Types of lidar: airborne, terrestrial, mobile and bathymetric lidar systems compared
Key takeaways
- Lidar types are classified mainly by platform: airborne, terrestrial, mobile and bathymetric, plus satellite lidar.
- Terrestrial laser scanners give the highest accuracy, typically millimetres at short range; airborne lidar covers the largest areas at centimetre to decimetre accuracy.
- Bathymetric lidar uses green light (around 532 nm) because it penetrates water, while topographic lidar normally uses near-infrared wavelengths.
- Pulsed time-of-flight, phase-shift and frequency-modulated continuous-wave (FMCW) are the three main lidar ranging methods.
- Radar uses radio waves that pass through cloud and some materials; lidar uses light and gives much finer resolution.
What are the main types of lidar?
The main types of lidar are airborne, terrestrial, mobile and bathymetric systems, grouped by the platform that carries the sensor and the surface being measured. Each type is a complete lidar system: a laser, a receiver, a scanning mechanism, a timing unit and a way of knowing the sensor's position and orientation.
Lidar stands for light detection and ranging. In simple terms, what is lidar technology? It is a method of measuring distance by sending laser light to a surface and timing the reflection, repeated hundreds of thousands to millions of times per second to build a 3D point cloud. Our introduction what is lidar covers the basic principle; here we compare the types so you can see which one suits a project.
| Type | Platform | Typical accuracy | Typical coverage | Main uses |
|---|---|---|---|---|
| Airborne topographic | Aircraft, helicopter, drone | About 3–15 cm vertical | Hectares to thousands of km² | Terrain models, forestry, flood mapping, corridors |
| Bathymetric / topobathymetric | Aircraft or drone with green laser | Decimetre level, depending on water | Coastlines, rivers, shallow seabed | Coastal zones, river channels, habitat mapping |
| Terrestrial (TLS) | Static tripod | Millimetres at short range | A room to a building or plant | BIM, plant, heritage, deformation monitoring |
| Mobile (vehicle) | Car, train, boat with GNSS/INS | Centimetre level in good GNSS | Kilometres of road or rail per day | Roads, rail, street assets, city models |
| Handheld / backpack SLAM | Operator on foot | About 1–3 cm relative | Buildings, tunnels, forests | Indoor mapping, mines, quick as-builts |
| Satellite | Earth-orbiting spacecraft | Varies; designed for science | Global profiles | Ice, forest height, global elevation |
What is aerial lidar and how does it work?
Aerial lidar is a laser scanner mounted on an aircraft or drone that sweeps the ground below while a GNSS receiver and inertial measurement unit (IMU) record the sensor's exact trajectory. Combining range, scan angle and trajectory gives coordinates for every return.
An aerial lidar sensor typically uses near-infrared light and fires from hundreds of thousands to over a million pulses per second. A key advantage is multiple returns: one pulse can reflect partly from leaves, branches and finally the ground, so aerial lidar scanning can model bare earth beneath forest canopy. That is why it dominates national elevation programmes and flood modelling.
There are two scales of airborne work:
- Manned aircraft: large areas, higher altitudes, and quality levels such as those in the United States Geological Survey (USGS) lidar base specification. Its widely used Quality Level 2 calls for at least 2 points per square metre and 10 cm vertical RMSE in non-vegetated areas.
- Drone lidar: smaller sites at much higher point density, flown lower; see our guide to survey drones and UAV mapping for payload choices.
Much public airborne data is free. For lidar download in the United States, the USGS 3D Elevation Program (3DEP) provides national coverage, and the 3DEP LidarExplorer viewer lets you find and download tiles. Many other countries publish similar national datasets.
What is bathymetric and topobathymetric lidar?
Bathymetric lidar measures the depth of water and the shape of the bed beneath it by using a green laser, typically around 532 nm, which penetrates water far better than near-infrared light. Topobathymetric lidar combines a near-infrared channel for land with a green channel for water, mapping the land-water boundary seamlessly.
