Light detection and ranging (LIDAR) is a technology used to create high-resolution models of ground elevation with a vertical accuracy of 10 centimeters (4 inches). The LIDAR is an active optical sensor that transmits laser beams to a target as it moves through specific topographic routes. The LIDAR sensor receivers detect and analyze the laser reflection from the target. These receivers record the precise time from when the laser pulse left the system until it returned to calculate the range distance between the sensor and the target.
In combination with positional information (GPS and INS), these distance measurements are transformed into measurements of real three-dimensional points of the reflecting target in the object's space. Light detection and ranging, or LIDAR, is a remote sensing technology that uses pulsed laser energy (light) to measure ranges (distance). Engineers and Earth scientists use LIDAR to precisely and precisely map and measure the natural and constructed features of the Earth's surface, inside buildings, underground and in shallow water. It has broad applications in many sectors, such as engineering and public safety.
The acronym LiDAR is often used to name this method of remote sensing. It uses light to measure distances and is also known as laser scanning or 3D scanning. The Doppler LIDAR and Rayleigh Doppler LIDAR are used to measure temperature and wind speed along the beam by measuring the frequency of backscattered light. Like airborne LIDAR systems, mobile systems usually include a LIDAR sensor, cameras, a GPS (Global Positioning System) and an INS (inertial navigation system).
A wide variety of LIDAR applications exist, in addition to the applications listed below, as often mentioned in national LIDAR dataset programs. Most bathymetric LIDAR systems capture water elevation and depth at the same time, resulting in an aerial LIDAR study of the land-water interface. Since then, LIDAR technology has considerably expanded its capacity and LIDAR systems are used to perform a series of measurements including cloud profiling, measuring winds, studying aerosols and quantifying various atmospheric components. For example, LIDAR altimeters look downward, atmospheric LIDAR look up, and LIDAR-based collision avoidance systems look sideways.
The reflection on the ground of an airborne LIDAR provides a measure of the reflectivity of the surface (assuming that atmospheric transmittance is well known) at the LIDAR wavelength; however, ground reflection is normally used to measure absorption from the atmosphere. LiDAR systems take advantage of this technology and use LiDAR data to map three-dimensional models and digital elevation.