LiDAR

LiDAR, short for light detection and ranging, is a remote sensing technology that measures distance by firing laser pulses at a surface and timing how long the reflected light takes to return. Repeated millions of times, those measurements build a detailed three-dimensional record of terrain, vegetation, buildings and water.

History of LiDAR

LiDAR rests on the laser, so it could only appear after that device did. The Nobel Committee for Physics noted in 1964 that the possibility of an optical maser, or laser, was analyzed in 1958 and that the first laser was operating two years later.

Ranging with light is simple in principle, because distance follows from the time a pulse needs to travel to a surface and back. What turned that idea into a mapping method was pairing the laser with a scanner and with satellite positioning, so every measurement could be tied to a place on Earth. NOAA describes an airborne LiDAR instrument as consisting principally of a laser, a scanner and a specialized GPS receiver.

LiDAR later moved into orbit. NASA’s ICESat-2 satellite, launched on September 15, 2018, fires 10,000 laser pulses per second, compared with 40 per second on the first ICESat mission. A separate instrument called GEDI was mounted on the International Space Station to measure the structure of forests and topography.

How LiDAR works

A LiDAR system points a pulsed laser at a target, and a sensor records the light that bounces back. Because light travels at a known speed, the delay between sending and receiving a pulse gives the range. Each millionth of a second of round-trip delay equals about 150 meters of distance.

A range by itself is only a distance. NOAA explains that the ranges are combined with position and orientation data from an integrated GPS and inertial measurement unit, along with scan angles and calibration data. The result is a dense set of elevation points called a point cloud, in which every point has a latitude, longitude and height for the spot where a pulse was reflected.

Point clouds are then processed into other products, including digital elevation models, canopy models, building models and contours. A digital elevation model is a gridded map of ground height that can be used in geographic information systems.

Space-based LiDAR faces a harder signal problem. ICESat-2 sends about 300 trillion photons toward the ground with each pulse, and only about a dozen return to its telescope. Its detectors count individual photons, and filters tuned to the laser’s 532 nanometer green wavelength keep reflected sunlight from swamping them. The beam is also split into six, so the satellite samples several ground tracks at once.

Types of LiDAR

The two types NOAA names are topographic and bathymetric LiDAR. Topographic systems typically use a near-infrared laser to map land. Bathymetric systems use water-penetrating green light, so they can also measure the elevation of seafloors and riverbeds.

Platforms differ as much as wavelengths do. Airplanes and helicopters are the most commonly used platforms for covering broad areas, according to NOAA. Spacecraft such as ICESat-2 carry laser altimeters that measure elevation along their orbital tracks, while GEDI concentrates on the vertical structure of forests.

Despite these differences, most systems share the same core parts: a laser, a scanner and a positioning receiver. The type of system is therefore defined mostly by its wavelength and by the vehicle that carries it.

Applications of LiDAR

NOAA scientists use LiDAR products to model inundation and storm surge, to map shorelines, to support emergency response, to carry out hydrographic surveys and to analyze coastal vulnerability. The agency also uses the data to build more accurate shoreline maps and digital elevation models. LiDAR datasets for many coastal areas can be downloaded from NOAA’s Digital Coast portal, which makes the data available well beyond the agency itself.

The same measurements support land surveying, because a point cloud records ground height with a precision that earlier field methods could achieve only point by point.

In space, ICESat-2 measures the elevation of ice sheets, glaciers, sea ice, tree canopy height and ocean height in three dimensions. NASA says this helps scientists investigate why, and by how much, Earth is changing in a warming climate. Researchers have also developed a way to estimate near-shore seafloor depth from the satellite’s data alone.

GEDI addresses a different gap. Its laser ranging provides high-resolution measurements of the three-dimensional structure of tropical and temperate forests, including the forest canopy, which is hard to measure over large areas from the ground.

Advantages and disadvantages of LiDAR

NOAA highlights accuracy, precision and flexibility as the main strengths. A single survey can produce millions of elevation points, each with its own coordinates, and aircraft can cover broad areas in one campaign. Bathymetric systems add the ability to see below the water surface in places where light can reach the bottom.

There are trade-offs. The raw output is a point cloud, which must be processed before it becomes a map or model that most users can work with. Coverage depends on flights or satellite passes, so a dataset is a snapshot of one period rather than a continuous record.

Signal strength is another limit. The ICESat-2 example shows how few photons return from a very bright pulse, and sunlight reflected from the ground acts as noise that the instrument must filter out. Wavelength choice also forces a compromise, because a near-infrared system suited to land is not the right tool for the seafloor, which needs green light.

LiDAR vs. radar

LiDAR and radar both measure range from the time a signal takes to return, but they use different parts of the electromagnetic spectrum. Radar uses radio waves, while LiDAR uses light from lasers, such as the near-infrared and green wavelengths described above.

Because light has a much shorter wavelength than radio waves, LiDAR can resolve smaller features and produce denser point measurements. Radar, in turn, is better suited to situations where light would be blocked. The two methods are often seen as complements rather than competitors.

Editorially reviewed by Specialty Digest Editorial TeamLast reviewed November 4, 2026Researched and drafted with AI assistanceReport an issue