LiDAR lands on everyone's radar

By Cabe Atwell Jun 17, 2021 4:34pm

Genius as it may be, sometimes even the cleverest of technologies gets a slow start. Such has been the case with LiDAR—light detection and ranging—which is used to capture 3D images and information about both natural and manufactured objects and environments and their surface characteristics.

Though it was first developed in the 1960s, LiDAR didn’t gain traction until the 1980s, when the global positioning system (GPS) was introduced. Today, various types of LiDAR are used across numerous disciplines, such as architecture, agriculture, urban planning, climate change, construction, coastal engineering, archaeology, topography, national defense, space exploration, and so much more.

The remote sensing technology of LiDAR typically consists of a laser, scanner and GPS receiver. Light pulses via a laser are aimed at a target, and the light is reflected by the target. Sensors detect the reflected light and measure the range or distance between the LiDAR system and the target, as well as three-dimensional information regarding the surface around it.

To calculate the distance of the target, the following formula is used:

Distance of Target = (Speed of Light x Time of Flight) / 2

Once multiple laser ranges or distances have been captured, they can be coupled with GPS data and other measurements to form a “detail-rich group of elevation points, called a 'point cloud,” according to the National Oceanic and Atmospheric Administration. Point clouds can be used to create various models and tools that are useful in topography, urban planning, and other areas of study.

Two primary categories of LiDAR technology include airborne and terrestrial. However, various other types of LiDAR exist, and have proven useful to scientists in both the public and private sectors. Here’s a cursory list to illustrate the depth and breadth of this remarkable and adaptable technology.

Airborne: Just as it sounds, LiDAR systems can be installed on an aircraft or drone to capture data from certain elevations down to Earth’s surface, whether for topographic (terrain) or bathymetric (waterway) purposes.

Bathymetric: Using infrared light and “water-penetrating green light,” according to the NOAA, bathymetric LiDAR can measure the precise depth of rivers, lakes, oceans and other waterways, as well as provide information about the seafloor and riverbed elevations. This information is particularly useful for locating objects in waterways, as well as maintenance and emergency planning along riverbanks and coastlines.

DIAL: This form of the remote sensing technology stands for differential absorption LiDAR and is used to measure ozone in the lower atmosphere.

HSRL: Developed by NASA, HSRL, or high spectral resolution LiDAR, uses radio waves to determine the size, composition, distribution and of aerosols in the atmosphere.

Raman: Nope, it’s not your favorite bowl of broth-y noodles. From the ground, Raman LiDAR transmits “short pulses of UV laser light into the atmosphere” to capture water-vapor, temperature, aerosol and other properties.

Space-borne: Using satellite laser ranging and space-borne LiDAR applications, scientists can study the topography of planets in the solar system as well as the layers of Earth’s atmosphere.

Terrestrial (Mobile and Static): If you’ve ever used Google Maps or Google Earth, you’re familiar with mobile terrestrial LiDAR, which employs sensors, GPS and cameras mounted on moving vehicles and aircrafts to capture precise 3D data of terrain, streets and roadways. Static terrestrial LiDAR is primarily used for mining and archaeology, is portable, and captures cloud points from fixed locations.

Topographic: From a helicopter, drone or other aircraft, topographic LiDAR can be used to assess the terrain of an area for monitoring and/or mapping purposes. Applications include urban planning and coastal engineering to name just a couple.

Wind: While other methods to measure wind speed, direction and turbulence are typically difficult to apply and lead to inaccuracies, wind LiDAR uses low-noise laser light to capture precise data. As one example, this accurate data can be used to determine the location of and planning for wind farms.

Sources:

National Ocean Service

NOAA

What is lidar?

https://oceanservice.noaa.gov/facts/lidar.html

Geospatial World

What is LiDAR technology and how does it work?

https://www.geospatialworld.net/blogs/what-is-lidar-technology-and-how-does-it-work/

Geospatial World

Do you know how many types of LiDAR are there?

https://www.geospatialworld.net/blogs/do-you-know-types-of-lidar/

NKT Phototonics