The full from of Airborne LiDAR is Airborne Light Detection and Ranging. Airborne LiDAR measures the properties of the scattered light to find out information of the distant objects or features. Airborne LiDAR is an optical remote sensing technology. The informations of the objects are calculated from the time interval of the LiDAR pulses. The time delay between the transmitted pulses and detection of the reflected signals are taken as a distance of an object or surface.
Airborne LiDAR systems are include three different technologies such as :
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The three different technologies are working together and represent collected data with the same time stamp. It is very essential that the components or the data must be very accurate timing. The technologies are present over 15 years. Because of the small size it is very useful to use in an aircraft or helicopter. With the help of the Global Positioning System (GPS) we can now accurately determine the position of the aircraft. Sometimes it is very necessary to link GPS satellite systems with GPS ground stations. It is useful to ensure that the aircraft record the same satellite signal as the ground station.
Types of Airborne LiDAR:
Mainly two types of airborne lidar systems are present-
- Airborne Lidar Bathymetry: Airborne LiDAR bathymetry is used to measuring the depths of moderately clear, near-shore coastal waters and lakes from a low altitude aircraft using laser beam. An aircraft flying across and along the coast, scans several swath of the earth surface acquiring an estimate of ground elevation every few square meters.
- Airborne Lidar Topography: Airborne LiDAR topography can be used to collect elevation data through elevation model, conventional ground surveys, photogrammetry and from remote sensing. Airborne lidar topography is an active sensing system which uses light and laser light to measure distance. For accurately measuring the distance, Airborne LiDAR topography system uses global positioning system(GPS) technology. The technology is capable to collect elevation data with an accuracy of 15 cm.
- Airborne LiDAR Hydrography: With the help of Airborne LiDAR hydrography technology we are able to use scanning technology to survey coastal wasters, seabed depths and topographic features accurately. The time interval between two successive reflected pulses at different wavelengths are taken as a water depth. One pulses travel through the air water to the water bottom while another one is reflected from the water surface.
Capabilities and limitations of LiDAR:
- Capabilities: LiDAR technologies are capable to collect topographic and elevation data. But it has to be connected with the ground control station for comparing the pulses. According to the flying height, swath width, scan angle and pulse rate scanning spots are varies.
- Limitations: Airborne LiDAR technologies are not able to collect data in bad weather like rain, fog, moist, smoke and snowstorms. It is only capable to collect data in good and clear weather. In the dense vegetation area Airborne LiDAR is not able to collect signals and the pulses are represented are small and densely spaced.
Airborne LiDAR technology has application in geology, engineering geology, seismology, remote sensing and atmospheric physics.
Digital Photogrammetry