LiDAR Scanning: Complete Guide (How It Works, Types, Uses)

This guide explains, in plain language, what a LiDAR scanner is, the physics behind it, the four main families on the market, how Apple's consumer LiDAR sensor compares to a professional scanner, and what you actually do with the point clouds at the end.

What is a LiDAR scanner, technically

LiDAR is a remote sensing technology. NOAA classes it as an "active" sensor, by contrast with a passive sensor like a regular camera: an active sensor produces its own signal (here, a laser pulse) instead of relying on sunlight. The instrument fires a pulse of light, the pulse bounces off a surface, the receiver records the return.

Because light travels at a known speed, the round-trip time gives the distance from the sensor to the surface. Repeat that measurement hundreds of thousands of times per second, while a motorized mirror sweeps the laser across the scene, and each measurement becomes one (X, Y, Z) point in space. Stack the points and you get a point cloud: the raw 3D record of a building, a quarry, a city block or a vase.

The scanner does not know what a wall or a tree is. It only knows that a point sits at coordinates (X, Y, Z) and that the surface there reflected the laser with a certain intensity. If you want the underlying data structure, we covered it in detail in What is a point cloud: each point carries XYZ coordinates, often a color (when the scanner has a camera), often an intensity value, and on outdoor LiDAR often a classification (ground, vegetation, building).

How a LiDAR scanner works, step by step

Behind the simple time-of-flight formula, the actual scanning pipeline involves seven coordinated stages, from the laser diode firing the pulse to the file format the cloud lands in.

1. Emission. A laser diode produces a short pulse of light, typically in the near-infrared band. Per Wikipedia, 600 to 1,000 nm wavelengths are the most common for non-scientific applications. Bathymetric (water-penetrating) systems use a green 532 nm laser.
2. Steering. A rotating or oscillating mirror, or a more exotic optical assembly (Risley prisms on some airborne units), steers the pulse across the scene. This is what makes the scanner "scan" rather than just measure one point.
3. Reflection. The pulse hits a surface and a fraction of the light bounces back toward the sensor.
4. Detection. A photodetector records the return and a clock measures the round-trip time t.
5. Distance calculation. The instrument computes d = c * t / 2. Modern scanners process this in real time, hundreds of thousands of times per second.
6. Georeferencing. On mobile and airborne units, GPS/GNSS plus an inertial measurement unit (IMU) record the scanner's position and orientation at every measurement, so the raw distance can be turned into an absolute XYZ point in a real-world coordinate system.
7. Output. The end product is a point cloud, in a file format like E57, LAS, LAZ or a vendor-native format (RCS / RCP from Autodesk Recap, LGSx from Leica Hexagon).

Time-of-flight vs phase-shift

Two physical methods exist to turn a laser pulse into a distance. Time-of-flight measures the absolute time it takes for the pulse to come back. Phase-shift emits a laser whose intensity is modulated like a sine wave and measures how much the returning wave is phase-shifted relative to the emitted wave.

The four main families of LiDAR scanners

Wikipedia organizes LiDAR systems by the platform that carries them. The same categorization is used in the AEC and surveying industries. Each family trades accuracy, speed and coverage differently.

1. Terrestrial static (TLS)

A tripod-mounted scanner that you put down, level, and let spin a full 360 degrees to capture a station. You then move the tripod, capture another station, and register the stations together in post-processing. This is the workhorse of AEC and surveying because it delivers the best accuracy (Wikipedia notes vertical accuracy below 50 mm is achievable in survey configurations).

• Typical brands: FARO, Leica (Hexagon ecosystem), Riegl, Trimble.
• Workflow: tripod station, level, 360 degree sweep, move, repeat, register stations in post.
• Strength: highest accuracy of any LiDAR family, certifiable for as-built documentation.
• Constraint: each brand has its own native file format, which makes multi-vendor workflows painful without a platform that handles them natively.

2. Terrestrial mobile

The scanner is mounted on a platform that moves: a backpack, a trolley, a car, an autonomous robot. SLAM (simultaneous localization and mapping) algorithms let the system know where it is in real time, without needing a tripod station. You trade some accuracy for a lot of speed and coverage: a SLAM backpack will scan a building in an hour where a static scanner would need a day. Brands you will encounter: NavVis, Viametris, and again FARO and Leica which both have mobile lines.

3. Airborne LiDAR

The scanner is mounted on an aircraft, a helicopter or, more and more often, a drone. NOAA explains that airborne LiDAR fires a laser at the ground, the surface reflects the beam back, and the combination of GPS and inertial measurement on board turns the measurements into a topographic point cloud.

• Terrain elevation models (DTM / DSM) over large areas.
• Forestry inventories and biomass estimation under canopy.
• Archaeological surveys (LiDAR famously revealed Mayan cities under jungle canopy).
• Corridor mapping for power lines, roads and railways.
• UAV LiDAR for medium-area surveys where a manned aircraft is overkill but a tripod is too slow.

