LiDAR (light detection and ranging) is an optical remote-sensing method that measures distances using laser light — similar to radar, but with light instead of radio waves. A LiDAR sensor emits up to millions of short laser pulses per second; these strike surfaces and are reflected. From the light's travel time (how long until it returns) and the known speed of light, the distance to each point hit is calculated.
Many such measurements produce a three-dimensional point cloud of the environment. The intensity of the returned light also makes it possible to distinguish materials, for example pavement from vegetation.
LiDAR is a key technology for autonomous vehicles and robots, which use it to detect obstacles, measure distances and localize themselves in their surroundings. Further fields of use include topographic surveying, mapping, and forest and coastal science. Depending on the design, the laser beam is steered across the scene mechanically or electronically (solid-state).