LIDAR

Definition
LIDAR (an acronym for light detection and ranging) is

"[a]n instrument capable of measuring distance and direction to an object by emitting timed pulses of light in a measured direction based on the time between when a pulse is emitted and when its echo is received. Three-dimensional information is computed by relating these distances and direction measurements to the location and orientation of the instrument. Airborne LIDAR instruments are used to develop three-dimensional data, such as digital elevation models, tree and building heights, and feature geometry."