4. Bathymetric LiDAR

A specialized airborne variant that uses a green 532 nm laser instead of near-infrared, because green light penetrates water. NOAA describes it as the technology used to map seafloor and riverbed elevations. Wikipedia notes that bathymetric LiDAR works between roughly 0.9 m and 40 m of depth, with vertical accuracy in the order of 15 cm. It is the only LiDAR family that crosses the air-water interface; standard topographic LiDAR is fully reflected by water surface and is blind below it.

And the LiDAR in your iPhone Pro?

Apple shipped a LiDAR sensor on the iPad Pro 4th generation in March 2020, then on the iPhone 12 Pro in October 2020, and on every iPad Pro and iPhone Pro since. According to the Apple documentation summarized on Wikipedia, the stated uses are augmented reality and photo autofocus assistance, not professional surveying.

Concretely, the iPhone Pro LiDAR is useful to quickly capture a room, an object or a small scene with apps like Polycam, Scaniverse or 3D Scanner App. The point clouds it produces can be a good starting point for a quote, a sketch, a 3D print, an architecture preview. They are not a substitute for a survey-grade scanner when you need certified millimeter accuracy. Treat the smartphone LiDAR as an everyday utility, and the FARO or Leica TLS as a professional measurement instrument.

LiDAR vs photogrammetry vs radar

LiDAR is not the only way to produce a 3D point cloud. Photogrammetry triangulates 3D points from many overlapping photos. Radar uses radio waves instead of light. Each technology has a sweet spot.

In practice, many professional projects combine LiDAR and photogrammetry: drone photogrammetry for the overall colored site, terrestrial LiDAR for the buildings or zones that require certified accuracy.

What professionals do with LiDAR data

Once you have a clean point cloud, every industry has its own extraction workflow. Here are the most common professional applications, with internal links where ATIS.cloud already documents the workflow.

• Surveying and topography: as-found drawings, stockpile and excavation volumes, digital terrain models (DTM) and digital surface models (DSM).
• AEC and BIM: scan an existing building, compare scan vs BIM (called "as-built"), feed scan-to-BIM workflows. See also our guide what is scan to BIM.
• Industry: document a plant, monitor structural deformation between two scans, plan retrofits, train operators in VR or digital twin environments.
• Heritage and archaeology: archive a monument with millimeter accuracy, plan a restoration, build digital exhibits. Airborne LiDAR is famous for uncovering archaeological sites hidden under vegetation.
• Infrastructure: bridge inspection, road pavement analysis, railway clearance checks, tunnel monitoring.
• Forestry and agriculture: forest biomass estimation from airborne LiDAR, plant counts, terrain analysis under vegetation canopy.
• Automotive: LiDAR is one of the sensors used in autonomous and semi-autonomous driving stacks, alongside cameras and radar.

Files a LiDAR scanner produces

A LiDAR scanner generates a point cloud, and the file format depends on the scanner brand and the downstream software.

• E57 : open ASTM standard (E2807), the dominant interchange format, supported by virtually every scanner and viewer.
• LAS / LAZ : open ASPRS standards. LAZ is a compressed LAS. Reference formats for outdoor and airborne LiDAR.
• RCS / RCP : Autodesk Recap native formats, used heavily in AEC.
• LGSx : proprietary Leica Hexagon format.
• Legacy : PLY, OBJ, PCD, PTS, XYZ still appear in research or legacy workflows.

ATIS.cloud reads E57, LAS, LAZ, RCS, RCP and LGSx across all plans. The RCS and RCP support is native, without an Autodesk license required, which is unusual on the market. We covered the Leica format in detail in our dedicated LGSx guide.

How to view and share a LiDAR scan

Once the scanner has written its file, the two practical questions are: how big is it, and who needs to see it. A small E57 of a single room can sit on a USB key. A drone LiDAR survey of a quarry can hit hundreds of GB. A full industrial plant captured station by station can pass the terabyte threshold.

For desktop work on small or medium files, CloudCompare (open source) and Autodesk Recap (commercial) are the usual suspects. For large files or external sharing, the client opens a link, looks at the scan, measures, comments, sends back a screenshot with a markup. No 4 GB transfer over WeTransfer, no "can you install this software first" email.

ATIS.cloud is the platform we build for exactly this use case: an app 3D in the browser that handles scans up to 1 TB per file (5 TB of total workspace), reads natively every scanner brand on the market (FARO, Leica, NavVis, Riegl, Trimble, Viametris, Matterport, etc.), supports formats E57, LAS, LAZ, RCS, RCP and LGSx, with secure link sharing, sovereign hosting in 22+ countries, and a 14-day free trial without credit card.

A short history of LiDAR

LiDAR is older than most people assume. Wikipedia traces the first "lidar-like" system to Hughes Aircraft Company in 1961, with the Colidar Mark II rangefinder built in 1963.

• 1961 : first lidar-like system at Hughes Aircraft Company.
• 1963 : Colidar Mark II rangefinder.
• 1971 : Apollo 15 astronauts use a laser altimeter to map the Moon.
• 1990s-2000s : airborne LiDAR matures for civilian topography.
• 2000s : terrestrial laser scanning becomes mainstream in AEC and surveying.
• March 2020 : Apple ships LiDAR on iPad Pro 4th generation, then on iPhone 12 Pro in October 2020.

Today, the same underlying physics powers a heavy airborne survey rig and the sensor in your phone.