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An Introduction to LIDAR

Tamara Wilhite is a technical writer, industrial engineer, mother of two, and published sci-fi and horror author.

What Is Lidar?

RADAR stands for Radio Detection and Ranging. Radar relies on radio waves or RF to detect the speed, angle and distance of targets. Lidar is a modification of the well-known term radar, though it was developed two decades later. Lidar is not a form of radar. Instead, it is a detection system that uses the same principles of radar but uses lasers or light instead of radio or RF signals. That is why Lidar or LiDAR stands for Light Detection and Ranging.

Radar uses RF signals, while Lidar relies on light.

Radar uses RF signals, while Lidar relies on light.

How Does Lidar Work?

Lidar systems don’t receive reflected sunlight. Instead, they generate a pulse of light and wait for the light signal to return. It uses the return time to calculate how far away the land feature is beneath it. Lidar becomes less accurate the more distant the target is. This can be because water in the atmosphere can interfere with the signal, plants absorb some of the signal, and the travel speed of the vehicle carrying it can cause reflected signals to travel at an angle. Lidar systems compensate by sending many data points that are consolidated to create an image. Lidar systems could send up to a million pulses a second.

How Is Lidar Used?

Lidar systems combined with GPS receivers are carried underneath airplanes, drones and helicopters to create precise, 3D maps. Topographical Lidar, Lidar that maps land, uses near-infrared lasers with wavelengths of 900 to 1060 nanometers. Bathymetric LIDAR maps water-features like rivers, marshes, and the shallow sea floor. That type of Lidar uses green light at roughly 500 nanometers that can penetrate the water. This explains why Lidar is regularly used for surveying.

DEM or digital elevation model specifically refers to the capture of elevation data. That information is needed to build roads and bridges.

The information from Lidar surveys is used to map flood plains, create flood models and determine flood risk. It can track variations in material density, so it can track slope changes and coastal erosion.

Lidar can be utilized when we want to determine the amount and type of plant cover in an area. The reflective pattern of trees in bloom is very different from grassy plains. Lidar can be used to track invasive plant species and the health of an ecosystem. The information from Lidar systems can be used to monitor coastal erosion and how much carbon a forest is absorbing.

Furthermore, Lidar allows for the accurate classification of land use. It helps planners determine which land is subject to farming, ranching, human habitation or remains wild. Lidar can help planners track the impact of human activity and determine which areas remain wild and should be off-limits to development. They can also see which areas are less productive and allowed to re-wild.

Lidar is being adopted quickly in the forestry industry. Lidar is starting to be used to map the amount of dead wood available to potential forest fires so that fire departments can engage in proactive fire management. Lidar also allows them to determine where trees are overcrowded or dying so that they can be removed before an infestation spreads or wood quality declines.

Elevation maps from Lidar and sunlight exposure area maps can be used by farmers to determine which area will have the highest yield. The data on how well vegetation is growing allows farmers to determine which spots need fertilizer and which are doing fine. The same sort of data analysis is used to determine the best locations for solar panels.

Because Lidar is both precise and pierces vegetation, it can often detect things hidden by vegetation. This explains why Lidar is increasingly utilized in archeology, though it is supplemented by ground penetrating radar.

Ground penetrating radar antennas

Ground penetrating radar antennas

Lidar’s ability to map an area quickly has led to it being used to map crime scenes with minimal disruption to traffic.

The ability to detect the molecules near the surface mean it can aid in the discovery of mineral deposits. This is why Lidar is regularly used in the oil and gas and mining industries.

One of the most promising applications for Lidar is in self-driving cars. Lidar isn’t new to the automobile industry. Lidar has been utilized by cruise control systems to maintain the set speed while the driver guides the vehicle. Lidar is now being used to replace the driver. Self-driving cars are using basic Lidar scanners to detect obstacles and navigate streets. Like the cruise control systems, it measures the changes in vehicle speed, such as when it needs to slow down as it goes downhill. The LIDAR system also looks out for erratic movement in surrounding cars so that it could theoretically slam on the brakes before they hit. However, LIDAR cannot do the job on its own. Lidar systems cannot read traffic signs or traffic lights. This is why self-driving cars need visual cameras and radar, as well.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

© 2019 Tamara Wilhite

Comments

Tim Truzy from U.S.A. on February 25, 2019:

Interesting article, Tamara. Lidar has many promising advantages for science and the ordinary person. I saw on a science show how lidar helped archaeologists discover a previously unknown ancient city in Peru.

Recently, I read about the invention of flying cars, which manufacturers hope to bring to the public. Maybe they will use this technology.

In any case, you explained the technology well and provided a useful article for those curious about the topic.

Thank you.

sincerely,

Tim