Light Detection and Ranging

Light Detection and Ranging (LiDAR) is a remote sensing method that uses light in the form of pulsed laser to measure ranges or variable distances. LiDAR works much like radar or sonar which use sound or radio waves to discover something which cannot be seen. Except LiDAR uses light, in the form of lasers, which reflect back to the LiDAR device and allow that device to build a three dimensional map. LiDAR is used by geographers, atmospheric scientists, oceanographers, factory robots and self-driving cars.

In 1960, Theodore Maiman built and demonstrated the first practical laser, which was used in 1962 by MIT scientists to measure the distance between the Earth and the Moon with a reflected laser beam. In 1965, Stanford Research Institutes Ronald Collins filed a patent for the laser-radar, LiDAR, system to study Earth's atmosphere and weather. In 1969, Daniel Hickman and John Hogg published a scientific paper describing how airborne LiDAR could be used for measuring ocean depth.

In 1971 Lidar was used by Apollo 15 astronauts to map the Moon's surface. In 1974, Alan Carswell of York University in Toronto invents a laser range-finder which perfects the possibility of scanning a laser remotely to make maps. The first textbook on LiDAR was published in 1976.

In 1985, Optech, Alan Carswell's company, begins selling the Larsen-500, one of the earliest commercial LiDAR systems.

NASA brought LiDAR into space on the Space Shuttle Discovery in 1994 to study Earth's atmosphere from space in an experiment called LITE. In 2008 NASA's Phoenix Lander brought an Optech Lidar scanner to Mars to study the planet's atmosphere.

In 2005 LiDAR systems were used as the eyes behind self-driving cars in the United States military's DARPA Grand Challenge. Darpa announced in 2015 the creation of Sweeper, a miniature Lidar system. Sweeper stands for Short-Range Wide-field-of-view Extremely agile Electronically steered Photonic EmitteR.

In the use cases for geographic, oceanographic or atmospheric study, LiDAR is used with a specialized GPS receiver often from an airplane or helicopter to acquire data over broad areas. In these studies, there are two types of LiDAR: topographic and bathymetric. Topographic LiDAR uses near-infrared lasers to map the land. Bathymetric Lidar uses water-penetrating green light to measure seafloor and riverbed elevations.

The National Oceanic and Atmospheric Administration is using LiDAR to produce accurate shoreline maps, make digital elevation models for geographic information services and to assist in emergency response operations.

LiDAR can also be used in land management and planning, hazard assessment (including lava flows, landslides, tsunamis and floods), forestry, agriculture, geologic mapping, watershed and river surveys, measuring gases and particulates in the atmosphere, archaeological survey, climate monitoring, city planning, meteorology and mining.

LiDAR is being used to develop autonomous vehicles, as it offers computer-friendly data in the form of exact measurements which allows the vehicle to respond the terrain around. Cameras can deliver similar detail but require machine-learning software to translate the 2D images into 3D understanding and Radar systems don't offer the necessary resolution.

LiDAR allows vehicles to create a comprehensive 3D map of the terrain around it and an attached computer would be able to distinguish the objects from one another and respond to the difference between a truck or a child. However, LiDAR is unable to read signs and they can be disrupted in the case of limited visibility, and the current suggestion would be to use LiDAR with a camera system in those cases.