Have you ever watched one of those documentary television programs where researchers have a cool laser gizmo that spins on a tripod and maps the inside of a prehistoric cave or the outside of an ancient building like the Coliseum of Rome to the tiniest detail? Well, now the Memphis District has one of those gizmos too. But, our engineers and technicians are putting it to different uses.
Called the SX-10 Scanning Total Station, the device uses LiDAR to create a “point cloud” of a scanned object. LiDAR stands for Light Detection and Ranging. That’s a remote sensing method that uses light in the form of a pulsed laser to measure distances and locations. The Memphis District is already using LiDAR for mapping and imaging on our unmanned aerial vehicle (UAV). The SX-10, however, uses terrestrial LiDAR.
“Because the LiDAR is in a fixed location, it is able to give us very precise data,” Civil Engineer Bill Snapp said. “The UAV moves around and it is much harder to get the same degree of accuracy.”
Geodetic Technician Josh Beam explained the SX-10 has four settings for doing scans: coarse, standard, fine, and super fine.
“In most cases we scan at the standard setting,” Beam said.
The system produces higher resolutions by concentrating a greater number of light beams (sort of like pixels) within the same space. At each setting, however, the location of the features it scans is accurate within one millimeter. That’s about the thickness of a human fingernail. And it can do this from hundreds of feet away.
“By combining several scans we can get a three dimensional space view,” Beam said. “The system can automatically knit together scans from several locations to create a 3-D picture.”
Another useful feature of the new system is the speed that it operates.
“It scans 26,000 points (of light) per second,” Beam said. “It takes about 20-30 minutes to do a typical scan.”
Snapp said one way they plan to use the SX-10 is for Inspection and Evaluation (I&E) surveys.
“We do I & Es on flood walls, pump stations, culverts, and other structures,” he said. “And of course we’ll use it for topography.”
Snapp said his group will also be able to combine the data from terrestrial scans along with that obtained from their UAV and Global Positioning Satellite data for even better pictures.
“It’s just another tool in our toolbox,” Beam said. “But it gives us better data, does it faster, and improves the quality of our finished products.”