LiDAR boasts a range of benefits for the engineers, planners, analysts, consultants and project managers that use it but, how does it work? And how can it benefit your organisation’s projects?
In this article, we cover the basics of LiDAR so you can better understand its use cases and whether it can benefit your organisation.
This article covers:
- What is LiDAR?
- The benefits of LiDAR
- What you can use LiDAR for
- Types of LiDAR methods
- The differences between aerial vs terrestrial LiDAR
- Use cases of LiDAR
- LiDAR providers
What is LiDAR?
LiDAR, which stands for Light Detection and Ranging, is a remote sensing technique that uses a laser-based system to densely sample the surface being scanned to produce highly accurate location and height (x,y,z) measurements.
The sensor emits laser light pulses which reflect off the surfaces that they hit (vegetation, buildings, bridges etc). The ‘returns’ are recorded and generate a point cloud dataset. The point cloud can be managed, visualised, and analysed using various software tools.
The laser sensor combined with a GPS (Global Positioning System) and INS (Inertial Navigation System) allow for highly accurate measurements which have become a cost-effective alternative to traditional survey techniques.
Additional information is stored along with every x, y, and z positional value in the point cloud. This can include the strength of the return, the RGB (red, green, and blue) colour value, the scan angle, and scan direction.
In combination, this allows for some powerful use cases. For example, returned signal strength can be used to identify the reflectiveness of road signs or road markings. Post processing allows for further analysis making it possible to classify the point cloud, identify ground surface, buildings and roads, and vegetation.
What can you use LiDAR for?
There are many uses for LiDAR data, here are a few of the most common:
Roading engineers – Keep your crew safe, reduce travel, and save money on traffic management plans, with near survey-grade data that removes the need to do site visits or close roads for surveys.
Digital engineers – Detailed BIM compatible data at your fingertips to help you select and assess sites, extract key features, prepare plans and designs, and build simulations and 3D models for engagement.
Lines companies & utilities – Manage and maintain assets remotely and more efficiently. Conduct accurate surveys, rate lines, maintain inventories, classify features, and monitor vegetation encroachment.
Road safety specialists – Plan improvements to road infrastructure and manage signage locations without putting your crew at risk, with easy access to accurate data for almost all New Zealand roads.
Types of LiDAR methods
LiDAR can be executed in two methods: aerial and terrestrial.
Aerial LiDAR, as the name suggests, interprets ground data from the sky. To achieve this, a LiDAR sensor is attached to an aircraft: aeroplane, helicopter, or drone. The laser light is emitted toward the ground and returned to the moving airborne sensor.
Terrestrial LiDAR on the other hand, uses a sensor configured to work from land-based vehicles, a static instrument such as a tripod, or from a hand-held device such as the latest models of iPhones. In this discussion we’re going to focus on terrestrial LiDAR captured from vehicles.
While both have a similar construct, they each boast their own unique benefits and thus, have very clear use cases.
The differences between aerial vs terrestrial LiDAR
Aerial LiDAR
Aerial LiDAR provides an efficient way to capture land mass at speed where there is a direct view of pavements and building tops. A limitation of aerial LiDAR is simply that information is being captured from the air and at speed which means that the resolution of the data, the number of returns per metre squared is less than it might be from a stationary or terrestrial system. In addition, the height of the sensor above the ground provides low-density sampling of vertical faces such as buildings and embankments.
Use cases for aerial LiDAR
Aerial LiDAR is used by many industries from primary industries and construction to environmental protection and hazard management to produce Digital Elevation Models (DEM) and Digital Surface Models (DSM). They can depict where land or man-made structures rise and fall, to produce an accurate representation of the landscape.
Terrestrial LiDAR
Terrestrial LiDAR is similar in many respects to airborne LiDAR, but the sensor, GPS and INS, are configured to work from a land-based vehicle. This creates a highly accurate 3D point cloud of the environment at ground level. As the sensor is at ground level the returns collected by terrestrial LiDAR are different from aerial LiDAR of the same location. The number of returns per metre squared is much higher and building faces and embankments are directly captured. In addition, terrestrial LiDAR can scan surfaces that are obscured by aerial LiDAR such as tunnels and the underside of bridges and building awnings. The density of terrestrial LiDAR scans makes it possible to accurately identify road markings, streets signs, power poles and other road furniture, as well as use the point cloud to take near survey grade measurements from the comfort of the office.
Use cases for terrestrial LiDAR
The growth in the use of terrestrial LiDAR has been a game changer for engineering firms who are able to build 3D models faster. Road maintenance firms can find massive efficiency savings by spending less time on the road whilst at the same time improving crew safety. Central and local government can maintain their assets more effectively by knowing their exact location.
As we continue to think digitally, terrestrial LiDAR clearly offers new and more efficient ways of doing traditional processes.
LiDAR Providers
LiDAR data is a powerful way to capture surface level data. Used by many, LiDAR data can change how your organisation understands and interprets the features of the land that are important to their business.
At Abley, we’ve partnered with HERE Technologies to facilitate the distribution of HERE LiDAR Data in New Zealand. HERE LiDAR Data offers a more cost-effective and efficient approach to accessing LiDAR. Find out more about our HERE LiDAR Data offering.
Jacob Pescini
Associate Business Development Manager