Q2009Lidar times the return of laser pulses to build three-dimensional point clouds; pulses reaching ground through canopy gaps can expose subtle terrain and archaeological landscapes hidden by vegetation.
A lidar instrument sends rapid pulses and converts each round-trip travel time into distance. Aircraft or satellites repeat the measurement millions of times, assembling a point cloud of roofs, branches and ground. The light does not pass through solid leaves; enough pulses find small openings for analysts to separate canopy returns from terrain. Remove the digital forest and old roads, terraces or foundations can emerge without a spade entering the soil.