Range measurement using transmitted laser light and its returned signal. For a pulse traveling a round trip in air, the elementary range is , where is the propagation speed and the measured travel time. Sensor position, pointing and time synchronization place returns in a three-dimensional point cloud. Scanning lidar can record multiple returns from vegetation and the ground; a return is an observation of a reflecting surface, not automatically bare-earth elevation.
Lidar acquired from an aircraft with surveyed trajectory and orientation. Ground-return classification removes canopy and structure returns before constructing a bare-ground digital elevation model. Penetration through forest is sampling through canopy gaps, not unrestricted transmission through leaves. Areas with few or no ground returns require uncertainty assessment rather than treating interpolated heights as observations.[ref]
What is the difference between lidar data and a digital elevation model by United States Geological Survey. Point-cloud returns from vegetation, structures and ground, and filtering to a bare-earth model
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Lidar, which stands for Light Detection and Ranging, is a remote sensing technology that uses laser light to measure distances to a target. This technique involves sending out laser pulses and measuring the time it takes for the light to return after bouncing off an object or surface. By calculating the time of flight of the laser pulses, Lidar can determine the distance to the target with high precision.