LiDAR - Light Detection and Ranging

What is LiDAR?

A side-view of a cross-section of LiDAR data over an area with undulating topography (the edge of the Olifants Gorge, Kruger National Park, South Africa). Orange points outline the ground, white points outline vegetation growing among the rocky terrain.
 

LiDAR is a remote sensing technology that measures the structure of vegetation and topography of a landscape in three dimensions (3D). LiDAR operates like sonar, but with light instead of sound. A lidar sensor rapidly emits laser pulses that travel out to and reflect off of target objects (such as tree leaves, branches, grasses, and the ground). The LiDAR instrument records a “hit” when the emitted light pulse reflects off an object and returns to the sensor, producing a record of the location of that hit as a point in 3D space (with an x, y, and z coordinate). LiDAR instruments emit pulses at rates >100,000 times per second, enabling the measurement of millions of points (a “point cloud”) over the course of a UAV survey that outline the 3D structure of a landscape in great detail. 

A side-view of a LiDAR point cloud of a tree in Kruger National Park, South Africa, colored by height (blue = low, red = high)