve never had be- fore,” Doggett says, “and are very grateful to Damian for helping make this happen.” For Macrae, it was more than a wonderful holiday to a place he’d al- ways wanted to visit. It was an opportunity to test the equipment his customers are fast adopting. “Scanning Ceiba, the shipyard, the tide- lands and generating the topo plan from point cloud data was a good exercise on how much we can do with the SX10,” said Macrae. “We have TBC, and it was easy to extract features from the point cloud. It is a good example of mixing traditional topo points with data from a point cloud.” As the principal structure of the ship nears completion and other con- struction begins, Doggett says she is reaching out to new investors. As framing is finalized, she adds, another scan would be greatly wel- comed, too. Anyone interested in pitching in on a once-in-a-lifetime surveying adventure?
“There might be minor variations in the tide beds before the ship is complete, but the 3D model gives us confidence that the launch will go smoothly,” Doggett said. The Map Sailcargo’s jungle shipyard had grown organically, with structures built as needs arose. Prior to Macrae’s visit there was no formal map of the property, terrain, or structures. Macrae provided one using SX10 scan data gathered in just a day and a half of fieldwork. Areas not suit- able for scanning, such as break lines and features in tall grass, were observed traditionally with a range pole and an R10 or SX10. Macrae traversed around the shipyard with the SX10, taking a full dome scan at each setup. Each scan, including image capture (used for automatic point colorization and panorama creation in TBC), took just under 15 minutes and captured an average of 120 megabytes of data, with 8-10 million points each. Macrae collected nearly 40 scans in total before combining the scan data, RTK, traditional total station ob- servations and soundings into a single TBC project. From this dataset, TBC automatically extracted ground, building, power-pole, and tree points. With the bulk of processing on the massive data set completed automatically, Macrae needed roughly two hours to clean up the point cloud and create regions of interest such as Ceiba’s frames, specialty buildings, and fences. With the processing complete, it was a simple task to plot contour lines, building footprints, fences, road edges, and utilities. Macrae produced a topographic plan that can be used for planning, drainage design, and logistics. He also used Trimble Clarity to create a 3D fly-through of the site and true color point cloud views, enabling the team to view it online and share it with investors and partners. “We had never been able to view our camp in this manner before,” said Doggett. “We were not sure where our facilities were relative to the boundaries.” The Ship At the time Macrae visited, Ceiba’s keel was down and 13 of the ship frames were in place. Although Sailcargo makes hand measurements as the ship is constructed, a scan would allow them to check design
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csengineermag.com
may 2021
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