Planes, Trains and Automobiles. For those of us of a certain age, it’s a classic Steve Martin and John Candy road trip comedy. But add some lasers and precision positioning equipment… now we’re talking about some serious 3D mapping technology. And when we stopped in London for the FME 2012 World Tour, LandScope Engineering of the UK gave us a firsthand look at how they’ve incorporated FME into their Mobile Mapping System (MMS) workflow.
LandScope provides land and engineering survey and geomatics services in the UK and internationally. Knowing that 3D data – and point clouds, in particular –were gaining recognition as valuable and efficient methods for mapping, they invested in a TopCon IP-S2 and launched their autoMAP service.
The IP-S2 is a collection of sensors, each one providing different, sometimes redundant information that improves the accuracy of the overall dataset being produced. There are three high-res LiDAR scanners, sweeping lasers and capturing time-stamped data every 15 nanoseconds. The position of the vehicle is tracked by a dual frequency GNSS receiver while wheel encoders capture odometry information. The attitude (or pose) of the vehicle is monitored by an Inertial Measurement Unit (IMU), and the final touch is the digital camera capturing 360-degree spherical images at 15 frames per second. The entire system is portable, and easily adapted to different vehicles.
The beauty of mobile mapping is just that – the fact that it moves. Install it on a van, and you’re capturing precision data at highway speeds. Put it on a boat, and you’re measuring and visually recording the condition of the underside of a bridge or jetty. Mount it on a hi-rail, and you’re documenting railway track conditions, through tunnels and over bridges. It’s an amazingly efficient method of 3D data capture – LandScope drove and captured the entirety of Dublin’s central business area in just a couple of days.
The data collected is impressive, not only for its high degree of accuracy, but also for its sheer volume. Half the challenge is producing a usable, functional data product for the end user – and that’s where FME entered the picture for LandScope. With the assistance of FME experts STAR-APIC, they developed a post-processing workflow that gets the right data into the customers hands, and does it efficiently and accurately.
“One of the more significant challenges was the management of such large datasets within various coordinate reference systems,” says Tom Card, 3D Survey Services Manager. “We purchased FME initially for the purpose of reprojecting massive quantities of point cloud data from its native WGS84 datum to various local coordinate systems, and with a range of formats, including Ordnance Survey OSGB36.” The key was the GridInQuestReprojector Transformer, which handles 3D coordinate conversions strictly in accordance with established Ordnance Survey datum transformation standards.
Now that the basic requirements are well in hand, what’s next? As LandScope and their customers delve deeper into what can be done with point clouds, they’re starting to explore the latest and greatest point cloud functionality in FME. Customers are already saving huge amounts of time doing asset inventory based on the data, and Tom plans to push it further with tiling, clipping, and manipulation like intensity filtering – separating pavement markings from surrounding asphalt and organic material, for example.
In the meantime, FME is doing just what LandScope needs it to do. “FME has proven to be a robust step within our established mobile mapping workflow providing us with an efficient and quality assured method of delivering our data to a wide customer base. And at the end of the day, that’s what we’re looking for,” says Tom. We do like a story with a happy ending!
Learn more about FME’s point cloud and LiDAR support at www.safe.com/PointClouds.