The system records a reflection from the water surface and another from the bed; the time difference, corrected for refraction and the slower speed of light in water, gives depth. Depth penetration depends strongly on water clarity: in clear coastal water it can reach tens of metres, while in turbid rivers it may be only a few metres or less.
Typical uses include coastal erosion monitoring, harbour approaches, river channel and floodplain models, and habitat mapping. Where water is murky or deep, multibeam sonar from a boat is the usual alternative.
What is terrestrial lidar and what is a lidar scanner on a tripod?
Terrestrial lidar is laser scanning from a static tripod position on the ground, and it gives the highest accuracy and density of any lidar type. A terrestrial lidar scanner rotates horizontally while a mirror deflects the beam vertically, covering nearly a full sphere at each setup.
Several setups are registered together into one point cloud. Accuracy is typically millimetre level at short range, which makes terrestrial lidar 3D laser scanning the standard for BIM, structural checks, industrial plant and heritage. Our terrestrial 3D laser scanner captures up to 2 million points per second in a 4.4 kg body, with range versions of 70 m and 150 m (on white, 90% targets) and a long-range version, plus HDR colour. For large sites, our high-speed terrestrial laser scanner scans at up to 1000 kHz over a 360° × 282° field of view with an eye-safe Class 1 laser.
Where scan data must sit on precise survey control, such as tunnels and monitoring, a scanning total station combines total-station angles and distances with 3D scanning in one instrument. The full static workflow is described in our article on terrestrial laser scanning.
What is mobile lidar? Vehicle, backpack and handheld systems
Mobile lidar is laser scanning from a moving platform, such as a vehicle, train, boat, backpack or handheld unit, while the system continuously calculates its own trajectory. Vehicle systems use GNSS and a high-grade IMU; handheld and backpack systems rely mainly on simultaneous localization and mapping (SLAM).
- Vehicle mobile mapping: roads, rail and street assets captured at traffic speed. Accuracy is centimetre level with good GNSS, but degrades in urban canyons and tunnels unless control points are added.
- Backpack and handheld SLAM: buildings, mines, forests and anywhere without GNSS. Our handheld SLAM laser scanner weighs 925 g, measures from 0.1 to 70 m and gives a point-cloud thickness of 1 cm or better after post-processing.
Lidar mobile mapping trades some accuracy for speed: a building that needs a day of tripod setups can often be walked in under an hour. Our explainer what is SLAM describes how these systems track themselves and control drift.
What are lidar components and ranging methods?
Every lidar scanning system has the same core lidar components: a laser emitter, a beam-steering mechanism, a receiver, precise timing electronics, and a positioning system. How the lidar measurement of distance is made differs between three ranging methods.
- Lidar emitter: a pulsed or continuous laser, commonly 905 nm, 1064 nm or 1550 nm for topographic work and 532 nm for water.
- Scanner: rotating mirrors, prisms or rotating heads; some newer sensors are solid-state.
- Receiver: the lidar laser sensor (photodetector) that records returning light and its intensity.
- Position and orientation: GNSS/IMU on airborne and vehicle systems, SLAM on handheld units, or a fixed setup for terrestrial scanners.
| Ranging method | How it measures | Typical strengths |
|---|---|---|
| Pulsed time-of-flight | Times each pulse's round trip | Long range, multiple returns; airborne and long-range scanners |
| Phase-shift | Compares phase of a modulated continuous beam | Very high speed and low noise at short to medium range |
| FMCW | Measures frequency difference of a chirped beam | Measures velocity too; emerging in automotive sensors |
Lidar resolution, the smallest detail a system can separate, depends on point spacing, beam divergence (the spot size at range) and range noise, not on point rate alone.
Radar vs lidar: what is the difference?
