Mobile Mapping and Geolocation

To know where mapped objects are on the surface of the earth, the mapping system needs some help from its onboard Global Positioning System receiver.

LiDAR Sensors Know What is Around Them

LiDAR sensors discover the characteristics of their surroundings and detect objects within it by using the return times of multiple lasers to map an area. Each return time is used to give the location of a specific point in space where an object is located, and the many millions of points together create a comprehensive picture.  

LiDAR Scanner

But the LiDAR only knows what the area that surrounds it is like, and where things are in relation to itself. Alone, it doesn’t know where it is in a geographical sense.  Imagine waking up in a room you’d never been in before – you’d be able to see what the room looks like, and the furniture it contains, but that wouldn’t tell you what city you’re in.  

Some more information is needed for the system to work out where it is in a global context.

How does the Digiflec Mobile Mapping System work out where things are on the surface of the earth?

LiDAR sensors are very good at seeing what is around them; that’s their job, after all! But to find out where the objects discovered are in geographical terms the Mobile Mapping System needs some help from a Global Navigation System (GNS), which is often referred to as a ‘Global Positioning System’ (GPS). 

The GPS receiver, which is carried on the mapping vehicle with the LiDAR sensors, knows where it is on the surface of the earth, using co-ordinates to describe its position. The LiDAR sensor produces a data file which contains information about the location of the objects it has discovered near it, and this information is added to the information from the GPS to give the location of the objects on the earth’s surface.  The resulting geospatial data is stored in a .las or .laz file.  Geospatial data plays a crucial role in understanding the world around us, helping us to solve complex problems, improve resource management and make informed decisions. 

These files are ‘vector’ format files. The .laz is a compressed form of the .las (LASer) format, which was designed specifically for the storage and exchange of LiDAR point cloud data. Developed in 2007, the .laz format was designed to reduce the file size of .las files, since LiDAR gathered data is extremely dense. The files contain massive collections of individual LiDAR points, each with its own set of characteristics, including X, Y and Z co-ordinates, intensity values and return numbers.  

Digiflec offer a mobile mapping service which gives high-density and highly accurate geospatial data to help you plan infrastructure projects more efficiently, streamline stakeholder communications and mitigate risk. LiDAR-based mapping systems gather geospatial data which is comprised of a collection of co-located charted points that can be recontextured as 3D models.

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