What is LiDAR Technology and How does it Work?

LiDAR is an acronym for Light Detection And Ranging. LiDAR technology is a remote-sensing method that makes use of a pulsed laser to get information about surrounding objects. These laser pulses, combined with other data sets generate a 3-D map of the surveyed area.

LiDAR technology supersedes SONAR, RADAR, or cameras. The depth, speed, and dimension that it captures along with its ability to operate in dim light or no light conditions make it peerless.

LiDAR can pass through objects such as walls, water, or forest canopies making it useful for creating high-resolution digital elevation models with vertical accuracy of up to 10 cm.

A LiDAR mapping device is mounted onto an aircraft, automobile, or drone for scanning its environment. It has a laser scanner, a GPS, and an Inertial Navigation System (INS) to generate the 2-D or 3-D maps of the surrounding area.

Types of LiDAR

Broadly, LiDAR systems can be classified as Airborne LiDAR & Terrestrial LiDAR.

Airborne LiDAR

As the name suggests, such LiDAR systems are mounted on an aerial vehicle such as a helicopter or drone for scanning and mapping the surrounding area. As the airborne LiDAR emits laser pulses on the area to be scanned and mapped, the pulses are reflected upon hitting an object thus allowing exact measurement of its distance.

Airborne LiDAR is further classified as Topographic LiDAR and Bathymetric LiDAR.

Terrestrial LiDAR

Terrestrial LiDAR systems are positioned on the surface of Earth, on moving vehicles or tripods to create accurate LiDAR mapping. Such LiDAR systems find use in observing highways, analyzing infrastructure, or collecting point clouds inside and outside of buildings.

These LiDAR systems are of two types, namely Mobile LiDAR and Static LiDAR.

Despite the presence of several other technologies like GIS, and remote sensing, LiDAR finds extensive use across sectors because of its accuracy, speed, and wide applicability across a varied topography.

How Does LiDAR Work?

A LiDAR sensor operates by emitting pulsed light waves into its surrounding area.

These pulses return to the source when they encounter an object in their path.

The LiDAR sensor calculates the time the light wave takes to travel to and from the object to calculate the distance.

A source sends over 160,000 pulses/second to create a precise, real-time 3D map of the surrounding area.

For every second, a 1-meter pixel receives close to 15 pulses that cause LiDAR point clouds to create millions of points.

As LiDAR sensors, mounted on a plane, scan the area from side to side, pulses fall at all angles. While a few pulses strike directly below at nadir, most pulses travel off-nadir. The LiDAR sensor takes into account these angles while calculating elevation.

What Constitutes a Typical LiDAR System?

An airborne LiDAR system has 4 parts.

● LiDAR sensor: The sensor sends out laser pulses, mostly in the green or near-infrared bands, to scan the surrounding area.

● GPS Receiver: A GPS receiver tracks the altitude and location of the aerial vehicle. Tracking these metrics is important for accurate topographic and elevation values.

● Inertial Measurement Units (IMU): Aerial vehicles, especially airplanes, tilt as they travel.

IMUs track its tilt. LiDAR systems make use of the tilt to accurately measure the incident angle of the pulse.

● Data Recorders: As the LiDAR sensor scans the surrounding surface, a computer records the pulse returns to translate into useful data.

Where Does LiDAR Technology Find Use?

LiDAR technology finds use across several sectors. From autonomous vehicles to forestry and agriculture, several industries are increasingly adopting innovative technology.

Here are a few of the applications of LiDAR:

1. Agriculture — LiDAR is used in agriculture to scan fields and map areas with optimal sunlight. It can also be used to help trace crops that need water or nutrients.

2. Archaeology — This is an interesting application of LiDAR technology. Since LiDAR pulses can scan through walls and opaque surfaces, they can help experts discover hidden structures under the earth.

3. Astronomy — NASA (U.S. National Aeronautics and Space Administration) used LiDAR technology to explore the surface of Mars. Using LiDAR mapping techniques, NASA was able to create a topographic map and detect snowfall in Mars’ atmosphere.

4. Climate Change — LiDAR technology is used to study and track changes in the atmosphere, to track atmospheric gases, to study patterns in changes in vegetation/forest cover, or to calculate glacial movement over time and other changes in it.

5. Land Management — Land resource management is conventionally conducted through aerial surveys. The same can be sped up, with greater accuracy using LiDAR systems. They’re also useful in disaster assessment, emergency response (e.g., to fight forest fires), and location-based investigations.

6. Land Mapping — LiDAR is used to create accurate shoreline maps and digital elevation models for GIS by The National Oceanic and Atmospheric Administration (NOAA). It is also used during emergency response missions.

7. Oil and Gas Exploration — Since laser pulses have a shorter wavelength than other optical rays, LiDAR sensors can detect tiny molecules in the atmosphere. An advancement over LiDAR, called Differential Absorption LiDAR (DIAL), can trace oil and gas deposits.

8. Renewable Energy — LiDAR technology efficiently identifies the basic requirements for harnessing solar energy, such as optimal panel positioning or, calculating direction and wind speed for turbine placement in wind farms.

9. Robotics — LiDAR sensors are the driving force behind autonomous vehicles where they detect the distance between the vehicle and nearby objects in its surroundings. Robots with mapping and navigation capabilities are powered by LiDAR.

10. Tsunami Modeling — LiDAR sensors are part of early warning systems that warn people about any impending signs of dangers of tsunami. Using LIDAR, the seashore and underwater elevation can be determined. Combining the LiDAR data with GIS, experts can predict which areas will be worst affected by a tsunami.

Wrap Up

LiDAR is an optical remote sensing technology used to measure elevation and variable distances. Despite its similarity to SONAR and RADAR technology, it supersedes them all. For one, it lies in the optical range, and secondly, it can work far more effectively where all other technologies have limited application.

Owing to its speed, accuracy, and applicability in a wide range of circumstances, it is employed in several sectors for scanning and mapping to produce the desired results.

Nakshatech and its Team hold core expertise in scanning, mapping, and deciphering 3D LiDAR maps. Our team has helped businesses get the desired results with enhanced accuracy within a short duration, using LiDAR technology.

In addition to LiDAR scanning, our expertise in GPS and other remote sensing methods adds an edge to the whole procedure.

To know how your enterprise can benefit from Nakshatech’s LiDAR services, click here.