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Lidar

Definition

Lidar (Light Detection and Ranging) is an active remote-sensing technology that measures distances by emitting laser pulses and timing their return from surfaces. Airborne lidar produces dense point clouds from which terrain (DTM), surface (DSM), and canopy models can be derived; terrestrial and mobile lidar capture detailed 3D scans of buildings, infrastructure, and interiors. Multiple returns allow penetration of vegetation to estimate ground and canopy structure. Attributes like intensity and waveform add material and vertical-structure clues. Accuracy depends on GPS/IMU integration, calibration, flight altitude, scan angle, and ground control. Point classification separates ground, vegetation, buildings, and noise. Lidar underpins precise topography, flood modeling, forest inventory, and as-built verification.

Application

Cities model stormwater and plan curb ramps with centimeter-level DTMs. Utilities map transmission corridors and vegetation clearances. Forestry estimates biomass and habitat complexity. Cultural-heritage teams reveal hidden archaeological features under canopy. Autonomous vehicles and robots use lidar for navigation and obstacle detection. Construction sites compare scans to BIM for progress monitoring.

FAQ

How do you choose point density?

Match density to the smallest feature you need to resolve—narrow channels or roof edges demand higher pulses per square meter. Consider budget and processing time.

What’s the difference between discrete-return and full-waveform lidar?

Discrete systems record a few peaks per pulse; full-waveform retains the entire energy profile, improving vertical structure analysis at the cost of larger data volumes.

Can lidar see through water?

Standard near-infrared lidar is absorbed; bathymetric lidar uses green wavelengths to penetrate clear water and map shallow bathymetry and shorelines.

How should point clouds be shared?

Use LAZ for compression, include classification and CRS metadata, and provide derived rasters (DTM/DSM) for users who do not need raw points.