By Paul Enneking, PLS
While mobile laser scanning has been around for several years, the limiting factor in its usability has been the data processing software. It was simply lagging in terms of processing the enormous amount of the raw data collected (“point cloud”) and providing something that the client could actually use.
Delivering the entire point cloud provided far too much data that often crashed clients’ computers when they tried to load it—the latest mobile laser scanners can capture up to 1.2 million points per second in raw data. Only recently has the point cloud processing software and the extraction software caught up with the data collection capability.
Mobile scanning technology has any number of highly useful applications. Using the same laser beam technology as static (tripod) scanners and aerial LiDAR scanners (Light Detection and Ranging), mobile scanners take it “out on the road” via trucks, railway cars, boats, or even ATVs.
One of the primary uses of mobile laser scanning is to survey roadways and highways. Driving along at highway speeds, the latest scanners can capture design-level survey data. With a few passes, we have the ability to create an accurate map of an entire roadway with all existing improvements: pavement, lane lines, cracks in the pavement, etc.
The benefits are substantial. Since survey crews do not have to work out on the roadway, safety is improved. Also it’s not necessary to close down a road to capture the data needed. Other uses include surveying transmissions lines; levees; railroad tracks; lakes, rivers and oceans; and even off-road locations like mines and tunnels.
Highly sophisticated software in an on-board computer simultaneously collects the data from onboard equipment that includes two overlapping laser scanners, two GPS antennas, an Inertial Measurement Unit, and a Distance Measurement Instrument. The software is working every instant as the mobile scanning vehicle moves along.
Extracting the Data
The collection of data, however, is just the start of the process. Once the raw scan data is gathered, the result is an enormous amount of 3D data points. Software is the key to processing this data to create a geo-referenced point cloud and then to extract from the point cloud the data files and design-level drawings that the client needs. In terms of time, creating the design-level deliverable can take 10 times the amount of time it takes to collect the data, but this still represents a big improvement in the software over the last few years.
Psomas has always had the reputation of being a technological leader in the surveying industry. However, for the last several years, we used subconsultant firms to collect our mobile scanning data. Now that the software has caught up with the capabilities of the hardware, it was time to make the investment ourselves. We just bought our own mobile laser scanner, the Lynx SG1 Mobile Mapper System from Optech.
Paul Enneking, PLS, is vice president and director of Northern California surveying and mapping at Psomas.