Radar uses radio waves and lidar uses light, so radar sees through cloud, rain and some materials but with coarser resolution, while lidar resolves fine detail but is blocked by fog, heavy rain and solid surfaces. Lidar wavelengths are around 1 micrometre; radar wavelengths are millimetres to metres.
| Criterion | Lidar | Radar |
|---|---|---|
| Signal | Laser light (visible or near-infrared) | Radio or microwave |
| Resolution | Millimetres to centimetres | Generally coarser |
| Weather | Reduced by fog, rain, dust | Largely unaffected |
| Penetration | Through gaps in vegetation; green light into water | Into soil, concrete or ice for ground-penetrating radar |
| Survey use | 3D mapping of surfaces | Subsurface and satellite deformation mapping |
In surveying, a radar survey usually means one of two things: a ground radar survey with ground-penetrating radar (GPR, also called a georadar survey) to locate buried utilities and voids, or satellite radar interferometry to measure ground movement. Neither replaces lidar; they measure different things.
How to choose a lidar type, software or lidar services provider
Choose the lidar type from the accuracy, area and environment of your project; then check that your lidar software can process and deliver the data in the formats your clients use.
- Define accuracy: millimetres point to terrestrial scanning; centimetres to mobile or drone lidar; decimetres to manned airborne.
- Define area and shape: rooms and buildings (terrestrial or SLAM), sites (drone), corridors (mobile or VTOL drone), regions (aircraft).
- Consider the environment: vegetation, water, GNSS availability and access.
- Plan control: GNSS and total station control is what ties all lidar types to a project grid.
- Check processing: lidar processing software for registration, classification and modelling; lidar mapping software and lidar GIS tools for terrain products and analysis.
Many firms buy terrestrial or handheld scanners for daily work and use lidar mapping services for airborne or bathymetric projects, where aircraft and specialist sensors make outsourcing more economical. To compare scanners for your lidar scanner applications, request a quote with your typical project size and accuracy requirement.
Frequently asked questions
What is the difference between radar and lidar?
Radar sends radio waves and lidar sends laser light. Radar works through cloud and rain and can penetrate the ground in the form of ground-penetrating radar, but its resolution is coarser. Lidar measures surfaces in fine detail and can map ground under vegetation through gaps in the canopy, but fog, rain and dust reduce its range.
What is ladar?
Ladar stands for laser detection and ranging. It is an older term, used mainly in military and defence contexts, for the same principle as lidar: measuring distance by timing reflected laser light. A ladar sensor and a lidar sensor work in the same way; in surveying and mapping the word lidar is now standard.
How far can lidar detect?
It depends on the type. Handheld SLAM scanners typically reach tens of metres, terrestrial scanners from about 70 m to several hundred metres, and long-range terrestrial and airborne sensors well beyond that, with aircraft flying at hundreds to thousands of metres above ground. Range falls on dark, wet or angled surfaces and in fog, rain or dust.
Lidar vs laser scanning: what is the difference?
There is no real difference in principle: a 3D laser scanner is a type of lidar system. In practice, people say laser scanning for tripod and handheld survey scanners and lidar for airborne, mobile and automotive sensors. A simple lidar range finder measures one distance, while a laser scanner sweeps the beam to capture millions of points.
Which type of lidar is most accurate?
Terrestrial laser scanning from a tripod is the most accurate type, typically reaching millimetre level at short range, because the instrument is stationary and close to the surface. Mobile and drone lidar usually achieve centimetre level, and manned airborne lidar a few centimetres to decimetres, depending on altitude, GNSS quality and calibration.
Can lidar see through water?
Standard near-infrared lidar is mostly absorbed or reflected at the water surface, so it cannot map underwater terrain. Bathymetric lidar uses green light around 532 nanometres, which penetrates water, and can map the bed to depths that depend on clarity, from a few metres in turbid rivers to tens of metres in clear coastal water.
Is lidar data free to download?
Much public airborne lidar is free. In the United States, the USGS 3D Elevation Program provides national coverage that you can search and download through its online viewers, and many other countries publish national elevation data too. Check the date, point density and accuracy of public data before using it for engineering design.
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