The main idea of LiDAR (Light Detection and Ranging) technology is based on actively scanning the scene by involving a device which emits electromagnetic radiation in the form of modulated laser light. Generally, such scanning devices illuminate a scene with modulated laser light and analyze the backscattered signal. More specifically, laser light is emitted by the scanning device and transmitted to an object. At the object surface, the laser light is partially reflected and, finally, a certain amount of the laser light reaches the receiver unit of the scanning device. The measurement principle is therefore of great importance as it may be based on different signal properties such as amplitude, frequency, polarization, time, or phase. Many scanning devices are based on measuring the time t between emitting and receiving a laser pulse, i.e., the respective time-of-flight, and exploiting the measured time t in order to derive the distance r between the scanning device and the respective 3D scene point. Alternatively, a range measurement r may be derived from phase information by exploiting the phase difference Δφ between emitted and received signal. According to seminal work, respective scanning devices may be categorized with respect to laser type, modulation technique, measurement principle, detection technique, or configuration between emitting and receiving component of the device. In order to get from single 3D scene points to the geometry of object surfaces, respective scanning devices are typically mounted on a platform which, in turn, allows a sequential scanning of the scene by successively measuring distances for discrete 3D points. LiDAR technology is used for a diversity of applications such as autonomous driving, forestry, biomass estimation, precision farming, archaeology, city mapping, terrain modelling, and metrology.
Explain and discuss the LiDAR technology
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